Chapter 92: Phalanges and the Metacarpophalangeal and Metatarsophalangeal Joints

Anatomy of the Middle Phalanx

Compact Bone

Articulates with the distal phalanx through a high-motion joint and proximally with the proximal phalanx through a relatively low motion joint

Enclosed distally within the confines of the hoof and coronary band but it is more exposed proximally, particularly over the palmar and plantar eminences

Palmaro-/plantaroproximal aspect of the middle phalanx is stabilized by the palmar/plantar scutum which represents the combined insertion of the straight sesamoidean ligament and superficial digital flexor tendon and by the axial and abaxial palmar/plantar ligaments of the PIPJ

Additional perimeter support to the distal aspect of the middle phalanx is derived from the surrounding hoof capsule

How is the middle phalanx loaded predominantly?

Loaded predominantly in axial and torsional planes during athletic activity

Ligaments and Tendons Bounding the Middle Phalanx

Common (or long) digital extensor tendons dorsally and the digital flexor tendons palmarly (or plantarly) contribute to motion of the proximal and distal interphalangeal joints and provide resistance to overextension of the distal limb

Middle phalanx is stabilized by strong lateral and medial collateral ligaments of the proximal and distal interphalangeal joints and the suspensory ligament of the distal sesamoid bone

Etiology of Fractures of the Middle Phalanx

• Most common in Quarter Horses and Arabians

• Horses that turn predominantly on their hindlimbs, such as cutting and reining horses, incur comminuted fractures of the middle phalanx almost exclusively in the hindlimbs

  • More than 70% of middle phalanx fractures in one report involved the hindlimb

• Distraction fractures of the plantar eminences occur primarily in the hindlimbs because of the forces incurred during sudden stops and turns, most likely as an avulsion of the bony insertion of the SDFT

• Comminuted fractures of the middle phalanx result from a mixture of axial compression and torsion, common in abrupt sliding hindlimb action

Middle Phalanx Fracture - Clinical Signs

• Lameness is acute and severe

• Comminuted fractures generally result in non-weight bearing lameness and attempts to bear weight often result in hyperextension of the digits and sinking of the MCP/MTP joint

Middle Phalanx Fracture Configurations

Classified as simple or comminuted and fall into one of four categories:

• Dorsal or palmar/plantar intraarticular osteochondral chip fractures

• Palmar or plantar eminence fractures

• Axial Fractures

• Comminuted Fractures

Middle Phalanx - Dorsal or Palmar/Plantar Intraarticular Osteochondral Chip Fractures

• Rare

• Most osteochondral fractures occur on the palmar or plantar aspect of the middle phalanx either immediately lateral or medial to the axial midline

• More prevalent in Quarter Horses and Thoroughbreds

• Do not involve the insertion of the SDFT or distal sesamoidean ligaments and therefore do not distract

• Do tend to grow in situ which increases the likelihood of lameness

• Development of OA is relatively slow

• Surgical removal indicated if lameness examination confirms the midphalangeal region as the site of pain

• Can be incidental findings

Middle Phalanx - Surgical Removal of Palmar or Plantar Fragments

• Surgical removal of palmar or plantar fragments using arthroscopy is recommended

  • Arthroscopic portal made into the proximal aspect of the voluminous palmar pouch of the PIPJ

  • Access for instruments provided by a portal on the contralateral side of the palmar region of the pastern and a second instrument portal can be made ipsilateral and distal to the arthroscope entry for removing large palmar fragments

  • Fragments located more abaxial to the midline are obscured by the middle scutum and may need removal by open approaches

Middle Phalanx - Surgical Removal of Dorsal Fragments

• Dorsal fragments can be removed arthroscopically with an approach over the dorsal joint pouch

  • Most fragments develop lateral or medial to the midline and tend to be small and in close proximity to the dorsal rim of the middle phalanx

  • Limited maneuverability due to attachment of extensor tendon immediately distal to the joint

  • Arthroscope entry usually abaxial to the extensor tendon

  • Instrument access adjacent to the fragment

Middle Phalanx - Prognosis for Dorsal or Palmar/Plantar Intraarticular Osteochondral Chip Fractures

• Prognosis after surgical removal is favorable unless the fragmentation is associated with early joint degeneration

Middle Phalanx - Palmar or Plantar Eminence Fractures

• Can be uniaxial or biaxial

• Result from hyperextension of the pastern joint with tension on the palmar or plantar attachments of the SDF tendon or the palmar/plantar middle scutum and distal sesamoidean ligaments

• Uniaxial fracture does not result in pastern subluxation or the considerable lameness associated with biaxial fracture

Middle Phalanx - Uniaxial Fractures of the Palmar and Plantar Eminences

• Can be treated with selective screw fixation or pastern arthrodesis

• Screw fixation in lag fashion can be performed through stab incisions over the proximal extremity of the fractured eminence with a 4.5 mm screw inserted under radiographic control

  • Interfragmentary screw is inserted in a distal axial direction with the primary access to the eminence gained by splitting the insertion of the SDFT longitudinally

• Delay in presentation or presence of biaxial palmar eminence fractures necessitates pastern arthrodesis and sometimes even with stable articulations and uniaxial eminence fracture arthrodesis can be preferable

• Postoperative cast for 10 days to 2 weeks

• Prognosis after arthrodesis is fair to favorable

• Outlook for return to active work is improved with fractures of hindlimb versus forelimb eminences

• Recuperative periods of up to 12 months are required

Middle Phalanx - Biaxial Fractures of the Palmar or Plantar Eminences

• Result in considerable lameness and instability of the PIP joint which results in considerable hyperextension of the joint with complete loss of palmar/plantar support

• Pastern arthrodesis preferred

  • Plate configurations include a single broad LCP with additional independent lag screws or two narrow DCPs or LCPs placed on the dorsal aspect off the proximal and middle phalanges

  • If two plates are being used, the palmar or plantar eminence fractures are stabilized by screws placed through the distal plate holes which will require additional bending of an LCP if a locking head screw is used in the distal combi hole

    • Alternatively, a cortex screw can be placed in the distal combi-hole to achieve a lag effected to the fractured palmar/plantar eminences

  • If space is available in larger fragments, individual interfragmentary screws unassociated with the plate should be added to strengthen the repair

  • Pastern arthrodesis by plate fixation without an attempt at perfect reduction of the individual eminence fractures is satisfactory, however, callus production and induced secondary lameness are minimized if the eminence fragments can be incorporated into the repair

