Superior check ligament desmotomy for treatment of superficial digital flexor tendonitis in Thoroughbred and Standardbred horses

Summary Bilateral superior check ligament desmotomy was performed on 31 Thoroughbred and 17 Standardbred horses as the sole method of treatment for superficial digital flexor tendonitis. Horses resumed racing between 6 and 19 months after surgery. Horses that were able to compete in 5 or more races without injury to the tendon again were considered to have had a successful return to racing. Twenty-five Thoroughbreds were suitable for later study and 13 of these (52%) raced on 5 or more occasions. Fifteen Standardbreds were suitable for later study and 10 of these (66%) raced on 5 or more occasions. Within the racing industry it is generally thought that about 20 to 30% of horses with superficial digital flexor tendonitis can return to racing after a prolonged rest. The results of this study suggest that bilateral superior check ligament desmotomy may improve the prognosis for a horse returning to racing after injury to the superficial digital flexor tendon.     

Superficial digital flexor tendonitis in Thoroughbred race horses: outcome following non-surgical treatment and superior check desmotomy

Objective This study documents the results of non-surgical treatment and treatment by superior check desmotomy in Thoroughbred racehorses with superficial digital flexor (SDF) tendonitis. Design A prospective study was made of 124 thoroughbred racehorses with unilateral or bilateral SDF tendonitis. Procedure The flexor tendons were assessed by physical and ultrasonographic examination before treatment, and the lesions detected in affected tendons were characterised according to lesion type, length and cross-sectional area. Ninety three horses were managed non-surgically and 31 by superior check desmotomy. Recurrent or new injuries were defined as injuries affecting a previously injured superficial digital flexor tendon, the contralateral SDF tendon, or the suspensory ligament (interosseous muscle) in either forelimb. Results No statistically significant difference was found in ultrasonographic lesion severity between treatment groups. Horses managed by superior check desmotomy were 1.3 times more likely to complete five or more races than horses managed non-surgically (95% confidence limits 0.93–1.82). Horses treated surgically were 1.2 times more likely to develop recurrent or new injuries after returning to training than horses managed non-surgically (95% CL 0.95–1.55). Horses under-going superior check desmotomy were 5.5 times more likely to develop suspensory desmitis than horses treated non-surgically (95% CL 1.13–26.4). There was no difference in the time to recurrent or new injury between treatment groups. Conclusion There was no statistically significant difference between treatment groups in the proportions of horses able to complete five or more races after an episode of superficial digital flexor tendonitis. Superior check desmotomy did not appear to offer an advantage over non-surgical treatment in preventing recurrent or new injuries in Thoroughbred racehorses. Horses undergoing superior check desmotomy appeared to be at greater risk of developing suspensery ligament injuries than horses managed non-surgically.     

Lameness in 46 horses associated with deep digital flexor tendonitis in the digit: diagnosis confirmed with magnetic resonance imaging

REASONS FOR PERFORMING STUDY: The differential diagnosis of foot pain has long proved difficult and the use of magnetic resonance imaging (MRI) offers the opportunity to further the clinical understanding of the subject. OBJECTIVES: To determine the incidence of deep digital flexor tendon (DDFT) injuries in a series of 75 horses with lameness associated with pain localised to the digit, with no significant detectable radiographic or ultrasonographic abnormalities, using MRI; and to describe a variety of lesion types and relate DDF tendonitis with anamnesis, clinical features, response to local analgesic techniques and nuclear scintigraphic and ultrasonographic findings. METHODS: All horses undergoing MRI of the front feet between January 2001 and October 2002 were reviewed and those with DDFT injuries categorised according to lesion type; horses with primary tendonitis (Group I) and those with concurrent abnormalities of the navicular bone considered to be an important component of the lameness (Group II). The response to perineural analgesia of the palmar digital nerves and palmar (abaxial sesamoid) nerves, intra-articular analgesia of the distal interphalangeal (DIP) joint and analgesia of the navicular bursa were reviewed. The result of ultrasonography of the pastern and foot was recorded. Lateral, dorsal and solar pool and bone phase nuclear scintigraphic images were assessed subjectively and objectively using region of interest (ROI) analysis. RESULTS: Forty-six (61%) of 75 horses examined using MRI had lesions of the DDFT considered to be a major contributor to lameness. Thirty-two horses (43%) had primary DDFT injuries and 14 (19%) a combination of DDF tendonitis and navicular bone pathology. Lesions involved the insertional region of the tendon alone (n = 3), were proximal to the navicular bone (n = 23) or were at a combination of sites (n = 20). Lesion types included core lesions, focal and diffuse dorsal border lesions, sagittal plane splits, insertional injuries and lesions combined with other soft tissue injuries. Many horses had a combination of lesion types. Lameness was abolished by palmar digital analgesia in only 11 of 46 horses (24%). Twenty-one of 31 horses (68%) in Group I showed > 50% improvement in lameness after intra-articular analgesia of the DIP joint, whereas 11 of 12 horses (92%) in Group II had a positive response. Twelve of 18 horses (67%) in Group I had a positive response to analgesia of the navicular bursa. Nineteen horses had lesions of the DDFT extending proximal to the proximal interphalangeal joint seen using MRI, but these were identified ultrasonographically in only 2 horses. Scintigraphic abnormalities suggestive of DDFT injury were seen in 16 of 41 horses (41%), 8 in pool phase images and 8 in bone phase images. CONCLUSIONS AND POTENTIAL RELEVANCE: DDFT injuries are an important cause of lameness associated with pain arising from the digit in horses without detectable radiographic abnormalities. Lameness is not reliably improved by palmar digital analgesia, but may be improved by intra-articular analgesia of the DIP joint in at least 68% of horses. Ultrasonography is not sensitive in detecting lesions of the DDFT in the distal pastern region, but a combination of pool and bone phase scintigraphic images of the digit is helpful in some horses. Further follow-up information is required to determine the prognosis for horses with lesions of the DDFT in the digit and to establish whether this is related to lesion severity and/or location.     

