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.     

PREVALENCE OF COMPUTED TOMOGRAPHIC SUBCHONDRAL BONE LESIONS IN THE SCAPULOHUMERAL JOINT OF 32 IMMATURE DOGS WITH THORACIC LIMB LAMENESS

Osteochondrosis is a common developmental abnormality affecting the subchondral bone of immature, large breed dogs. The purpose of this retrospective study was to describe CT lesions detected in scapulohumeral joints of 32 immature dogs undergoing CT for thoracic limb lameness. Eight dogs (14 scapulohumeral joints) had arthroscopy following imaging. Thirteen dogs (19 scapulohumeral joints) were found to have CT lesions, including 10 dogs (16 scapulohumeral joints) with subchondral bone lesions and 3 dogs with enthesopathy of the supraspinatus tendon. In one dog, subchondral bone lesions appeared as large oval defects within the mid‐aspect of the glenoid cavities, bilaterally. These lesions resembled osseous cyst‐like lesions commonly identified in the horse. This is the first report of such a presentation of a subchondral bone lesion in the glenoid cavity of a dog. In all dogs, small, focal, round or linear lucent defects were visible within the cortical bone at the junction of the greater tubercle and intertubercular groove. These structures were thought to represent vascular channels. Findings from this study support the use of CT as an adjunct modality for the identification and characterization of scapulohumeral subchondral bone lesions in immature dogs with thoracic limb lameness.     

Can distal border fragments of the navicular bone be a primary cause of lameness?

A horse with unilateral forelimb lameness and pain localised to the palmar aspect of the foot was evaluated using radiography and low field magnetic resonance (MR) imaging. A distal border fragment of the navicular bone, an osseous cyst‐like lesion (OCLL) in the distal third of the navicular bone and focal distal sesamoidean impar desmitis were identified as the most likely causes of pain and lameness. No other lesions likely to contribute to pain and lameness were identified on MR images or gross post mortem examination. The OCLL was characterised histologically by enlarged bone lacunae containing proliferative fibrovascular tissue. Focal lesions of the distal aspect of the navicular bone are rarely found in isolation but can be causes of pain and lameness in horses.     

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.     

Evaluation of a technique for collection of cancellous bone graft from the proximal humerus in horses

OBJECTIVES: To describe a technique for collecting cancellous bone graft from the proximal humerus in horses. STUDY DESIGN: Prospective evaluation of an experimental bone graft collection technique. ANIMAL POPULATION: Eight horses, 3-15 years, weighing 495-605 kg. METHODS: Horses were anesthetized and positioned in lateral recumbency. The lateral aspect of the proximal humerus was exposed by a 7-10-cm incision extending distally from the greater humeral tubercle, followed by sharp dissection through the omotransversarius muscle and between the infraspinatus and deltoideus muscles. A 12-mm cortical defect was incrementally created in the lateral proximal humerus. Human bone graft harvesting equipment (Acumed, Beaverton, OR) was drilled through this defect to collect a core of cancellous bone. In five horses additional cancellous bone was then collected with conventional instruments. Bone samples were weighed and histologically examined. Horses were monitored and graded for quality of anesthetic recovery, incisional complications, and postoperative lameness. RESULTS: Total mean (+/-SD) surgical time for harvesting bone with the Acumed system and traditional techniques (n=5) was 38+/-6 minutes (range, 32-47 minutes). Mean cancellous bone weight collected with the Acumed system was 3.6+/-0.8 g (range, 2.0-4.6 g), and cancellous bone collected conventionally was 25.6+/-7.5 g (range, 16.8-34.2 g). Minimal incisional complications or postoperative lameness were observed. Mortality was 12.5%; one horse fractured the operated humerus during anesthetic recovery. CONCLUSION: The Acumed system provided limited cancellous bone when used with the technique described. However, the quantity of cancellous bone collected with traditional harvesting instruments was comparable to other sites used in horses. The procedure was associated with minimal postoperative incisional complications or lameness, but because one horse suffered a catastrophic humeral fracture further research is required to assess the effects of this procedure on humeral breaking strength. CLINICAL RELEVANCE: Based on the risk of catastrophic fracture, this technique cannot be recommended for use in clinical cases, especially if an unassisted recovery from general anesthesia is planned.     

Case Report of a Complex Lateral Femorotibial Joint Injury With Popliteal Tendonitis in a Foal

A two-month-old, Spanish breed, foal was referred with right hind limb lameness of two weeks duration. Clinical examinations confirmed a complex combination of lesions within the lateral femorotibial joint, including a subchondral bone cyst in the lateral femoral condyle, a severe popliteal tendonitis, and a delayed cartilage detachment of the lateral femoral condyle. Because of the complex association of these lesions, poor prognosis for an athletic career was given to the owner. Four years later, the filly is pasture sound. Lesions of the popliteal tendon in the horse are uncommon. The popliteal tendon should also be investigated in cases of trauma to the lateral femorotibial joint, as it could be associated with other affected structures.     