• Prognosis after biaxial eminence fracture repair by arthrodesis is fair, particularly for fractures involving the hindlimbs

Middle Phalanx - Axial Fractures

• Rare

• Can be repaired with cortex screws applied in lag fashion

• Cast fixation during initial 4 post-op weeks is important

• Prognosis for soundness is guarded because some proliferative new bone formation, especially at the articular margins, is expected as a result of the initial trauma

Middle Phalanx - Comminuted Fractures

• Most common configuration in the middle phalanx

• Severe non-weight bearing lameness with palpable instability and occasionally crepitus of the distal limb

• Treatment options include screw fixation in lag fashion of minimally comminuted fractures, application of a single broad LCP or DCP with additional screws, use of two narrow LCPs or DCPs for fracture fixation and pastern arthrodesis, or application or strategic cortex screws placed in lag fashion in combination with a transfixation cast

• Aim of surgical repair is reconstruction of the distal and to some extent the proximal articular surfaces of the middle phalanx

• If reconstruction of the DIPJ is inadequate or the bone is severely comminuted and unlikely to be adequately repaired with a plate and screws, humane euthanasia should be considered

• Most frequent configuration of comminuted fractures involves fractures in both a sagittal and frontal (transverse) plane often with added comminution on the palmar or plantar proximal aspect

• Marked instability because of connection of the attachments of the palmar or plantar ligaments and tendinous structures is common

• Use of LCPs for comminuted fractures tends to limit screw insertion angle when using a locking screw in the distal plate hole and DCPs are often preferred, but an LCP can be used with cortex screws only where it will act as a LC-DCP

Surgical Repair of Comminuted Fractures of the Middle Phalanx

• I shaped skin incision followed by an inverted Y tendon incision is used to expose the proximal and middle phalanx

• Application of two narrow LCPs or DCPs allows greater versatility in screw placement than a single plate

  • The distal most hole in the plates can be positioned over the abaxial dorsal region of the middle phalanx, leaving the next most proximal plate hole available for cortex screw insertion across the joint in lag fashion

  • Proximal articular surface of the middle phalanx is exposed by severing the collateral ligaments to allow initial reduction and stabilization of the palmar or plantar portions of the fracture to the dorsal struts of bone

  • Sagittal fractures are reduced later with individual screws inserted in lag fashion

  • Cartilage of the PIPJ is removed, distal most screw in either plate inserted initially to engage the palmar/plantar fractured eminences and the plate screws in the proximal phalanx are then inserted

    • If possible, one or two plate screws should be placed transarticularly

  • Postoperative cast fixation for 4-8 weeks

  • Follow-up radiographs at cast removal dictate the period of stall confinement, which is generally an additional 6-12 weeks

  • Postfixation callus development can be extensive, depending on the extent of fracture line reduction and rigidity of the stabilization

  • Most common cause of persisting lameness is OA of the DIPJ

• Repair of severely comminuted fractures with cast or transfixation cast techniques is reserved for fractures that cannot be adequately reduced and stabilized by implants and when humane euthanasia is not an option for the owner

• Complete resolution of lameness with implant fixation can occur, however residual lameness is anticipated if there is inadequate reduction of the fracture fragments entering the DIPJ

• Concurrent fractures of the distal sesamoid bone reduce the prognosis further

Proximal Interphalangeal Joint - Osteoarthritis

• Particularly in breeds with tendency for short upright pastern conformation

• Horses that make quick stops and hard turns with rapid twisting such as Western performance horses and show jumpers

• Treatment of true intraarticular PIP OA is usually surgical fusion of the involved joint

• Response to intraarticular medication with corticosteroid preparations is usually short term

• Most horses continue to form periarticular callus for 6 months after surgical arthrodesis

• Unstable repairs result in exuberant callus which can interfere with the action of the flexor tendons on the palmar or plantar surface of the pastern and occasionally with the extensor tendons over the dorsal middle phalanx region

• Digital extensor tendons can adhere to exostoses on the dorsal aspect of the middle phalanx, pulling on the insertion to the extensor process of the distal phalanx, resulting in residual lameness

• Excessively long screws that penetrate the palmar or plantar surface of the middle phalanx and interfere with the action of the distal sesamoid bone are also causes of residual lameness

Prognosis for PIPJ After Surgical Arthrodesis

• Prognosis after surgical arthrodesis is fair to favorable, particularly for conditions involving the hindlimb

  • Outcome in one report indicated 16/22 horses returned to full function (Schneider, Carnine, and Guffy 1978)

  • Second study indicated 76% of clinical cases became sound after arthrodesis with a better response in the hindlimbs (Martin et al, 1984)

  • Recent study reported a fair outcome after arthrodesis of the PIP joint in Warmbloods or Thoroughbreds with 57% becoming sound and a slightly better outcome for Quarter Horses with 63% returning to athletic function (Herthel et al, 2016)

    • Horses undergoing hindlimb arthrodesis had a better return to function with 73% of horses becoming sound compared to 25% of horses returning to competition after forelimb arthrodesis

  • Superior forelimb outcome data following PIP arthrodesis using a combination DCP-transarticular screw technique was reported where 87% horses returned to their intended use, including 81% of forelimb arthrodeses and 20 of 21 hindlimb arthrodeses (Knox and Watkins, 2006)

PIPJ - SCLs

• SCLs are diagnosed more often than dissecting cartilage flap lesions and involve the distal articular surface of the proximal phalanx or rarely the proximal articular surface of the middle phalanx

• Solitary SCLs are readily apparent on radiographs and some can be clinically silent whereas multiple SCLs are associated with a persistent lameness leading eventually to osteoarthritis

• Intraarticular hyaluronan injections provide temporary pain relief in solitary SCLs

• Surgical curettage of solitary SCLs of the proximal phalanx has been performed

  • Because the lesion is often not approachable arthroscopically, transosseous drilling is used

    • Initially, a small drill bit is advanced under fluoroscopic control into the cyst which is confirmed by drainage of saline previously injected into the PIPJ

    • Drill hole is enlarged with a 5.5 mm drill bit allowing access with a curette to evacuate the cyst

    • Cyst and drill hole can be filled with tricalcium phosphate granules

  • Long term follow-up revealed that 4/5 treated horses were serviceable and could engage in their intended athletic function

• Use of extraarticular cortex screw insertion across solitary subchondral bone cysts in the distal aspect of the proximal phalanx has also been used to resolve cysts that open to the PIP

