Surgical management of marginal tears/avulsions of the suspensory ligament branches in 29 Thoroughbred racehorses.

BACKGROUND: Suspensory ligament branch injuries are common in horses. Most of these injuries are grouped together and considered as a single pathologic entity. OBJECTIVES: To report a specific injury of the abaxial margin of the suspensory ligament branches and to report its surgical management and outcome. STUDY DESIGN: Retrospective case series. METHODS: All horses with suspensory ligament branch injuries over a 9-year period (2007-2015) were identified. Horses with injuries which, on ultrasonographic examination, appeared to have defects in the abaxial margin of the suspensory ligament branch, that were subsequently confirmed during surgery were selected. RESULTS: Twenty-nine cases fulfilled the inclusion criteria with a specific lesion location on the abaxial margin of the suspensory ligament branch. Nineteen horses raced successfully after surgery, nine returned to training but failed to race and one was lost to follow-up. MAIN LIMITATIONS: The absence of a comparable population of non-surgically managed horses in this study means that the contribution of removing torn tissue cannot confidently be assessed. CONCLUSIONS: The location and morphology of injuries described in this study is consistent, which suggests aetiopathogenic commonality. This case series suggests this type of injury has an identity of its own, differs from other types of suspensory ligament branch injuries and represents a previously undescribed subgroup.

Short frontal plane fractures involving the dorsoproximal articular surface of the proximal phalanx: Description of the injury and a technique for repair.

BACKGROUND: Chip fractures of the dorsoproximal articular margin of the proximal phalanx are common injuries in racehorses. Large fractures can extend distal to the joint capsule insertion and have been described as dorsal frontal fractures. OBJECTIVES: To report the location and morphology of short frontal plane fractures involving the dorsoproximal articular surface of the proximal phalanx and describe a technique for repair under arthroscopic and radiographic guidance. STUDY DESIGN: Single centre retrospective case study. METHODS: Case records of horses with frontal plane fractures restricted to the dorsoproximal epiphysis and metaphysis of the proximal phalanx referred to Newmarket Equine Hospital were retrieved, images reviewed and lesion morphology described. A technique for repair and the results obtained are reported. RESULTS: A total of 22 fractures in 21 horses commencing at the proximal articular surface exited the dorsal cortex of the proximal phalanx distal to the metacarpophalangeal/metatarsophalangeal joint capsule in 17 hind- and five forelimbs. All were in Thoroughbred racehorses. In 16 cases these were acute racing or training injuries; 20 fractures were medial, one lateral and one was midline. All were repaired with a single lag screw using arthroscopic and radiographically determined landmarks. A total of 16 horses raced after surgery with performance data similar to their preinjury levels. MAIN LIMITATIONS: The study demonstrates substantial morphological similarities between individual lesions supporting a common pathophysiology, but does not identify precise causation. There are no cases managed differently that might permit assessment of the comparative efficacy of the treatment described. CONCLUSIONS: Short frontal plane fractures involving the dorsoproximal margin of the proximal phalanx that exit the bone distal to the metacarpophalangeal/metatarsophalangeal joint capsule have substantial morphological similarities, are amenable to minimally invasive repair and carry a good prognosis for return to training and racing.

A new technique for subtotal (cranial wedge) ostectomy in the treatment of impinging/overriding spinous processes: description of technique and outcome of 25 cases.

REASONS FOR PERFORMING STUDY: Surgical management for overriding spinous processes of the thoracolumbar vertebrae (SPs) is often favoured when conservative therapies have failed, pathology is severe, or in competition horses constrained by drug withdrawal periods. OBJECTIVES: To evaluate whether subtotal (cranial wedge) ostectomy represents an effective treatment for overriding SPs, with short surgery time and low complication rates, maintains the contour of the spine and produces a functionally and cosmetically better outcome than previously reported surgical techniques for management of overriding/impinging SPs. STUDY DESIGN: Retrospective study. METHODS: A new technique is described and records were retrieved for 25 cases that had undergone the procedure at Newmarket Equine Hospital between 2009 and 2011. Case records were evaluated for anamnesis, clinical findings and details of surgical and post operative management. Outcome of surgery was assessed by telephone questionnaire with owners, relating to both functional and cosmetic results. RESULTS: Of cases treated using the described technique, 78.9% had resolution of clinical signs and returned to full work and a further 18.2% were improved. Outcome was unrelated to number of SPs resected or mean radiographic grade of impingement. Cosmetic outcome was described as excellent in 81.8% and good in the remainder. Surgery time ranged from 20 to 70 (median 30) min and there were no intra- or post operative complications. CONCLUSIONS: In contrast to previously described amputation techniques, subtotal (cranial wedge) ostectomy removes only impinging portions of SPs. General anaesthesia and lateral recumbency facilitate access and enable a short surgery time. The procedure maintains the contour of the back and has fewer complications, but produces functional outcomes similar to more invasive procedures.

