Osteochondral fragmentation of the plantar/palmar proximal aspect of the proximal phalanx in racing horses

SUMMARY The clinical presentation and outcome of treatment is presented for 26 cases of osteochondral fragmentation of the plantar/palmar proximal aspect of the proximal phalanx. Twenty-three were racing Standardbreds and three were racing Thoroughbreds. The most common reason for presentation was an inability to run straight at high speed. Only eight horses presented for lameness, although on examination 19 were lame. A positive flexion test was recorded in 90% of affected fetlock joints and effusion in 48%. Arthroscopic fragment removal was performed on 23 occasions in 21 horses and arthrotomy in one horse. Of the 16 horses that had returned to racing, 12 had improved their performance, while three showed no improvement, and one was retired for other reasons. In three horses refragmentation occurred after surgery, two of which had improved after initial arthroscopic removal. Degenerative changes within the fetlock joint were detected at surgery in eight horses. Of the four horses treated conservatively, one returned to its previous level of performance temporarily after intra-articular medication, one showed no improvement and two were still resting. Plantar/palmar osteochondral fragmentation of the proximal aspect of the first phalanx is a common cause of low-grade lameness in racing horses, and arthroscopic removal results in improvement in race performance in a high percentage of cases.     

SCINTIGRAPHIC ASSESSMENT OF THE METACARPOPHALANGEAL AND METATARSOPHALANGEAL JOINTS OF HORSES WITH JOINT PAIN

Our aims were to evaluate the pattern of radiopharmaceutical uptake in horses with lameness related to the metacarpophalangeal and/or metatarsophalangeal joint and compare the results with similar information from sound horses. It was hypothesized that there would be a difference in radiopharmaceutical uptake between the lame and contralateral limb in unilaterally lame horses and that there would be a difference between lame and sound horses. Nuclear scintigraphic images of 43 horses with forelimb lameness and 30 horses with hindlimb lameness were evaluated. In all horses lameness was improved by intraarticular analgesia of the joint, or by perineural analgesia of the palmar/plantar (at the junction of the proximal 3/4 and the distal 1/4 of the metacarpal/metatarsal regions) and palmar/plantar metacarpal/metatarsal nerves. All images were assessed subjectively and a quantitative image analysis was performed by drawing a vertical line profile through the center of each joint in the lateral images and using region of interest analysis in both lateral and dorsal/plantar images. Ratios of radiopharmaceutical uptake were compared for each region between lame and contralateral limbs in unilaterally lame horses and between lame and control horses. There was a significant difference in the ratio of radiopharmaceutical uptake in the proximal aspect of the proximal phalanx between lame and nonlame forelimbs in unilaterally lame horses and in both lame and contralateral limbs of lame horses compared with control horses for the regions of the distal aspect of the third metacarpal/metatarsal bone and the proximal sesamoid bones. However, the profile analysis was of limited clinical value.     

Arthroscopic Removal of Palmar/Plantar Osteochondral Fragments from the Proximal Interphalangeal Joint in Four Horses

Objective— To describe anatomic considerations and arthroscopic technique in horses for arthroscopic removal of palmar/plantar osteochondral fragments from the proximal interphalangeal (PIP) joint. Study Design— Retrospective study. Animals— Adult horses (n=4) with osteochondral fragments of the palmar/plantar PIP joint. Methods— Arthroscopic removal of palmar/plantar osteochondral fragments within the PIP joint was performed with horses in dorsal recumbency under general anesthesia. Medical records of affected horses were reviewed to determine history; physical, lameness, and radiological findings; surgical technique; complications and outcome. Results— Two horses had lameness localized to the PIP joint. Two other horses had lameness suspected, but not confirmed to the pastern region. One of these horses had a history of intermittent lameness, but was not lame on admission. All horses had radiographic evidence of palmar/plantar osteochondral fragmentation within the PIP joint. Fragmentation was located abaxially in 2 horses in the hind limb and axially in 2 horses in the left forelimb. Osteochondral fragments were successfully removed via a palmar/plantar arthroscopic approach in all horses. Three horses returned to previous levels of athletic performance; 1 horse was used for trail riding instead of reining. Conclusions— Arthroscopy of the palmar/plantar pouch of the PIP joint allowed limited assessment of the joint and removal of osteochondral fragments. Clinical Relevance— Arthroscopy of the palmar/plantar PIP joint pouch for assessment and removal of osteochondral fragments is possible and should be considered when lameness is localized to this joint.     