  • Packing of the bone cyst prior to cortical screw insertion may be helpful and has included cancellous bone, calcium phosphate containing bone morphogenic protein-2 (BMP-2), and tricalcium phosphate

• Multiple cystic lesions show a poor prognosis to medical treatment, leaving elective arthrodesis of the joint as the only treatment

  • Simultaneous bilateral arthrodesis can be performed in foals, whereas staged fusion is elected in adult horses

PIPJ - Luxation and Subluxation

• Usually treated with arthrodesis

• Subluxation is more common and occurs in either a dorsal and palmar/plantar direction

• Dorsal subluxation occurs bilaterally in the hindlimbs of some horses with upright conformation

  • Can be managed with antiinflammatory medication and a controlled exercise program

  • As the horse gains condition, the subluxations often resolve

• Pastern arthrodesis is used to treat recalcitrant dorsal and palmar/plantar subluxations

  • Realignment of severe chronic dorsal subluxations during arthrodesis often requires significant debridement of the osseous and soft tissue structures of the dorsal and abaxial regions of the PIPJ

• Some acquired dorsal subluxations are caused by excessive tension in the DDFT and successful resolution in three hindlimb cases resulted from release of the medial head of the DDFT

• Prognosis after repair of subluxations is fair to favorable

What causes dorsal subluxation of the PIPJ?

• Dorsal subluxation is the result of damage to the suspensory ligament and its terminal extensor branches, occasionally caused by contracture of the distal sesamoidean ligaments

What causes palmar/plantar subluxation of the PIPJ?

• Palmar/plantar subluxation results from failure of the palmar/plantar supporting connective tissues such as the distal sesamoidean ligaments, the middle scutum, and the SDFT insertions

  • Manifest by marked hyperextension of the PIPJ and considerable swelling associated with the soft tissue disruption

PIPJ Luxation and Subluxation - Clinical Signs

• Acute lameness initially with the dorsal subluxations resulting in an obvious dorsal swelling over the PIPJ

• Palmar/plantar subluxation results in hyperextension of the pastern and sinking of the MCP/MTP joint

• Lameness associated with PIPJ subluxation is less severe than that associated with fracture disruption

Arthroscopy of the PIPJ

• Distending the joint before insertion of the blunt obturator-cannula unit is mandatory

• Using both dorsal and palmar/plantar approaches, 62.4% of the joint perimeter can be visualized arthroscopically

  • The abaxial parts of the joint perimeter cannot be visualized

Arthroscopy of the Dorsal Pouch of the PIPJ

• Dorsal (preferred) or lateral

• Arthroscope portal located at the abaxial margin of the common/long digital extensor tendon and at the junction between the proximal and middle third of the outpouching

Arthroscopy of the Palmar/Plantar Pouch of the PIPJ

• Preferably in dorsal recumbency with the distal joints in partial flexion

• Arthroscope portal located in the proximal part of the palmar/plantar outpouching close to the palmar/plantar margin of the proximal phalanx

• Blunt obturator-cannula unit is introduced in a distoaxial direction

Fractures of the Proximal Phalanx - Clinical Signs and Diagnosis

• Comminuted fractures of the proximal phalanx result in severe lameness

• Stable sagittal or intraarticular dorsal and palmar/plantar fractures improve rapidly to mild or moderate weight-bearing lameness

Proximal Phalanx Fracture Configurations

• Two categories

  • Proximal intraarticular osteochondral fractures

  • Fractures involving the shaft or diaphyseal region of the proximal phalanx

Proximal Phalanx Fractures - Etiology

• Cause of most of these fractures is trauma, with hyperextension being particularly important for osteochondral fractures and torsion with axial weight bearing being more important for fractures of the shaft of the proximal phalanx

Proximal Phalanx - Proximodorsal Osteochondral Fractures

• Osteochondral fractures of the proximal dorsal margin of the proximal phalanx within the MCP joint are common in racehorses and also frequently occur in nonracing breeds

• Arise from hyperextension of the MCPJ with impact of the proximal and dorsal aspect of the proximal phalanx onto the dorsal region of MCIII

  • Preexisting subchondral bone disease likely predisposes this region to osteochondral chip fracture

• Initial clinical symptoms include several days of moderate lameness associated with obvious synovial effusion and pain on flexion of the affected joint

  • Depending on the size of the fragment, lameness dissipates quickly

• Most prevalent site is dorsomedial eminence of the proximal phalanx

  • Occasionally both lateral and medial eminences are involved

Proximal Phalanx - Proximal Osteochondral Fractures - Treatment

• Treatment of choice is surgical removal using arthroscopy

  • Small chip fractures (<2 mm in diameter) can be rapidly covered by synovial tissues and many heal without causing clinical symptoms

  • Moderate to large dorsal fragments should be removed to prevent synovitis, cartilage degeneration, and chronic proliferative (villonodular) synovitis mass development

  • Large chip fractures result in erosion of the opposing metacarpal condyle and often result in persistent lameness

  • Arthroscope placed into the joint just proximal to the middle of the visibly distended dorsal joint pouch, adjacent to the extensor tendon because this facilitates examination of both lateral and medial portions of the joint without damage to the dorsal aspect of the sagittal ridge

  • Second entry portal made for fragment removal

  • 6-12 weeks of rest from training, depending on damage to MCIII cartilage

Proximal Phalanx - Proximal Osteochondral Fractures - Prognosis

• Return-to-use rate of 86% for racehorses (Markel, Martin, and Richardson, 1985) and 68% of horses returned at the same or higher level of racing performance

• 75% of horses with other MCP lesions, including arthritis, were able to return to previous use

• Other studies indicate similar excellent results after chip fracture removal with 89% of Thoroughbreds returning to racing and 82% racing at a similar or better class

Proximal Phalanx - Type I Proximopalmar and Proximoplantar Osteochondral Fractures

• Avulsed from the axial, proximal, plantar or palmar rim of the proximal phalanx and are mostly articular

  • Most have extensive regions of short sesamoidean ligament insertion still attached to the avulsed fragment

  • Lameness minimal and usually only evident at higher speeds

Proximal Phalanx - Type II Proximopalmar and Proximoplantar Osteochondral Fractures

• Type II fractures - larger, abaxially located, partly articular osteochondral fragments

  • Extend distad 2 to 3 cm and contain minimal articular cartilage

  • Do not appear to produce persistent lameness

Proximal Phalanx - Proximopalmar and Proximoplantar Osteochondral Fractures

• Affected MTP/MCPJ often exhibit synovial effusion, mild pain on flexion, and a mild to moderate response to flexion tests