Superficial digital flexor tendonitis in the horse

The superficial digital flexor tendon (SDFT) is an elastic structure that during maximal exercise appears to operate close to its functional limits. The biomechanical and biochemical responses to exercise, injury, and healing are still poorly understood but ongoing research is providing valuable new information which is addressed in this review. It appears that the SDFT matures early, after which time it has limited ability to adapt to stress and undergoes progressive degeneration. Focal hypocellularity, collagen fibril degeneration, selective fibril loading and alterations in the noncollagenous matrix occur primarily within the central core region of the midmetacarpal segment. Current treatment strategies have had equivocal results in returning animals to optimal athletic activity. To date it would seem that progressive rehabilitation programmes coupled with regular ultrasonographic evaluations are a cost-effective and comparable strategy when compared to surgical treatment methods. Recent interest in pharmacological modulation of intrinsic healing of collagenous structures has led to the investigation of various growth factors as potential therapeutic aids in the healing of tendon injuries. However, one of the major goals in tendon research, and one which holds the most optimism for success in the immediate future, is the prevention of tendon injuries.     

Treatment of septic common digital extensor tenosynovitis by complete resection in seven horses

OBJECTIVE: To describe and evaluate a technique for radical resection of the entire intrathecal component of the common digital extensor tendon (CDET) in horses. STUDY DESIGN: Prospective clinical study. ANIMALS OR SAMPLE POPULATION: Seven client-owned horses. METHODS: Seven horses with wounds that resulted in septic tenosynovitis of the CDET sheath were treated by complete surgical resection of the affected tendon and ablation of the tendon sheath; 5 had previous surgery that was unsuccessful. Time from initial injury to complete resection was 1-22 weeks. In 6 horses, the wound was closed primarily using a closed suction (4 horses), penrose (1), or passive open drainage system (1). In 1 horse, the surgical wound healed by second intention. All horses had postoperative bandaging, antibiotic administration, and physiotherapy. RESULTS: Surgical wounds healed primarily in 6 horses and by second intention in 1 horse. Follow-up (mean, 26.4 months; range, 18-38 months) was available for 6 horses; all returned to their athletic performance level without lameness or gait abnormality. CONCLUSIONS: Complete resection of the CDET was an effective surgical technique for management of chronic septic tenosynovitis. CLINICAL RELEVANCE: Horses with infection of the CDET and its sheath may be returned to long-term soundness without gait abnormality after radical resection.     