Hindlimb lameness associated with proximal suspensory desmopathy and injury of the accessory ligament of the suspensory ligament in five horses

The accessory ligament of the hindlimb suspensory ligament arises from the plantar aspect of the calcaneus and fourth tarsal bones and blends with the suspensory ligament in the proximal aspect of the metatarsus. The accessory ligament of the suspensory ligament of both hindlimbs of 12 mature horses, with no history of hindlimb lameness, was assessed ultrasonographically. The ligament comprised linear parallel echoes which were consistently shorter than those of the lateral digital flexor tendon; the dorsal and plantar borders were parallel. Lameness associated with injury of the accessory ligament of the suspensory ligament was identified in 6 of 8 lame hindlimbs of 5 horses, unilaterally in 4 horses and bilaterally in one horse. In all horses there was concurrent proximal suspensory desmopathy. There was localised oedematous swelling on the distal medial aspect of the chestnut extending distally in 2 horses. Lameness was best identified when the horses were ridden. Perineural analgesia of the deep branch of the lateral plantar nerve abolished lameness in 3 horses but perineural analgesia of the tibial nerve was required to abolish lameness in the hindlimb with injury of the accessory ligament of the suspensory ligament in 2 horses. Injury of the accessory ligament of the suspensory ligament was characterised by marked decrease in echogenicity of the ligament and loss of parallel alignment of the linear echoes, which were shorter than normal in longitudinal images.     

Management of hindlimb proximal suspensory desmopathy by neurectomy of the deep branch of the lateral plantar nerve and plantar fasciotomy: 155 horses (2003-2008)

Reasons for performing study: Neurectomy of the deep branch of the lateral plantar nerve and plantar fasciotomy have become accepted as methods of treatment of proximal suspensory desmopathy (PSD), but there are limited long‐term studies documenting the outcome. Objectives: To describe long‐term follow‐up in horses with PSD alone or with other injuries contributing to lameness and poor performance, including complications, following neurectomy and fasciotomy. Methods: Follow‐up information was acquired for 155 horses that had undergone neurectomy and fasciotomy for treatment of PSD between 2003 and 2008. Success was classified as a horse having been in full work for >1 year post operatively. Horses were divided into 3 groups on the basis of the results of clinical assessment and diagnostic analgesia. Horses in Group 1 had primary PSD and no other musculoskeletal problem. Horses in Group 2 had primary PSD in association with straight hock conformation and/or hyperextension of the metatarsophalangeal joint. Horses in Group 3 had PSD and other problems contributing to lameness or poor performance. Results: In Group 1, 70 of 90 horses (77.8%) had a successful outcome, whereas in Group 3, 23 of 52 horses (44.2%) returned to full function for >1 year. Complications included iatrogenic damage to the plantar aspect of the suspensory ligament, seroma formation, residual curb‐like swellings and the development of white hairs. All horses in Group 2 remained lame. Conclusions and clinical relevance: There is a role for neurectomy of the deep branch of the lateral plantar nerve and plantar fasciotomy for long‐term management of hindlimb PSD, but a prerequisite for successful management requires recognition of risk factors for poor outcome including conformation features of straight hock or fetlock hyperextension.     