• Less common in the forelimb, possibly as a result of a more angled shape to the equine palmar aspect of the proximal phalanx compared with the plantar

• Most prevalent in Standardbreds

  • 11.8% of all Standardbred yearlings in Norway and 28.8% of yearlings in Sweden were affected

• In Warmbloods they are often overlooked until they are diagnosed in 3-6 year olds when training level for show jumping is increased

• Routine oblique radiographic views are not satisfactory for delineating Type I fractures

  • Better projection results from raising the radiographic beam to 20-30 degrees above horizontal and taking the oblique projections only 15-20 degrees dorsal to a standard lateral

  • Highlights the plantar rim of the phalanx and the associated base of the proximal sesamoid bone

  • Allow differentiation of Type I axial fractures from Type II abaxial fractures (nonunited proximal plantar tuberosity of the proximal phalanx)

Proximal Phalanx - Type I Proximopalmar and Proximoplantar Osteochondral Fractures - Treatment

• Type I plantar fracture fragments often removed in yearlings to prevent development of lameness during training and racing

  • Arthroscopic approach through the plantar pouch of MTPJ

    • Instrument portal prepared at base of proximal sesamoid bone, exact location identified with a needle

    • Fragments dissected from the covering of synovial membrane and remnants of the attached short sesamoidean ligaments and removed

    • Use of motorized resectors, radiofrequency cutting loupes, or diode or CO2 laser for removing excessive soft tissue proliferations and resection of the fragment reduces intraoperative bleeding and improves visualization

    • 6-12 weeks of rest from training depending on damage to the distal sesamoidean ligaments at the time of surgery

    • In a review, 63% of horses returned to racing at or above their preoperative level (Fortier, Foerner, and Nixon, 1995)

      • Abnormal arthroscopic findings, including articular cartilage loss over the palmar condyles and extensive synovial proliferation, had a negative impact on successful outcome

Proximal Phalanx - Type II Proximopalmar and Proximoplantar Osteochondral Fractures - Treatment

• Surgery is rarely indicated for Type II abaxial osteochondral fractures

  • Incidence of these fragments is lower (2.4% of Standardbred yearlings) and they might not be fractures but rather a form of delayed ossification

  • Lesions in 11/18 horses had radiographically united to the parent proximal phalanx after 12 months

  • Occasionally, nonhealing abaxial "fractures" and true traumatic fractures with fresh margins and associated lameness require screw fixation inserted in lag fashion

    • Only warranted when lameness is present

Dorsal Frontal Fractures of the Proximal Phalanx

• Relatively rare

  • Represented 7% of fractures involving the shaft of the proximal phalanx

• Predominantly in Thoroughbreds

• More prevalent in the hindlimbs

• In a review of 22 short dorsal frontal plane fractures in Thoroughbreds, 17 involved the hindlimb (Wright and Minshall, 2018)

  • 20/22 involved the dorsomedial aspect of the proximal phalanx which contradicts previous literature which supported a dorsolateral preponderance

• Tend to be short, extending from the articular surface 2-5 cm distad in the dorsolateral cortex of the proximal phalanx

• Generally complete and minimally displaced

Dorsal Frontal Fractures of the Proximal Phalanx - Treatment

• Complete fractures are better repaired using screw fixation in lag fashion, although nondisplaced fractures heal with conservative therapy

  • Complete displaced fractures should be repaired with interfragmentary screws

  • Surgical repair can be supplemented by arthroscopic examination of the dorsal intraarticular region of the affected joint and debridement of associated cartilage damage

  • Insertion of one or two 3.5 mm cortex screws using lag technique under arthroscopic guidance is recommended

  • Recover in a soft bandage

  • Two weeks of complete stall rest followed by 6 weeks of limited daily handwalking

  • Implants removed only where lysis or reaction has developed beneath screw heads

Dorsal Frontal Fractures of the Proximal Phalanx - Prognosis

• 76% of horses raced after surgical repair using a single lag screw (Wright and Minshall, 2018)

• If conservative therapy is selected, adequate radiographic healing of the fracture occurs in 4-6 months

  • Prognosis for return to racing is favorable with 6-9 horses reported to have returned to satisfactory performance with nonsurgical therapy

Proximal Phalanx - Diaphyseal Fractures

• Most axial fractures of the proximal phalanx occur in the sagittal plan and propagate distad from the articular surface of the MCP/MTP joint

• Midsagittal groove is mechanically predisposed to the initiation of the fracture, possibly as a result of torsion applied to the sagittal groove from the opposing articular surface of the sagittal ridge of MCIII or MTIII

• More common in the forelimbs and are particularly prevalent in racehorses

• Subchondral bone trauma and the development of short fractures extending from the sagittal groove of P1 are well characterized in non-racehorses, particularly Warmbloods

  • Considered stress fractures, have significant variation in configuration, and are often accompanied by OA with a poor prognosis

  • In a recent study of 19 horses, 18 were treated conservatively and 13 had persisting lesions and lameness (Gold, Werpy, and Gutierrez-Nibeyro, 2017)

• Clinical signs depend on extent of fractur propagation

  • Incomplete sagittal fractures show moderate pain of relatively short duration

  • Fractures extending the full length of the proximal phalanx and those that tend to comminute result in non-weight bearing lameness and moderate swelling of the pastern

• Most fractures commence in the sagittal grove and extend distad

• Complete fractures exit on either the lateral or rarely medial cortex of the proximal phalanx or enter the proximal interphalangeal joint

• A study in a Warmblood-dominated population revealed that short sagittal fractures are often not bicortical and are located significantly more dorsally in the forelimbs compared to the hindlimbs (Brunisholz et al, 2015)

Proximal Phalanx Short Sagittal Fracture Treatment

• Many short sagittal fractures are initially treated conservatively because  the fracture is incomplete and stable

• Screw fixation with lag technique is often reserved for fractures that do not heal after 3 months of conservative therapy, but screw stabilization induces primary bone union and reduces the chance for further propagation of the fracture in the convalsecent period

  • Interfragmentary screw fixation may be considered as the initial treatment, especially in Warmblood horses

  • Racehorses can return to training more quickly and have an excellent prognosis; 11/12 horses repaired with screw fixation in a recent study went on to race (Smith, Corletto, and Wright, 2017)

Proximal Phalanx Complete Nondispalced and Displaced Fracture Treatment

• Complete nondisplaced and displaced fractures require surgical repair

  • Prerequisite for selecting screw reconstruction of proximal phalanx fractures over transfixation casts or external fixator devices is the presence of an intact strut of bone spanning from the MCP to the PIP joint