Identification and treatment of osteochondritis dissecans of the distal sagittal ridge of the third metacarpal bone.

REASONS FOR PERFORMING STUDY: Osteochondritis dissecans (OCD) of the distal sagittal ridge of the third metacarpal bone (McIII) has not previously been described in the literature. OBJECTIVES: To describe the clinical, radiological and arthroscopic features of OCD of the distal sagittal ridge of the McIII and to report outcome in a series of cases. STUDY DESIGN: Retrospective case series. METHODS: Case records and images of horses with OCD of the distal sagittal ridge of the McIII admitted to a single referral centre between February 2006 and February 2013 were reviewed. Follow-up information was obtained by telephone questionnaire and/or racing performance. RESULTS: Osteochondritis dissecans of the distal sagittal ridge of the McIII was found in 16 lame horses; 9 unilaterally and 7 bilaterally. Lesions were consistently identified with flexed lateromedial radiographs and in 21 joints in dorsopalmar projections also. These were arthroscopically accessible from the dorsal compartment with metacarpophalangeal joints maximally flexed. This permitted fragment removal and lesion debridement. Thirteen of 14 horses with follow-up of ≥12 months post surgery performed athletically including 11 of 12 Thoroughbreds that raced. CONCLUSIONS: Unlike more proximal lesions, OCD of the distal sagittal ridge appears to affect the McIII preferentially. Lesions were identified on dorsopalmar and flexed lateromedial radiographs only and are amenable to arthroscopic surgery. Clinicians should be aware of the potential for OCD to affect the distal sagittal ridge of the McIII together with the radiographic projections needed to identify its presence. A modified arthroscopic approach to the dorsal metacarpophalangeal joint is necessary in order to access lesions.

Frontal plane fractures of the accessory carpal bone and implications for the carpal sheath of the digital flexor tendons.

REASONS FOR PERFORMING STUDY: Accurate radiological and ultrasonographic descriptions of frontal plane fractures of the accessory carpal bone (ACB) are lacking, and implications of these fractures for the carpal sheath and its contents have not previously been reported. OBJECTIVES: Aims were as follows: 1) to describe the location and radiological features of frontal plane fractures of the ACB; 2) to document communication of displaced fractures with the carpal sheath and consequent injury to the deep digital flexor tendon (DDFT); 3) to describe ultrasonographic identification of lesions; and 4) to report tenoscopic evaluation and treatment. STUDY DESIGN: Retrospective case series. METHODS: Analysis of frontal plane fractures of the ACB referred to a single hospital between 2006 and 2012, including review of radiographic, ultrasonographic and tenoscopic images. RESULTS: Nine fractures were identified, of which 8 displaced fractures all communicated with the carpal sheath. Comminuted fragments and/or protruding fracture margins lacerated the lateral margin of the enclosed DDFT. This was identifiable ultrasonographically and confirmed at tenoscopy in 7 cases. Treatment in these horses consisted of removal of torn tendon tissue together with fragmentation and protuberant fracture edges, and 7 of 7 cases returned to work. One horse with a nondisplaced fracture was managed with immobilisation; the fracture healed, and the horse returned to work. One horse with a displaced fracture was retired to stud. CONCLUSIONS: Frontal plane fractures of the ACB occur palmar to the groove in its lateral margin for the tendon of insertion of ulnaris lateralis. Comminuted fragments can displace distally within the carpal sheath to a mid-metacarpal level or abaxially to lie extrathecally, lateral to the parent bone. Displaced fractures communicate with the carpal sheath and traumatise the DDFT.

Soft tissue injuries of the tarsocrural joint: a retrospective analysis of 30 cases evaluated arthroscopically.