Metacarpophalangeal Joint Synovial Pad Fibrotic Proliferation in 63 Horses

Medical records, radiographs, and sonograms of 63 horses with metacarpophalangeal joint synovial pad proliferation were examined retrospectively. All horses had lameness, joint effusion, or both signs associated with one or both metacarpophalangeal joints. Bony remodeling and concavity of the distodorsal aspect of the third metacarpal bone (Mc3) just proximal to the metacarpal condyles was identified by radiography in 71 joints (93%); 24 joints (32%) had radiographic evidence of a chip fracture located at the proximal dorsal aspect of the proximal phalanx. Fifty-four joints (71%) were examined by ultrasound. The mean ± SD sagittal thickness of the synovial pad was 11.3 ± 2.8 mm. Seventy-nine percent of the horses had single joint involvement with equal distribution between the right and left forelimbs. Sixty-eight joints in 55 horses were treated by arthroscopic surgery. Sixty joints (88%) had debridement of chondral or osteochondral fragmentation from the dorsal surface of Mc3 beneath the synovial pad and 30 joints (44%) had a bone chip fracture removed from the medial or lateral proximal dorsal eminence of the proximal phalanx. Complete or partial excision of both medial and lateral synovial pads was completed in 42 joints. Only the medial synovial pad was excised or trimmed in 21 joints, and 5 joints had only the lateral pad removed. Eight joints in eight horses were treated by stall rest, administration of intra-articular medication and systemic nonsteroidal anti-inflammatory drugs. Follow-up information was obtained for 50 horses treated surgically and for eight horses treated medically. Forty-three (86%) that had surgery returned to racing; 34 (68%) raced at an equivalent or better level than before surgery. Three (38%) of the medically treated horses returned to racing; only one horse raced better than the preinjury level. Horses that returned to racing at a similar or equal level of performance were significantly younger in age than horses returning at a lower level or not racing (P≤.05). Overall, horses with synovial pad proliferation treated by arthroscopic surgery had a good prognosis for return to racing at a level equal or better than before injury.     

Osteitis of the axial border of the proximal sesamoid bones in horses: eight cases (1993-1999).

OBJECTIVE: To determine clinical, radiographic, and scintigraphic abnormalities in and outcome of horses with septic or nonseptic osteitis of the axial border of the proximal sesamoid bones. DESIGN: Retrospective study. ANIMALS: 8 horses. PROCEDURE: Data collected from medical records included signalment; history; horse use; severity and duration of lameness; results of perineural anesthesia, radiography, ultrasonography, and scintigraphy; and outcome following surgery. RESULTS: Five horses did not have any evidence of sepsis; the other 3 had sepsis of the metacarpophalangeal or metatarsophalangeal joint or the digital synovial sheath. All horses had a history of chronic unilateral lameness. Three of 5 horses improved after diagnostic anesthesia of the metacarpophalangeal or metatarsophalangeal joint; the other 2 improved only after diagnostic anesthesia of the digital synovial sheath. Nuclear scintigraphy was beneficial in localizing the source of the lameness to the proximal sesamoid bones in 4 horses. Arthroscopy of the palmar or plantar pouch of the joint or of the digital synovial sheath revealed intersesamoidean ligament damage and osteomalacia of the axial border of the proximal sesamoid bones in all horses. All 5 horses without sepsis and 1 horse with sepsis returned to their previous uses. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that osteitis of the axial border of the proximal sesamoid bones is a distinct entity in horses that typically is associated with inflammation of the associated metacarpointersesamoidean or metatarsointersesamoidean ligament and may be a result of sepsis or nonseptic inflammation. Arthroscopic debridement may allow horses without evidence of sepsis to return to their previous level of performance.     

Osteomyelitis secondary to trauma involving the proximal end of the radius in horses: five cases (1987-2001)

OBJECTIVE: To determine clinical, radiographic, and scintigraphic abnormalities in and treatment and outcome of horses with trauma-induced osteomyelitis of the proximal aspect of the radius. DESIGN: Retrospective study. ANIMALS: 5 horses. PROCEDURE: Data collected from the medical records included signalment; history; horse use; degree of lameness; radiographic, ultrasonographic, and scintigraphic findings; treatment; and outcome. RESULTS: Duration of lameness prior to referral ranged from 14 to 60 days. Mean severity of lameness was grade 3 of 5, and all horses had a single limb affected. All horses had signs of pain during elbow joint manipulation and digital palpation over the lateral aspect of the proximal end of the radius. Radiographic lesions consisted of periosteal proliferation, osteolysis, and subchondral bone lysis. Scintigraphy in 3 horses revealed intense pharmaceutical uptake diffusely involving the proximal end of the radius. Two horses had sepsis of the elbow joint. All horses were treated with antimicrobials long-term; 1 horse was also treated by local perfusion of the radial medullary cavity through an indwelling cannulated screw. At follow-up, all horses had returned to their previous function. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that osteomyelitis of the proximal end of the radius can result from a traumatic injury to the antebrachium. Because lesions may be an extension of septic arthritis, a thorough examination of the wound area and elbow joint is recommended. Prolonged systemic antimicrobial treatment can result in a successful outcome.     