  • Disruption of weight-bearing support without an intact bony column is generally a contraindication to screw repair alone

  • Occasionally, the articular surface of the MCP/MTP and PIP joints can be reconstructed with interfragmentary screws, but without an intact strut, axial stabilization must be provided with a transfixation device

Short Incomplete Sagittal Fractures of the Proximal Phalanx - Surgical Techniques

• Repaired using cortex screws placed in lag fashion

• A 4.5 mm cortex screw is applied in the proximal aspect of the proximal phalanx immediately distal to the sagittal groove

• An additional more distal cortex screw can be placed 18-20 mm distal to the initial screw depending on fracture length

Long Incomplete and Nondisplaced Complete Sagittal Fractures of the Proximal Phalanx - Surgical Techniques

• For routine nondisplaced fractures, the proximal phalanx can be stabilized by inserting screws in lag fashion through stab incisions

• Some incomplete sagittal fractures can be repaired standing

• Most proximal screw in the series preferably should be a 5.5 mm cortex screw for additional compression of the articular surface

• Ideally, the proximal screw should pass within 5 mm of the most distal point of the sagittal groove of the proximal phalanx to provide maximum compression to the articular surface

  • This screw should penetrate the trans cortex and the screw head should be adequately countersunk to avoid torque on the screw shaft from the oblique angle of the cortex beneath the head

• Additional screws are placed at intervals of 20-22 mm until the entire fracture line has been stabilized

• Additional compression of the proximal aspect of a long sagittal fracture, particularly those that are complete, may be derived from using two cortical screws in the proximal aspect of the phalanx

  • One screw is inserted in the dorsal proximal portion of the phalanx while the second screw is applied in the palmar/plantar proximal quadrant of the bone

Frontal Plane Fractures of the Proximal Phalanx - Surgical Techniques

• Less common

• Often uniplanar and can be repaired placing screws in a dorsal to palmar/plantar direction

• More comminuted frontal plane fracture configurations can result in trauma to the distal sesamoidean ligaments either by sharp fragments or instruments during repair which can result in subluxation of the proximal interphalangeal joint after fracture healing

Proximal Phalanx Diaphyseal Fractures - Postoperative Care

• Fiberglass cast is fracture is extensive

• Simple fractures repaired with several screws can be recovered in a firm bandage or splint

• Most horses can return to light training 4-6 months after repair

• Proximal phalanx fractures of the hindlimb are more likely to require cast support for the recovery phase because of increased torsional loads on the hindlimbs during recovery

• Outcome after screw fixation of long incomplete fractures is fair with 56% of Thoroughbreds in the UK returning to race

• Implant removal is not necessary

Proximal Phalanx - Displaced Complete Sagittal Fractures

• Complete fractures that involve sagittal and oblique fracture planes with mild to moderate displacement can generally be accurately reduced using arthroscopic visualization of the dorsal aspects of the fracture in the MCP/MTP joint

• For more complex or displaced fractures, open approach to the proximal phalanx may assist in reduction and stabilization of fracture planes remote to the fetlock

• Access for fracture debridement and reduction is provided by arthroscopic examination in the dorsal joint pouch or an incision over the dorsal aspect of the sagittal fracture

  • Incision for open approaches usually enters the MCP or MTP joint for direct inspection of articular surface

• More complicated fractures require a more extensive longitudinal incision and occasionally an "I" incision or curvilinear flap

• Separate stab incisions can be used for placing the screws in lag fashion in a lateral plane to stabilize the sagittal fracture and reduce the extent of soft tissue dissection

• Extensive fractures that involve multiple sagittal and front planes require an extensive open approach using either an I-shaped incision that exposes the entire dorsal and abaxial cortices of the proximal phalanx or an S-shaped incision

  • S-shaped incision involves severing a collateral ligament of the MCP or MTP joint to expose the proximal articular surface of the proximal phalanx

• Most screws placed in lateromedial or dorsopalmar/plantar direction

• Using an I shaped incision preserves the collateral ligament and metacarpo/metatarsosesamoidean ligaments and provides some opportunity for a return to competition

• Limb is cast to the proximal aspect of MCIII or MTII for 3-6 weeks

• Radiographic evaluation used to determine appropriate cast time

Proximal Phalanx - Severely Fragmented (Comminuted) Fractures

• Fractures without an intact strut of bone are poor candidates for internal fixation

• Lameness is marked and considerable swelling can develop if the limb is left unbandaged for any length of time

• Extensively fragmented fractures should be stabilized with a cast before transfer of the horse for evaluation and surgery

• Transfixation casts usually provide a reasonable possibility of salvaging the horse, return to athletic activity is rarely possible

• Transfixation techniques limit the collapse of the fracture within the cast by using transcortical pins in the distal and midportion of MCIII or MTIII

• Alternative to a transfixation cast is the external skeletal fixation device

  • Healing of a severely comminuted fracture was achieved in 8/13 horses using an external skeletal fixation device

• Most significant complications of transfixation casts and the external skeletal fixator is ring sequestrum formation around the pin tracts and subsequent fracture through a pin hole

Palmar/Plantar Metacarpal/Metatarsal Fragmentation

• Trauma induced disorder that results from the accumulated stress and sclerosis that develops during racing, also been referred to as palmar osteochondral disease (POD)

• Mostly Thoroughbred racehorses that are 3 years old or older and have moderate to severe MCP/MTP lameness

• Identified on standard lateral and flexed lateral projections

• Flexed DP provides detail of the palmar/plantar surface without overlap of the proximal sesamoid bones

• Radiographic lesions appear as focal radiolucencies in the palmar condyles, disruption of the outline of the subchondral bone, including crescent, flattened, and concave lesions, and focal sclerosis in the palmar/plantar region of the condyles

• Medial condyle is generally more severely affected than the lateral condyle in the forelimb while the lateral condyle is predominantly affected in the hindlimb

• Secondary arthritic changes are common - periarticular osteophytes or enthesophytes, narrowing of the joint space, and supracondylar lysis

• Prominent secondary feature is intense sclerosis of the palmar/plantar region of the condyle, deep to the lytic region

• Morphologic assessment indicates an area of acellular and apparently necrotic bone over the entire distal palmar region of the affected metacarpus

  • Deep to the necrotic area is a zone of new bone formation producing a sclerotic barrier that compensates for the biomechanical dysfunction of the palmar fracture