Healing characteristics of deep digital flexor tenorrhaphy within the digital sheath of horses

OBJECTIVE: To describe the healing characteristics of deep digital flexor tenorrhaphy within the digital sheath. STUDY DESIGN: Experimental study. ANIMALS: Five mature horses. METHODS: Right thoracic limb, deep digital flexor tenorrhaphy was performed within the digital sheath. Limbs were cast in partial flexion using a short limb cast for 6 weeks. Next, extended heel shoes were used for limb support for 14 weeks. Healing was evaluated by sequential ultrasonographic examinations, and limb use was evaluated by force plate analysis. At 26 weeks, mechanical strength and morphologic characteristics of the repair site were evaluated. RESULTS: Gap (mean, 0.93 cm.) formation was evident in unloaded limbs at 3 weeks. This increased markedly by 6 weeks and was 5 cm at 26 weeks. Demarcation between the deep and superficial flexor tendons decreased as the transected ends adhered to the dorsal surface of the superficial flexor tendon. The intrathecal space was reduced by fibrous tissue. Mean maximum load to failure of the repair tissue was 4,616 +/- 3,556 N, with a mean stress of 12.99 +/- 2.78 MPa. The repair consistently failed at the adhesion between the transected tendon and the superficial flexor tendon. CONCLUSIONS: Intrathecal tenorrhaphy with external coaptation (in partial limb flexion) for 6 weeks resulted in gap healing, fibrous adhesion between the deep and superficial flexor tendons, fibrous tissue reduction of the intrathecal space, and a pasture-sound horse at 26 weeks. CLINICAL RELEVANCE: Without improved methods for immobilizing the deep digital flexor tendon, intrathecal tenorrhaphy is unlikely to result in first intention tendon healing.     

Tenectomy of the superficial digital flexor tendon as a treatment of suspected septic tendinitis and tenosynovitis of the digital flexor tendon sheath followed by rehabilitation with an orthotic device

A 15-year-old Sports horse gelding was referred for nonweightbearing lameness of the left hindlimb. Septic cellulitis was diagnosed and managed medically. After 14 days, septic tenosynovitis of the digital flexor tendon sheath (DFTS), with septic tendinitis of the superficial (SDFT) and deep (DDFT) digital flexor tendons, became evident. Surgical resection of the intrathecal portion of the septic SDFT was performed. Post-operatively, a half-limb cast was placed on the operated limb for 10 weeks followed by an articulated orthotic support boot during a rehabilitation period of 6 weeks. The horse recovered and regained long-term pasture soundness. Ultrasonography demonstrated the presence of bridging connective tissue in the location of the resected SDFT.     

Treatment and outcome of chronic septic tenosynovitis in three horses

Three horses were presented for treatment of chronic infections of the digital flexor tendon sheath. Clinical signs included severe lameness, and heat, pain and swelling of the digital flexor tendon sheath. The horses were treated with surgical lavage of the tendon sheath, systemic and local antibiotics, and analgesics. In each case, resolution of the lameness occurred over weeks to months. Only one horse returned to athletic activity, while the other two became comfortable at pasture. Response to treatment in cases of chronic tenosynovitis may not be as rapid or complete as that reported for acute tendon sheath infections.     

Septic tendonitis of the deep digital flexor tendon in a Thoroughbred horse referred for weight loss and intermittent fever

This case report describes the history, clinical and diagnostic findings, treatment and outcome of a 3‐year‐old Thoroughbred gelding. The horse was examined for chronic weight loss, intermittent fever of 4 months' duration and acute lameness of 2 weeks' duration, and was finally diagnosed with septic tendonitis of the deep digital flexor tendon and digital flexor tendon sheath caused by Streptococcus equi ssp. zooepidemicus. Investigation of the lower respiratory tract also allowed isolation of S. equi ssp. zooepidemicus. Although surgical treatment was recommended, because of the severity of the lesion and the guarded prognosis for a return to full athletic function, the owner declined surgery. The horse was therefore treated aggressively with antimicrobials using systemic, local and regional approaches, and with anti‐inflammatory drugs. At 20 months after discharge, the horse was able to race, and he is now in full work with 20 races finished successfully.     

Medical management of superficial digital flexor tendonitis: a comparative study in 219 horses (1992-2000)