Removal of large fragments of the extensor process of the distal phalanx via arthrotomy in horses: 14 cases (1992-1998)

OBJECTIVE: To evaluate the outcome of horses with large fragments of the extensor process of the distal phalanx that were removed by use of arthrotomy. DESIGN: Retrospective study. ANIMALS: 14 horses with large fragments of the extensor process of the distal phalanx. PROCEDURE: Medical records for horses with large fragments of the extensor process that were removed by use of arthrotomy were reviewed. Data retrieved from medical records included signalment, use of horse, affected limb, lameness history, lameness examination findings, radiographic findings, surgical technique, and outcome. Follow-up evaluation was obtained by telephone interview. RESULTS: Most affected horses were < 5 years old and had a history of chronic lameness. Lameness grade ranged from 1/5 to 4/5. Fragments involved 20 to 45% of the dorsopalmar articular surface of the distal phalanx. Eight of 14 horses had a successful outcome. Outcome was not associated with age, duration or severity of lameness, or fragment size. CONCLUSIONS AND CLINICAL RELEVANCE: Despite involvement of a large portion of the articular surface and use of arthrotomy, joint instability and permanent soft tissue injury was not a problem in most horses. Outcome may be improved by selection of horses with lameness of < 2 years' duration and careful management after surgery. A fair prognosis may be anticipated for removal of large fragments of the extensor process via arthrotomy.     

Qualitative and quantitative documentation of the racing performance of 461 Thoroughbred racehorses after arthroscopic removal of dorsoproximal first phalanx osteochondral fractures (1986-1995)

The purpose of this study was to examine the longevity of postoperative careers and quality of performance of 461 Thoroughbred racehorses after arthroscopic removal of dorsoproximal first phalanx (P1) osteochondral fractures. Six hundred and 59 dorsoproximal P1 chip fractures were removed arthroscopically from 574 joints in 461 horses presented for lameness or decreased performance attributed to the chip fractures. Radiological and arthroscopic examination revealed an average of 1.43 fragment sites/horse, 1.15 fragment sites/joint and 1.25 affected joints/horse. Eighty-nine percent of the horses (411/461) raced after surgery and 82% (377/461) did so at the same or higher class. Fifty horses did not race after surgery. Sixty-eight percent of the horses raced in a Stake or Allowance race postoperatively. Data, previously undocumented, establishes that the quantity and quality of performance is not diminished after arthroscopic treatment of dorsoproximal P1 fragmentation. Surgical removal of chip fractures is a means of preserving the economic value of an injured Thoroughbred, allowing a rapid and successful return to racing at the previous level of racing performance.     

Desmitis of the straight sesamoidean ligament in horses: 9 cases (1995-1997)

OBJECTIVE: To determine clinical signs, diagnostic findings, and outcome for horses with desmitis of the straight sesamoidean ligament (SSL) near its insertion on the middle phalanx. DESIGN: Retrospective study. ANIMALS: 9 horses. PROCEDURE: Medical records were reviewed, and information on signalment, history, clinical signs, diagnostic findings, and treatment was obtained. Follow-up information was obtained through telephone conversations with owners. RESULTS: In all horses, the diagnosis was made by use of high-resolution ultrasonography. Seven horses had moderate lameness on initial examination; lameness was exacerbated in 6 horses following flexion of the distal limb joints. The cause of lameness could not be determined on the basis of clinical signs, and diagnostic local anesthesia was necessary to localize the source of lameness to the distal portion of the limb. Five horses had forelimb involvement (1 bilateral), and 4 had hind limb involvement (1 bilateral). Treatment consisted primarily of a 6-month rest and rehabilitation program. Six of the 9 horses were able to return to their intended use. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that injury to the SSL proximal to its insertion on the middle phalanx should be considered as a possible cause of lameness in horses, particularly performance horses, with lameness localized to the distal portion of the forelimb or hind limb that do not have any radiographic abnormalities. High-resolution ultrasonography was necessary to make the diagnosis. Horses with an acute injury appeared to have a reasonable chance of responding to treatment and returning to their intended use.     

Arthrodesis of the Distal Interphalangeal Joint in Two Horses Using Three Parallel 5.5-mm Cortical Screws

The distal interphalangeal joint was successfully arthrodesed in two horses using three parallel 5.5-mm cortical screws and an autogenous cancellous bone graft. The screws were directed from the palmar proximal border of the second phalanx dorso-distally across the joint space and into the third phalanx. The technique was first developed on a normal horse. The second horse, a clinical case, ruptured its deep digital flexor tendon with complete luxation of the distal interphalangeal joint. Bony fusion of the distal interphalangeal joint occurred in both horses, but both also had residual lameness at a walk. Twenty-one months after the arthrodesis procedure, the clinical patient died from complications related to a subsolar abscess in the operated limb.     