• Remodeling and fracture changes are a result of accumulated stress fractures in the palmar/plantar region of the condyle, largely as a result of hyperextension of the MCP/MTP joint

• Early recognition helpful because sclerosis can be reduced or allowed to remodel rather than progress to a palmar fracture

  • Rest from active race training for 60-90 days allows most horses to return to racing

• In a study of Thoroughbred racehorses with palmar/plantar osteochondral disease confirmed by scintigraphic and radiographic examination, 95% returned to racing, most at the same or an improved class (Tull and Brammlage, 2011)

• Difficult to treat once bony changes become extensive, efforts at early detection and rest from race training using free choice paddock exercise are important

Apical Sesamoid Bone Fractures

• Common in hindlimbs of Standardbreds

• Prognosis often dictated by extent of loss of suspensory ligament insertion and preexisting suspensory desmitis

• Apical fractures involving the proximal 1/4 to 1/3 of the proximal sesamoid bone always contain an articular component, but do not result in extensive suspensory derangement and lameness diminishes rapidly

Apical Sesamoid Bone Fracture Treatment

• Removal of apical fragments up to 1/3 of the proximodistal dimension of the proximal sesamoid bone is recommended

• Removal of the proximal 1/3 of the proximal sesamoid bone results in delay of return to racing and a considerably reduced likelihood of a successful postinjury career

• Large apical fractures with obliquity to the fracture plane may be better candidates for internal fixation

• Arthroscopic removal of apical fractures results in less-extensive dissection and secondary fibrosis

  • Arthroscope inserted in the proximal aspect of the palmar or plantar pouch and instrument portal is made at the level of the fracture, allowing dissection of the fragment from the suspensory attachment

  • Use of the contralateral palmar/plantar pouch for arthroscope entry often provides better visualization of the apical fracture and an unfettered region for instrument access

Midbody Sesamoid Bone Fractures

• Slightly more prevalent in Thoroughbreds and require internal fixation for adequate fracture union

• Should be repaired with either circumferential cerclage wire or screw fixation using lag technique

• Recent publications suggest screw fixation may be the only option for Thoroughbreds to return to athletic capacity

Midbody Sesamoid Bone Fractures - Screw Fixation in Lag Fashion

• Performed from the base or apex of the bone depending on orientation of fracture plane

• Oblique fracture with fracture plane declining from axial to abaxial best treated with interfragmentary screws placed from the apex, whereas a fracture declining from abaxial to axial is best approached from the base or from a contralateral approach allowing insertion of oblique proximal to distal oriented screws

• For screw insertion from the base, the screw head of the 4.5 mm cortex screw should come to lie between the oblique and straight distal sesamoidean ligaments in a natural fossa in the base of the proximal sesamoid bone

• Proximal to distal oriented screws are inserted proximolaterally at the apex of the bone, embedded in the insertion of the lateral suspensory branch

• A single 4.5 mm cortex screw or two 3.5 mm screws used

• Returns up to 60% of Thoroughbred horses to active racing

• Circumferential wiring has largely been reserved for Standardbreds

Basal Seasamoid Bone Fractures

• Involve the origin of all the distal sesamoidean ligament

• Prognosis unfavorable

• Inverse relationship between dorsopalmar/plantar fragment length and likelihood of return to racing

  • Basal osteochondral fragments that do not extend to the palmar/plantar surface have a much better prognosis with 59% returning to racing

Basal Sesamoid Bone Fracture Treatment

• Two 3.5 mm cortex screws preferred to distribute fracture compression across the thin basal slab

• Many of these fractures can be removed arthroscopically

  • In a study, 57% of horses with fragments involving less than 25% of the base successfully returned to racing after fragment removal, compared to 40% with fragments involving more than 25% but not the entire base (Southwood and McIlwraith, 2002)

Abaxial Sesamoid Bone Fractures

• Must be assessed by a 60 degree skyline projection of the abaxial surface of the proximal sesamoid to demonstrate whether the abaxial fracture enters the joint or is located palmarly/plantarly and is extraarticular

• Intraarticular fragments can be removed under arthroscopic visualization, whereas nonarticular fractures are best treated conservatively

• Arthroscopic access using a contralateral palmar/plantar pouch entry is recommended for abaxial fracture removal

• Return to function is fair to good (61%) depending on the length of the intraarticular fracture

Sagittal Sesamoid Bone Fractures

• Rare

• Tend to occur on the axial margin in conjunction with other MCP/MTP injuries such as condylar fractures

• Occasionally can be repaired using the tips of several 3.5 mm cortex screws placed in lag fashion in a lateral to medial orientation

• Application of a cast for 2-3 weeks

  • If things healing well at that point can be changed to a cast bandage or heavy support bandage

• Because they usually occur in conjunction with displaced lateral condylar fractures, return to athletic activities is unlikely

• Occasionally MCP/MTP arthrodesis is necessary

Biaxial Sesamoid Bone Fractures

• In most cases, requires MCP arthrodesis for return to comfortable weigh bearing

Axial Osteitis of the Proximal Sesamoid Bones

• Axial lysis, occasionally with fragmentation has been described in proximal sesamoid bones associated with injury or avulsion of the intersesamoidean ligaments

• Most frequent in Warmbloods, especially Friesians

• Hindlimb predominantly affected

• Lameness often commences acutely and can be severe, chronic lameness then develops

• Debridement returned 2/9 horses to riding in one study (Brommer et al, 2014)

• Better results have been achieved with arthroscopic surgical debridement and stem cell grafting or ultrasonographically guided stem cell injection adjacent and parallel to the palmar/plantar aspect of the contralateral sesamoid bone

MCPJ/MTPJ - Chronic Proliferative (Villonodular) Synovitis

• Most frequent cause is proximodorsal osteochondral fractures of the proximal phalanx that are not immediately treated

• Also commonly develop with advancing OA changes within the joint

• Horses with long pasterns predisposed

• Visible and palpable mass evident at the proximal dorsal aspect of the affected MCP region

• Lameness usually Grade II to III

• Radiographs occasionally show cortical lysis on the dorsal region of MCIII under the enlarging mass

• Involvement of the hindlimbs is rare

• Definitive diagnosis requires arthrography or ultrasound

• Most masses are 7-10 mm in diameter

• The minimum thickness that warrants surgery is 4 mm, smaller masses can be treated with intraarticular atropine and steroids

• Enlarged medial portion of the chronic proliferative plica is usually thicker than the lateral portion