Arthroscopic autologous osteochondral mosaicplasty for the treatment of subchondral cystic lesion in the medial femoral condyle in a horse

An 11-year-old, Hungarian half-bred stallion was presented with a history of mixed left hindlimb lameness of 6 months duration. Subchondral bone cyst of the medial femoral condyle and injury of the medial meniscus were diagnosed. Osteochondral autograft transplantation (mosaic arthroplasty) was performed, taking grafts from the less weight-bearing medial border of the medial femoral trochlea of the affected limb, and transplanting them into the cyst during arthroscopy. The lameness was evaluated prior to and one year after the operation with a motion analysis system during treadmill exercise. Considerable improvement of the lameness and the clinical signs as well as successful transplantation of the grafts, and a new hard joint cartilage surface of the medial femoral condyle could be detected during follow-up arthroscopy. Osteochondral autograft transplantation seems to bee a possible alternative for treating subchondral cystic lesions of the medial femoral condyle in horses. A new technique for the surgical treatment of a subchondral cystic lesion of the medial femoral condyle in the horse is described.     

CLINICAL AND DIAGNOSTIC IMAGING FINDINGS IN HORSES WITH SUBCHONDRAL BONE TRAUMA OF THE SAGITTAL GROOVE OF THE PROXIMAL PHALANX

Eight sports horses with unilateral (4) or bilateral (3) forelimb or unilateral hindlimb (1) lameness had subtle radiologic abnormalities of the subchondral bone of the sagittal groove of the proximal phalanx associated with moderate or intense increased radiopharmaceutical uptake. High‐field or low‐field magnetic resonance (MR) imaging confirmed the presence of a fissure fracture or subchondral and trabecular bone trauma. Seven of eight lesions were located approximately midway between the dorsal and palmar cortices of the proximal phalanx; the eighth was sited more dorsally. Two horses underwent follow‐up MR imaging and abnormal signal intensity persisted, with little change.     

Bilateral hypoplasia of the minor tubercle of the humerus with medial luxation of the biceps tendon in two Quarter Horses

Two Quarter Horses were examined at the Washington State University Veterinary Teaching Hospital with forelimb lameness. Case 1 was a 4‐year‐old female with a 4 month history of intermittent forelimb lameness that had partially responded to oral anti‐inflammatories. The horse was in full training and actively competing in cutting. Case 2 was a one‐year‐old filly bred for cutting that presented with a right forelimb lameness of 3 weeks’ duration, which was not responsive to oral anti‐inflammatories. The horse was not in training. On lameness examination, Case 1 was grade 1/5 (American Association of Equine Practitioners scale) lame in the left forelimb in a straight line on a hard surface, extension and flexion of the shoulder was resented and exacerbated the lameness. Case 2 was grade 3/5 lame in the right forelimb in a straight line on a hard surface, flexion and extension of the shoulder was resented and exacerbated the lameness. Both horses had a characteristic dished appearance to the dorsal aspect of the shoulder, with prominence of the proximal aspect of the humerus. Ultrasound and proximodistal oblique (skyline) radiographic views of the scapulohumeral joints demonstrated bilateral hypoplasia of the minor tubercle of the humerus with bilateral medial luxation of the proximal biceps tendon in both cases. To the authors' knowledge this is the first report of 2 cases of bilaterally affected horses, as well as the first report of the condition in the Quarter Horse breed.     

Use of magnetic resonance imaging for identifying subchondral bone damage in horses: 11 cases (1999-2003)

OBJECTIVE: To assess the use of magnetic resonance (MR) imaging for identifying subchondral bone damage in the distal limbs of horses. DESIGN: Retrospective study. ANIMALS: 11 horses. PROCEDURE: Medical records of horses with lameness and subsequent evidence of subchondral bone damage as determined by MR imaging were reviewed. Severity and duration of lameness, results of diagnostic local anesthesia and diagnostic testing, surgical and necropsy findings, and treatment were recorded. Outcome was determined by follow-up information obtained from the owner or referring veterinarian. RESULTS: Lameness was localized by physical examination and diagnostic local anesthesia. Lameness was localized to the metacarpophalangeal or metatarsophalangeal joint in 4 horses, distal interphalangeal joint in 5 horses, and tarsocrural joint in 2 horses. The duration of lameness ranged from 2 weeks to 20 months. Magnetic resonance imaging of the affected joints revealed abnormal fluid accumulation within the subchondral bone. None of the abnormalities observed by MR imaging were detected by radiography. Subchondral bone damage was diagnosed in all horses. Arthroscopy of the affected joint was performed in 4 horses. Communication with the articular surface of the affected bone was suspected on the basis of results of MR imaging in 4 horses and was confirmed by arthroscopy in 1 horse and by necropsy in 1 horse. CONCLUSIONS AND CLINICAL RELEVANCE: Magnetic resonance imaging was useful for providing a diagnosis when other imaging techniques did not definitively identify the cause of lameness. Subchondral bone damage was clearly identified by MR imaging and should be considered as a cause of lameness in horses in which radiographic findings are unremarkable.     