Long‐Term Outcome after Arthroscopic Debridement of Distal Phalanx Extensor Process Fragmentation in 13 Horses

Objective— To report long-term outcome after arthroscopic removal of fragmentation of the extensor process of the distal phalanx in horses.
Study Design— Case series.
Animals— Adult horses (n=13).
Methods— Medical records (2003–2004) of horses that had arthroscopic debridement of fragmentation of the extensor process of the distal phalanx were reviewed. Inclusion criteria included: lameness localized to the foot, fragmentation of the extensor process of the distal phalanx debrided arthroscopically, and a follow-up period of ≥4 years.
Results— Of the 13 horses, lameness was resolved in 11 (85%) initially but distal interphalangeal joint pain recurred in 2 (15%) within 1 year of surgery. Three (23%) other horses were retired because of lameness at other sites during the follow-up period resulting in 46% (6/13) being not lame and in full work after 4 years. Substantial changes were identified at surgery in the contralateral joint of 7 horses, even when fragments were only present unilaterally.
Conclusions— Arthroscopic debridement of fragmentation of the extensor process of the forelimb distal phalanx has a good short-term prognosis for resolution of lameness and return to work but a more guarded prognosis for long-term soundness.
Clinical Relevance— These results allow for more accurate prognostication preoperatively and may support early debridement of fragmentation of the extensor process of the distal phalanx.     

Using magnetic resonance imaging to diagnose nondisplaced fractures of the second phalanx in horses

Two horses presented with a history of severe lameness that was localised to the area around the second phalanx (P2) of one forelimb. Radiographs of the second phalanx of both horses were unremarkable, apart from some smooth periosteal new bone production on the dorsum of P2. Magnetic resonance imaging revealed a non-displaced fracture of P2 in both horses. One horse was euthanased because of a poor prognosis for racing, but the second horse was treated conservatively and salvaged for breeding. Magnetic resonance imaging is a newer imaging modality in horses and may be useful in diagnosing cases of obscure lameness.     

Management of comminuted fractures of the proximal phalanx in horses: 64 cases (1983-2001)

OBJECTIVE: To report the outcome of surgical treatment of comminuted fractures of the proximal phalanx in horses. DESIGN: Retrospective study. ANIMALS: 64 horses. PROCEDURE: Medical records and radiographs were reviewed to obtain information regarding signalment, fracture classification, and treatment. Follow-up information was obtained by telephone conversation or evaluation of production records. RESULTS: Thirty-eight horses had moderately comminuted fractures of the proximal phalanx. Two horses were euthanatized immediately. Fractures of the proximal phalanx in 36 horses were repaired with open reduction and internal fixation with a successful outcome in 33 (92%) horses. Reconstruction of the fracture was performed in most horses by use of a long curved incision, transection of the collateral ligament of the metacarpophalangeal or metatarsophalangeal joint, and open exposure of the proximal articular surface of the proximal phalanx. Twenty-six horses had severely comminuted fractures of the proximal phalanx. Six horses were euthanatized immediately. One horse was euthanatized after 9 days of treatment with a cast alone. Severely comminuted fractures of the proximal phalanx in 13 horses were treated with an external skeletal fixation device, and fractures healed in 8 of those horses. Six horses with severely comminuted fractures of the proximal phalanx were treated with transfixation pins incorporated into a fiberglass cast, and fractures healed in 4 horses. CONCLUSIONS AND CLINICAL RELEVANCE: Moderately comminuted fractures of the proximal phalanx can be successfully repaired; however, fractures that are too severe to permit accurate reconstruction of the fragments remain difficult to treat and horses have only a fair prognosis for survival.     