REASONS FOR PERFORMING STUDY: There is a lack of long-term follow-up data for outcome of medical treatment of superficial digital flexor (SDF) tendonitis. OBJECTIVES: To determine whether intralesional injection of hyaluronan, beta aminoproprionitrile fumarate (BAPN) or polysulphated glycosaminoglycans (PSGAG) or systemic administration of PSGAG yielded better results than a controlled exercise programme alone in the management of SDF tendonitis, with a minimum follow-up period of 2 years after resumption of full work; and to determine whether reinjury rate was related to sports discipline and whether fibre alignment score (FAS) at 4 months could predict outcome. METHODS: In Study 1, 50 horses were managed by controlled exercise alone (Group A), 50 were treated with intralesional injection of hyaluronan (Group B), 20 received intralesional and systemic treatment with PSGAG (Group Ci) and 30 received systemic treatment with PSGAG (Group Cii). Horses in Groups B, Ci and Cii followed the same controlled exercise programme as Group A. In Study 2, 69 horses (Group D) were treated by intralesional injection of BAPN and followed a modified controlled exercise programme. Horses were re-examined clinically and ultrasonographically at intervals. Follow-up data were obtained for horses 2 years after resuming full work and for up to 6 years. RESULTS: There was no significant difference in reinjury rate of the treated limb(s) between Groups A, B, Ci and Cii (42.5-44.4%) (P>0.9). The reinjury rate (16%) in the treated limb(s) in Group D was significantly lower than in the other groups (P<0.001). However, when injury rate of the uninjured limb was considered, the results were similar to Study 1. In Study 2, the FAS at 4 months after treatment was a good predictor of outcome (P<0.001). Reinjury rates for different disciplines were similar in the 2 studies, with the risk of reinjury ascending from showjumpers to event horses to National Hunt and flat racehorses. CONCLUSIONS: Treatment with BAPN reduced the risk of reinjury in the treated limb, although the overall rate of subsequent injury was not affected. FAS at 4 months after treatment is a good predictor of outcome in the treated limb(s). POTENTIAL RELEVANCE: This study provides long-term follow-up data in horses from a variety of sports disciplines that can be used to provide prognostic information.     

Open drainage, intra-articular and systemic antibiotics in the treatment of septic arthritis/tenosynovitis in horses.

Open drainage was used to treat 26 horses with persistent or severe septic arthritis/tenosynovitis. Infected synovial structures were drained through a small (3 cm) arthrotomy incision that was left open and protected by a sterile bandage. Joint lavage was performed in all 26 horses. In addition to systemic antibiotics, 23 of these horses were also treated with intra-articular antibiotics; amikacin (17 horses), gentamycin (2 horses), cefazolin (2 horses), and 2 horses were injected at different times with gentamycin and amikacin. The infection was eliminated from the involved synovial structures in 25 of 26 horses; 24 survived and were released from the hospital. The arthrotomy incisions healed by granulation in 16 horses; in 9 horses the arthrotomy incision was sutured closed once the infection was eliminated. Seventeen horses returned to soundness and resumed athletic function. Open drainage was an effective method of achieving chronic drainage from a joint or tendon sheath. It is indicated in horses that have established intra-synovial infections or in horses that do not respond to joint lavage through needles.     

A collagenase gel/physical defect model for controlled induction of superficial digital flexor tendonitis

Reasons for performing study: A consistent and clinically relevant model for the induction of core lesions confined to the mid‐metacarpal superficial digital flexor tendon (SDFT) has not been previously reported. Injection of bacterial collagenase is commonly used but often results in large, irregular and inconsistent lesions that disrupt the superficial tendon layers and epitenon. Objective: To develop and evaluate a new injection technique for collagenase induction of SDFT injury. Methods: Collagenase gel was injected into a physical columnar defect created by longitudinally placing a curved 16 gauge 8.89 cm needle in the mid‐metacarpal SDFT in a randomly selected forelimb of 10 horses. A placebo treatment injection was performed 1 week later. Serial ultrasound examinations were performed. Horses were subjected to euthanasia at 2 (n = 2), 4 (n = 2), 8 (n = 4) and 16 (n = 2) weeks post treatment injection. Post mortem magnetic resonance imaging and histological analysis were performed. Gene expression (18S, SCX, TNC, TNMD, COL1A1, COL3A1, COMP, DCN, MMP1, MMP3 and MMP13), total DNA, glycosaminoglycan and collagen content were determined for experimental tendons (n = 10) and unaffected tendons (n = 9). Results: Mid‐metacarpal SDFT core lesion induction was successful in all tendons with consistent lesion cross‐sectional area and minimal epitenon disruption. Histology confirmed loss of normal tendon architecture after tendonitis induction and subsequent healing of the tendon core lesion. Compared with gene expression in unaffected tendons, several tested genes were significantly upregulated (COL1A1, COL3A1, TNMD, SCX, TNC, MMP13), while others showed significant downregulation (COMP, DCN, and MMP3). Conclusion: Compared with the previously used direct injection of collagenase, this injection technique was easily performed and induced more consistent lesions that were mid‐metacarpal and did not disrupt the epitenon. Potential relevance: This model will allow for objective assessment of therapies for tendon regeneration in the mid‐metacarpal SDFT prior to clinical trials and routine clinical application.     