• Critical factor for decision for surgery is the extent of OA present

MCPJ/MTPJ Fibrous Masses Secondary to Osteochondral Fragments and Other Fracture Diseases

• Osteochondral fragments and other fracture diseases in the MCPJ result in secondary fibrous mass development and these fibrous masses can be removed without difficulty and with reasonably favorable prognoses

MCPJ/MTPJ Fibrous Masses Secondary to OA

• Masses secondary to OA are generally larger and more chronic, associated arthritis dictates likelihood of return to work once mass is removed

MCPJ/MTPJ Primary Chronic Proliferative Masses

• Primary chronic proliferative masses can develop without an obvious initiating factor and most likely result from hyperextension of the MCPJ and impact trauma on the normal synovial plica

  • Hemorrhage and fibrosis in the plica results in significant enlargement which is then more easily and repeatedly injured during exercise

  • Horses do well after surgery to remove the mass

MCPJ/MTPJ Arthroscopic Approaches to Remove Chronic Proliferative Masses

• Arthroscope portal made in dorsolateral aspect of the dorsal pouch of the MCP/MTPJ at the middle of the proximodistal dimension of the pouch

• Instrument portal made in similar region on the dorsomedial aspect

• Most chronic proliferative masses involve both lateral and medial portions of the plica and exchange of the arthroscope and instrument portals is required for adequate removal

• Mass removal using synovectomy instruments, guarded scalpels, radiofrequency cutting probes, or biopsy suction punch rongeur for smaller masses

MCPJ/MTPJ - Chronic Proliferative (Villonodular) Synovitis Post-operative Therapy

• Intraarticular injections of 20-40 mg of hyaluronan

• Repeat doses in 3-4 weeks to minimize capsule tiedown to the dorsal aspect of the third metacarpus/metatarsus

• Return to race training depends on concurrent arthritis

MCPJ/MTPJ Osteoarthritis

• Respond poorly to intraarticular medication and require frequent injections to remain comfortable

• Collapse of the medial compartment of the MCPJ is more prevalent than lateral and often indicates the likelihood of a career ending lameness

• Therapeutic options limited

  • Pain relief from intraarticular steroids but continued cartilage degradation is inevitable

  • Injection or surgical implantation of MSCs may provide generalized improvement in joint function

    • Antiinflammatory, antiapoptotic, and trophic effects at synovial membrane boundary

  • In final stages of joint deterioration, some improvement results from administration of silicone oils or polyacrylamide solution

  • Some need MCP arthrodesis to be comfortable

MCPJ/MTPJ OCD

• OCD can develop as palmar/plantar dissecting flaps on MCIII or MTIII or more frequently in the form of dissecting cartilage flaps that appear as mineralizing lesions on the dorsal sagittal ridge and parasagittal region of MCIII or MTIII

  • Common in young horses 8-24 months old

  • Dorsal OCD lesions often bilateral but can affect all four MCP/MTP joints

• Clinical symptoms - mild swelling and minimal lameness

MCPJ/MTPJ Sagittal Ridge OCD

• Sagittal ridge OCD affecting the most distal portion of MCIII frequent findings on Thoroughbred yearling sales radiographs, particularly on the DP and flexed lateral views

  • Represent incomplete mineralization of the cartilage forming the sagittal ridge

  • If lameness and effusion develop as they start race training surgical debridement may be necessary

    • Returned 11/12 Thoroughbreds to racing

• Dorsal sagittal ridge lesions often manifest as mineralized densities adjacent to the sagittal ridge, often arise from the proximal condylar cartilage and are more correctly termed dorsal parasagittal or dorsal condylar OCD lesions

Palmar/Plantar Metacarpal/Metatarsal OCD

• Palmar/plantar metacarpal/metatarsal OCD lesions which result in debilitating lameness, often progress to OA and represent the most serious form of MCP/MTP OCD

  • Occur in horses as young as 10 months but more common in young racing-age horses

MCPJ/MTPJ SCLs

• SCLs of the distal MCIII or MTIII condyle occur most commonly in weanlings and yearlings but can be first diagnosed in 2 year olds in training

  • Most open to the joint just dorsal to the transverse ridge by a narrow communicating channel

  • Occasionally multiple cysts present in the same bone and can be bilateral

  • Cysts of the proximal articular surface of the proximal phalanx also see often opening in or near the sagittal grove

Degree of Lameness with MCP/MTP OC

• Degree of lameness depends on type of MCP/MTP OC

  • Dorsal sagittal ridge lesions - mild to minimal lameness but flexion tests often positive

  • Other forms of OCD and SCL result in more significant lameness

    • Lameness and pain on flexion most pronounced with palmar OCD lesions in yearlings

Palmar MCIII and Plantar MTIII OCD Treatment

• Palmar MCIII and Plantar MTIII lesions are relatively inaccessible and surgical therapy not possible unless lesion located unusually far caudad on the condyles or sagittal ridge

  • Can sometimes be partially debrided under arthroscopic guidance with a palmar or plantar pouch approach

  • OA with persistent lameness usual sequela

MCPJ/MTPJ Dorsal Sagittal Ridge and Parasagittal Condylar OCD Treatment

• Dorsal sagittal ridge and parasagittal condylar lesions should be surgically removed under arthroscopic guidance

  • Dorsal or lateral recumbency, joint distended

  • Arthroscope portal placed in the proximolateral quadrant of the outpouching with the limb in extension

  • Blunt obturator-cannula unit inserted perpendicular to the skin initially then directed parallel to the articular surface of MCIII

  • For lesions located more distally on the sagittal ridge of MCIII/MTIII arthroscope portal is placed just distal to the center of the outpouching

    • After insertion of the arthroscope, the joint is flexed to visualize the distal part of the sagittal ridge

Treatment of SCLs of MCIII or MTIII with Narrow Openings to the Joint

• Subchondral cystic lesions of MCIII or MTIII that have narrow openings to the joint can be treated successfully with several injections of hyaluronan

  • Most yearlings do well and lameness quickly resolves

  • Cystic cavity generally fills in but may take 1-2 years

  • If lameness persists surgery should be considered

Treatment of SCLs of MCIII or MTIII with Wide Openings to the Joint

• Cystic lesions with wide channels to the articular surface do not respond to conservative therapy well and debridement is often recommended at initial diagnosis

  • Can be accomplished via dorsal arthroscopy with the MCP joint flexed

  • Most cysts can be curetted and bone grafts are not necessary

  • In mature horses, chondrocyte or stem cell grafts have been used to assist in repair of the subchondral architecture and overlying cartilage