REASONS FOR PERFORMING THE STUDY: Intra-articular soft tissue injuries of the equine tarsocrural joint have been poorly defined. METHODS: All horses that underwent arthroscopic surgery of a tarsocrural joint over a 10 year period were identified. Those with primary intra-articular soft tissue injuries were selected for inclusion and the cases evaluated retrospectively. RESULTS: Two hundred and eighty-one horses underwent tarsocrural joint arthroscopy during the study period, 30 of which met the inclusion criteria (30 joints). A combination of soft tissue lesions was more common than injury to a single structure. Injuries involved the joint capsule (n = 25), collateral ligaments (n = 20), dorsal plica (n = 8) and open communication between the tarsocrural joint and extensor bundle (n = 7). Following arthroscopic surgery and rehabilitation, 81% of horses were able to return to their previous function. CONCLUSION: Intra-articular soft tissue injuries of the tarsocrural joint may be associated with localising clinical signs of inflammation. This series represented 11% of the total number of arthroscopic procedures undertaken on that joint in a single referral hospital. Arthroscopic surgery allows accurate definition of the injuries and facilitates lesion management. Case outcome following arthroscopic debridement and a subsequent period of rehabilitation is favourable. POTENTIAL RELEVANCE: In lame horses with clinical signs localised to the tarsocrural joint, disrupted intra-articular soft tissues should be considered in the list of differential diagnoses. Attending clinicians should consider arthroscopic evaluation in cases where primary intra-articular soft tissue injuries are suspected to be causative.

Tenosynovitis of the carpal sheath of the digital flexor tendons associated with tears of the radial head of the deep digital flexor: observations in 11 horses.

REASONS FOR PERFORMING STUDY: Tears of the radial head of the deep digital flexor (DDF) have not previously been documented. OBJECTIVES: To describe the presentation, clinical, ultrasonographic and tenoscopic features associated with tears of the radial head of the DDF and to report the results of treatment. HYPOTHESES: Tears of the radial head of the DDF cause lameness and distension of the carpal sheath of the digital flexor tendons. Removal of disrupted tissue that is extruded into the sheath can result in clinical resolution and restoration of function. METHODS: Case records and diagnostic images of horses in which tearing of the radial head of the DDF was diagnosed were reviewed retrospectively and follow-up information obtained. RESULTS: Eleven cases were identified. Clinical, ultrasonographic and tenoscopic commonality was recorded and treatment techniques were documented. All cases returned post operatively to pre-injury levels of work. CONCLUSION: Tearing of the radial head of the DDF is a clinical entity with consistent diagnostic features. Tenoscopic removal of the torn tissue is associated with a good outcome. POTENTIAL RELEVANCE: Clinicians evaluating lame horses should include tearing of the radial head of the DDF as a differential diagnosis in animals with distended carpal sheaths. Tenoscopic surgery is a recommended treatment.

Clinical, radiological and ultrasonographic features, treatment and outcome in 22 horses with caudal distal radial osteochondromata.

REASONS FOR PERFORMING STUDY: Although a well recognised clinical entity, only small numbers of osteochondromata on the caudal distal radius have previously been published and its occurrence in young racing Thoroughbreds has not previously been reported. Identification and management of associated lesions in the deep digital flexor tendon have received scant attention in the literature. HYPOTHESIS: Osteochondromata of the caudal distal radius occur commonly in young racing Thoroughbreds. They vary in size and location, sagittally and proximodistally, but the majority cause impingement damage to the deep digital flexor tendon. METHODS: Case records and diagnostic images of horses with osteochondromata of the caudal distal radius were reviewed retrospectively and follow-up information obtained. RESULTS: Twenty-five osteochondromata were identified in 22 horses, 19 of which were Thoroughbreds. All osteochondromata were metaphyseal. Twenty-two were in the middle one-third of the bone and laceration of the adjacent deep digital flexor tendon was identified in 21 limbs. Treatment in all cases consisted of removal of the osteochondroma with debridement of the deep digital flexor tendon when this was affected. All horses returned to work and none exhibited any evidence of recurrence. CONCLUSION: Osteochondromata of the caudal distal radius occur in young racing Thoroughbreds but are also identified in other horses. They have a consistent metaphyseal location and most are found in the middle one-third of the radius. Size varies, but most cause laceration of the adjacent deep digital flexor tendon. Treatment by removal of the mass and debridement of the tendon is associated with a good prognosis. POTENTIAL RELEVANCE: Osteochondromata of the caudal distal radius are an important cause of tenosynovitis of the carpal sheath of the digital flexor tendons in young racing Thoroughbreds. When present in the most common location of the middle one-third of the bone, they are likely to cause impingement damage to the deep digital flexor tendon. Tenoscopic surgery offers a good prognosis.

Injuries of the calcaneal insertions of the superficial digital flexor tendon in 19 horses.