Osteochondral fragmentation of the palmarolateral/plantarolateral aspect of the distal phalanx in four horses: A novel location

Four horses presenting for lameness were diagnosed with unilateral osteochondral fragmentation (OCF) of the palmarolateral/plantarolateral aspect of the distal phalanx within the distal interphalangeal joint (DIPJ). Histological evaluation of one case supported a diagnosis of osteochondritis dissecans (OCD), with patient age and history from two cases suggesting a traumatic origin. Lesion appearance on conventional radiography, computed tomography (CT), nuclear scintigraphy and magnetic resonance imaging (MRI) are described. Fragmentation was best identified on dorsal 65° proximal-palmaro/plantarodistal oblique (D65°PrPDiO/D65°PrPlDiO) and dorsal 65° proximal-palmaro/plantarodistal lateral oblique (D65°Pr45°L-PDiMO/D65°Pr45°L-PlDiMO) radiographic projections of the foot, but articular pathology appeared more severe on cross-sectional imaging modalities. In all cases, lameness was refractory to conservative management. Arthroscopic evaluation of the DIPJ was performed in three horses, although the lesion was inaccessible in two. In one horse, access to the lesion was possible due to increased joint laxity, presumably due to concurrent soft tissue injury. One horse was euthanased after failed conservative management, one was pasture sound following palmar digital neurectomy 12 months after initial presentation, one returned to racing and one was lost to follow-up. Osteochondral fragmentation at this location has not previously been described, treatment options are limited and the prognosis appears to be poor.     

Pathological fracture through a subchondral bone cyst in the proximal phalanx of a horse

A 12‐year‐old Morgan broodmare presented for a nonweightbearing right forelimb lameness. Radiography and computed tomography confirmed the presence of a pathological fracture of the proximal first phalanx through a large subchondral bone cyst (SBC) in the right forelimb and a large SBC in the proximal first phalanx of the left forelimb. Surgical repair of the large palmar medial eminence fracture of the proximal first phalanx fracture was performed using bone screws placed in lag fashion placed through stab incisions after debridement and bone grafting of the SBCs. Approximately 6 months after surgery the mare was ambulating comfortably at pasture. This case report describes a fracture through a large subchondral bone cyst in a horse despite chronicity and ongoing bone remodelling. Careful consideration regarding exercise or use should be considered in horses with large SBCs.     

Incomplete Longitudinal Fracture of the Proximal Palmar Cortex of the Third Metacarpal Bone in Horses

Seven horses, 2 to 4 years of age, were examined because of moderate-to-severe forelimb lameness, mild effusion of the middle carpal joint (3 horses), and pain on palpation of the origin of the suspensory ligament (4 horses). The lameness was abolished by anesthetic infiltration of the middle carpal joint in six horses. In four of them, a high palmar nerve block also abolished the lameness. A linear radiolucency in the proximal end of the third metacarpal bone (McIII) was interpreted as an incomplete longitudinal fracture. In one horse, distinct intramedullary sclerosis limited to the palmar cortex was indicative of an incomplete fracture confined to the palmar cortex. No osteoproliferative lesions were identified on the dorsal cortex of any of the horses. Surgical treatment with cortical screws in lag fashion accompanied by a rest period was successful in one horse. In four horses, rest for at least 3 months resulted in clinical soundness. In two horses, a shorter rest period resulted in recurrence of the lameness even though the horses were sound when put back into training. Careful clinical and radiographic examinations helped differentiate incomplete longitudinal fractures from lesions involving the carpus and proximal aspect of the suspensory ligament.     

Retrospective analysis of distal limb conformation and lameness in mature horses after desmotomy of the accessory ligament of the deep digital flexor tendon for management of a flexural deformity

Mature horses that present with flexural deformity of the distal interphalangeal joint and lameness isolated to the foot may obtain long‐term benefits from desmotomy of the accessory ligament of the deep digital flexor tendon (ALDDFT). This retrospective analysis of medical records and radiographs included 13 horses, aged ≥2 years, presented for lameness isolated to the hoof region and diagnosed with flexural deformity of the distal interphalangeal joint. Radiographic angles of the hoof and distal interphalangeal joint and lameness scores were compared before and after desmotomy of the ALDDFT. Follow‐up data including the ability to perform the intended use were obtained at least one year after surgery. There was improvement in the angle between the dorsal aspect of the third phalanx and the weightbearing surface of the hoof, improved alignment between the dorsal hoof wall and dorsal aspect of the third phalanx, and improved alignment of the distal interphalangeal joint. Lameness was decreased in 9/13 horses and 10/13 horses were performing at their level of intended use. Evidence of improved hoof conformation and lameness following desmotomy of the ALDDFT in lame horses with flexural deformity of the distal interphalangeal joint would indicate this procedure should be considered in mature horses.