  • Application of a cortical screw across the subchondral cyst has been used

  • Arthroscopic techniques can only be used with cysts opening on or dorsal to the transverse ridge of MCIII

    • More palmar cysts rare and best approached transosseously through drilling or for application of a transcystic cortical screw

Treatment of SCLs of Proximal P1

• Cysts of P1 can be debrided with difficulty from the articular surface, particularly in MTP joints where the joint separates with flexion

  • If the cyst is inaccessible using arthroscopy, an extraarticular cortical screw can be inserted across the cyst

Prognosis for OC Lesions of the MCIII and MTPIII

• Outlook for a sustained athletic career is favorable for subchondral cystic lesions of the distal MCIII or MTIII, reasonably favorable for dorsal sagittal ridge and parasagittal OCD, and poor for palmar metacarpal OCD flaps

MCPJ/MTPJ Luxation

• Lateral or medial complete luxation occurs after rupture of either medial or lateral collateral ligament

• Results primarily from entrapment of the distal limb in holes in the ground or cattle grates

• Radiograph with a DIP with the limb under lateral or medial bending stress

MCPJ/MTPJ Collateral Ligaments

• Each collateral ligament of the MCP/MTP joint is composed of:

  • A superficial portion that originates in the epicondylar fossa of MCIII/MTIII and courses distally to the proximal phalanx

  • A deep part that also originates in the epicondylar fossa of MCIII/MTIII but then courses distopalmarly/plantarly to its insertion on the palmar/plantar eminence

MCPJ/MTPJ Luxation Treatment

• Treatment of closed luxations involves cast fixation for 6 weeks

• Surgery for open luxations is necessary for adequate wound debridement and soft tissue closure

  • Treatment of the luxation in a splint is an option for the acute inflammatory phase until the infection is controlled and a cast can be applied later for increased stabilization or arthrodesis can be performed if the joint surface is extensively damaged

MCPJ/MTPJ Luxation Prognosis

• Three case series have been published

  • In one 5 with closed luxation and 5 with open luxation and the majority were sound at follow-up with one being ridden (Yovich et al, 1987)

  • A more recent series concluded prognosis was favorable for return to function after conservative therapy (Tenney and Whitcomb, 2008)

  • Most recent series included 15 horses treated conservatively with cast fixation (Rebsamen et al, 2011)

    • 67% returned to use as pleasure riding horses

    • 13% pasture sound

    • 20% euthanized because of persisting lameness

    • All horses had some OA of the affected fetlock joint and 6/15 developed OA of the PIP

• Prognosis after development of infection is guarded and chronic lameness can be expected

Complex Tenosynovitis

Self-perpetuating cycle of DFTS fibrosis, repeat tearing, and annular ligament thickening caused by untreated tenosynovitis or tenosynovitis associated with more serious diruption of the DFTS, the various mesotenons, and manica flexoria, the annular ligament of the fetlock joint, or the flexor tendons themselves

Tenoscopic Mass Removal

• Entry portal on the palmarolateral or plantarolateral surface immediately distal to the palmar/plantar annular ligament

• Tenosynovial masses resected with motorized synovial resectors or by division at attachments with biopsy-cutting forceps, arthroscopic scissors, or retractable blades and subsequent removal with grasping forceps using an additional instrument portal

Annular Ligament Transection

• Only effective treatment for annular ligament constriction syndrome is division of the ligament

• Tenoscopic examination of the DFTS with an arthroscope entering distal to the annular ligament allows visual inspection of the entire sheath cavity and division of the annular ligament

• Slotted cannula with obturator in place is inserted under direct arthroscopic visualization, ensuring it is external to the manica flexoria

• As the obturator nears the distal portal the arthroscope is removed and the obturator and cannula are exteriorized through the vacant portal

• Unsheathed arthroscope is inserted to view and verify the flexor tendons, sesamoid surface, and annular ligament

• Slot is oriented to open directly toward the annular ligament and the 90 degree angle sharp blade is drawn across the fibers of the annular ligament to sever the full thickness

• Alternatively, once the slotted cannula is placed, freehand division of the annular ligament can be performed without arthroscopic visualization

  • Verification of complete division of the annular ligament fibers is done by palpation of the tip of the 90 degree blade through the skin

• Arthroscopic guided free-hand division of the annular ligament using right-angled blades, hook knives, radio-frequency probes, or bistoury can also be used

Tendon Debridement in the DFTS

• In the forelimb, tears predominantly affect the lateral border of the DDFT, whereas manica tears are the most frequent lesions in the hindlimb

  • One study reported that in the hind limbs of show jumping horses, tears of the DDFT occur more frequently than manica tears (Arensburg et al, 2011)

• Tears in the DDFT can extend 4-10 cm in length and often involve the DDFT from the level of the apex of the proximal sesamoid bones (inside the manica flexoria) and extend distal to the midportion of the proximal phalanx

  • Trimming of exposed tendon fibers can be accomplished using a combination of biopsy suction punch rongeurs, right angled biopsy rongeurs, and motorized resectors

• Short linear tears in the DDFT generally have a good prognosis, however long tears (>4 cm) are more difficult to return to function by debridement

• Most manica tears develop along the medial attachment of the SDFT and the manica recoils laterally

Postoperative Management Following Tenoscopy for Debridement

• Hyaluronan (20-40 mg) can be injected into the tendon sheath at the time of wound closure or later at suture removal

• Injection of tPA for 3 days after surgery, using 500 ug injected daily may also reduce fibrin deposition and adhesion formation

• Limb bandaged for 3-4 weeks after surgery

• Handwalking initiated 5 days after surgery and time period increased rapidly

• If adhesiolysis was performed at surgery, follow-up injections of hyaluronan recommended 2 and 5 weeks post-op

Prognosis for Tenoscopy for Debridement

• Tenoscopic mass removal and annular ligament division revealed cosmetically acceptable results in 22/25 horses

  • Lameness resolved in 72%

• In a larger series having tenoscopy for nonseptic conditions of the DFTS, tears of the manica flexoria were found in 23/76 and most had a favorable outcome (Smith and Wright, 2006)

  • Marginal tears of the DDFT were associated with postoperative lameness and long tears were associated with a reduced performance level when compared with short tears

• A case series on horses that had tenoscopic surgery for nonseptic tenosynovitis of the DFTS associated with longitudinal tendon tears found that only 38%, mainly Warmbloods used for show jumping or dressage, returned to an equal or higher level of work after surgery (Arensburg et al, 2011)