REASONS FOR PERFORMING STUDY: Injuries of the calcaneal insertions of the superficial digital flexor tendon and their relationship to displacement of the tendon from the calcaneus have not previously been reported. OBJECTIVES: To describe findings made on clinical cases with disruption of the calcaneal insertions of the superficial digital flexor tendon (SDFT) including observations on their role in horses with unstable subluxation of the tendon. To describe novel surgical techniques and the results of treatment. HYPOTHESES: Disruption of the calcaneal insertions of the SDFT is associated with lameness and distension of the calcaneal bursa. Unstable displacement of the SDFT from the calcaneus is a more complex injury than incomplete disruption of one of its calcaneal insertions. METHODS: The case records and diagnostic images of horses with lesions involving the calcaneal insertions of the SDFT, which were confirmed by endoscopic evaluation of calcaneal bursa between 2005 and 2009, were reviewed. RESULTS: Nineteen horses were identified including 7 that had unstable displacement of the tendon from the calcaneus. Following endoscopic surgery, 9 of 12 horses with stable tendons and 6 of 7 horses with unstable displaced SDFTs returned to work. CONCLUSION: Tearing of the calcaneal insertions of the SDFT is associated with lameness and distension of the calcaneal bursa; endoscopic removal of the torn tissue carries a good prognosis. Horses with unstable displacement of the tendon have also disruption of the tendon fibrocartilage cap. Removal of this results in stable subluxation and can return horses to athletic activity. Both lesions can be detected by preoperative ultrasonography. POTENTIAL RELEVANCE: Tearing of the calcaneal insertions of the SDFT should be included in the differential diagnoses of lame horses with distended calcaneal bursae. Tearing of the tendon fibrocartilage cap in horses with unstable displacement of the SDFT is a plausible explanation of the clinical features of the injury and explains previously unreliable results of reconstructive surgeries. Subtotal resection is a technically demanding technique but appears to offer an improved prognosis.

Synoviocoeles associated with the tarsal sheath: description of the lesion and treatment in 15 horses.

REASONS FOR PERFORMING STUDY: To describe the presentation, clinical, ultrasonographic and endoscopic features associated with a defect in the tarsal sheath wall, to define the cavity created and to describe a method of treatment. HYPOTHESIS: So called 'false thoroughpins' can be caused by defects in the tarsal sheath wall creating a one way valve effect, removal of which could be therapeutic. METHODS: Case records and diagnostic images of horses with synoviocoeles associated with the tarsal sheath were reviewed retrospectively and follow-up information obtained. RESULTS: Synoviocoeles were diagnosed in 15 horses. All were managed similarly and 10 horses had clinical resolution and returned to work. CONCLUSION: Terminology previously used to describe lesions involving the tarsal sheath does not define accurately the condition described and the term synoviocoele is recommended. Endoscopic enlargement of the sheath wall defect produced good clinical results in 10/15 horses. POTENTIAL RELEVANCE: Clinicians should include synoviocoele in the list of differential diagnoses of fluid filled cavities associated with the tarsal sheath and should consider endoscopic surgery as a treatment modality.

Arthroscopic diagnosis and treatment of intra-articular insertional injuries of the suspensory ligament branches in 18 horses.

REASONS FOR PERFORMING STUDY: Clinical association between the branches of insertion of the suspensory ligament (SL) and metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints has been reported. However, there has been no assessment of the lengths of the SL branches which are subsynovial with respect to the joints or reports of involvement of the MCP/MTP joints in injuries of the SL branches. OBJECTIVES: To establish proportions of SL branches subsynovial with respect to the MCP/MTP joints and report clinical and arthroscopic findings in horses with desmitis of SL branches identified as having an articular component to the lesion. HYPOTHESIS: Arthroscopic surgery enables identification and potential treatment of intra-articular injuries of SL branches. METHODS: Twelve forelimbs and 13 hindlimbs were dissected and the total and subsynovial lengths of the SL branches recorded. Case records of horses with intra-articular injuries of the SL branches were reviewed and 18 animals identified. Diagnostic information and arthroscopic findings were recorded and results of treatment determined by telephone follow-up. RESULTS: Of SL branches, 28.45% in the forelimb and 29.56% in the hindlimb were subsynovial to the MCP and MTP joints. All animals with intra-articular lesions of the SL branch were lame and had distension of the affected MCP/MTP joint. In 16 horses (17/22 branches), there was palpable thickening of the affected SL branch. Disrupted infrastructure was evident ultrasonographically in 15/17 branches and involvement of the dorsal articular surface of the ligament was predicted in 12/17 branches. Following arthroscopic intervention, 13 horses returned to work at a level equal to or greater than that achieved prior to injury and 2 returned to work at a lower level. Three horses incurred separate injuries and were retired or subjected to euthanasia. CONCLUSIONS: Articular involvement should be considered in animals with injuries of an SL branch and concurrent distension of the MCP/MTP joint. Arthroscopy is necessary to identify such lesions confidently and to direct case management. POTENTIAL RELEVANCE: Arthroscopy of the MCP/MTP joints can make a positive contribution to the assessment and management of some SL branch injuries.