Use of a bioabsorbable implant for the repair of severed digital flexor tendons in four horses

A new bioabsorbable implant composed of poly-L-lactic acid was used to repair the severed digital flexor tendons of four horses. The limbs were immobilised with distal casts which were changed after six to eight weeks and removed after 12 to 16 weeks. The horses were followed clinically and ultrasonographically for from seven to 19 months after the surgery. The ultrasonographic examination after the cast had been removed showed that the implants had been well incorporated into scar tissue. Two of the horses were mildly lame at the trot seven months after the surgery, but had returned to work after 12 months. The other two horses are still lame. No complications were observed with the implant.     

Desmotomy of the accessory ligament of the deep digital flexor tendon for treatment of chronic deep digital flexor tendinopathy in three Quarter Horses

Effective treatments for horses diagnosed with severe deep digital flexor (DDF) tendinopathy are limited. In this study, three Quarter Horses diagnosed with severe bilateral DDF tendinopathy underwent bilateral desmotomy of the accessory ligament of the DDF tendon after failing to respond to conservative therapy. Lameness markedly improved in all three horses. Given that severe DDF tendinopathy is typically associated with persistent or recurrent lameness, desmotomy of the accessory ligament of the DDF tendon might be a treatment option to alleviate lameness in horses with DDF tendinopathy. This treatment option appears promising; however, a larger number of cases is necessary to support the results in these three horses.     

Aseptic tenosynovitis of the carpal flexor sheath caused by rupture of the accessory ligament of the deep digital flexor tendon

A mare was evaluated for acute left forelimb lameness with effusion of the carpal flexor sheath. No osseous abnormalities were noted during radiographic examination. Significant disruption of the accessory ligament of the deep digital flexor tendon was seen during ultrasonographic examination. Carpal sheath effusion and lameness resolved after medical treatment.     

A retrospective study of 192 horses affected with septic arthritis/tenosynovitis.

The medical records of 192 horses with septic arthritis/tenosynovitis 1979-1989 were reviewed. Forty-three horses developed infection after an intra-articular injection, 46 following a penetrating wound, 25 following surgery, 66 were foals less than 6 months old, and 12 were adult horses without a known aetiology. Haematogenous infection of a joint occurs in adult horses and should be considered as a differential diagnosis in horses with an acute onset of severe lameness. The aetiology of the infection had a significant effect on the type of bacteria identified by culture. Staphylococcus was cultured from most of the horses that developed infection following a joint injection or surgery, 69% of the horses from which an organism was identified. Horses that developed infection secondary to a penetrating wound frequently provided cultures of more than one organism; Enterobacteriaceae and anaerobes were more frequently isolated in this group. The most common organisms isolated from foals were Enterobacteriaceae; E. coli was identified in more than 27% of the foals. The hock was the most frequently involved joint. Multiple treatments were used over the 10-year period of study. Survival rates were lowest in foals; only 45% survived to be released from the hospital. Survival was greater in adult horses; 85% of the horses that were treated were released from the hospital. Survival was significantly greater in horses with septic tenosynovitis; all 14 of the horses that were treated survived. Survival was not significantly affected by the joint involved or by the type of bacteria cultured from the synovial fluid.(ABSTRACT TRUNCATED AT 250 WORDS)     

Tenoscopy in 33 horses with septic and nonseptic digital tenosynovitis (1997–2001)

Tenoscopy is the use of an arthroscope to access tendon sheaths. This article reports clinical findings, treatments, and outcomes of 33 horses with either septic or nonseptic digital tenosynovitis submitted to 36 tenoscopies during 34 occasions at the Marion duPont Scott Equine Medical Center (1997–2001). Two of the 16 horses with septic tenosynovitis were euthanized at the hospital. From the 32 horses discharged from the hospital, outcome was obtained in 31 cases: 12 horses (6 septic) could work at the same level. No difference was detected between the outcome groups regarding clinical and laboratory variables. In nonseptic cases, lameness grade, circulating white blood cells, and plasma fibrinogen before surgery were lower, while the period between the onset of clinical signs and surgery was longer and duration of phenylbutazone treatment and hospitalization was shorter. No difference in the outcome was detected when septic and nonseptic cases were compared. Tenoscopy was useful for diagnosis and treatment of nonseptic and septic digital tenosynovitis. The small number of cases and the lack of accurate information due to the retrospective nature of the study may have prevented detection of a difference between the outcomes of horses with septic versus nonseptic tenosynovitis.