Tiludronate infusion in the treatment of bone spavin: A double blind placebo‐controlled trial

Reasons for performing study: Tiludronate regulates bone remodelling through a decrease of the resorptive process and should therefore ameliorate the remodelling processes active in osteoarthritis of the distal tarsal joints (‘bone spavin’) and alleviate pain associated with abnormal bone lysis. Objective: To confirm the efficacy of tiludronate, administered as a single infusion at a dose of 1 mg/kg bwt, in the treatment of bone spavin in the horse. Methods: A double blind placebo controlled trial on 108 clinical cases of bone spavin was undertaken. The lameness score of the lamest limb was assessed following distal tarsal analgesia of the contralateral limb and followed‐up using the same procedure throughout the study. Bone spavin in the lamest limb was confirmed by distal tarsal analgesia and radiography. Horses were treated at Day 0 and reassessed 60 days later after controlled exercise. A second nonblinded treatment was given to unresponsive horses and all horses were re‐examined at Day 120. Exercise levels were recorded at each examination. Results: Eighty‐seven horses completed the trial as per the protocol. The tiludronate horses were significantly less lame than the placebo horses (P = 0.0318). Horses treated at Day 60 with tiludronate showed further improvement in lameness at Day 120 (P = 0.0096 and P = 0.0034 for horses treated with tiludronate and placebo at Day 0, respectively). The only significant difference in radiographic findings between tiludronate and placebo was for presence of periarticular osteophytes (P = 0.006). Conclusions: Tiludronate treatment is proven to be effective in bone spavin in horses in association with a controlled exercise programme. Clinical relevance: Tiludronate in combination with controlled exercise offers an alternate medical treatment for bone spavin.     

Autologous osteochondral grafting (mosaic arthroplasty) for treatment of subchondral cystic lesions in the equine stifle and fetlock joints

OBJECTIVE: To describe treatment of equine subchondral bone cysts (SBCs) by reconstruction of the articular surface with osteochondral grafts. STUDY DESIGN: Case series of horses with SBCs unresponsive to conservative therapy. ANIMALS: Eleven horses (1-12 years). METHODS: SBCs were identified in 4 locations: medial femoral condyle (5 horses), lateral femoral condyle (1), distal epiphysis of the metacarpus (4), or metatarsus (1). Osteochondral autograft transplantation (mosaic arthroplasty) was performed, taking grafts from the abaxial border of the medial femoral trochlea of the unaffected limb. Graft implantation was achieved through a small arthrotomy or by arthroscopy depending on SBC location. RESULTS: All horses improved postoperatively; 10 horses had successful outcomes with radiographic evidence of successful graft incorporation and 7 returned to a previous or higher activity level. On follow-up arthroscopy (5 horses) there was successful reconstitution of a functional gliding surface. One horse had delayed incorporation of a graft because of a technical error but became sound. One horse had recurrence after 4 years of work and soundness. One stallion was used for breeding and light riding because of medial meniscal injuries on the same limb. CONCLUSIONS: Implantation of osteochondral grafts should be considered for SBC when conservative management has not improved lameness and there is a risk of further joint injury and degeneration. CLINICAL RELEVANCE: Mosaic arthroplasty should be considered for treatment of subchondral bone cysts of the femoral condyle and distal articular surface of the metacarpus/tarsus in horses that are refractory to non-surgical management.     

Ultrasonographic examination of the proximal tendon of the biceps brachii: Technique and reference images

Ultrasonography of the shoulder is of interest in the diagnosis of proximal forelimb lameness. The proximal tendon of the biceps brachii (PTBB) and its associated structures are frequently injured and should be included in the routine ultrasonographic examination of the shoulder. This paper describes a complete ultrasonographic procedure for examining the bicipital apparatus, on transverse and longitudinal scans, from the insertion of the PTBB on the supraglenoid tubercle to the muscle body below the intertubercular sulcus.     

Proximal interphalangeal joint arthrodesis in 34 horses using two parallel 5.5-mm cortical bone screws

OBJECTIVE: To report clinical experience with arthrodesis of the proximal interphalangeal joint in horses using two parallel 5.5-mm cortical bone screws placed in lag fashion. STUDY DESIGN: Retrospective, clinical study. ANIMALS: Thirty-four horses, aged 1 to 19 years. METHODS: Medical records for all horses admitted (1991-1997) for pastern arthrodesis using two 5.5-mm ASIF cortical bone screws, in parallel orientation, and placed in lag fashion by use of a combined aiming device to facilitate accuracy were reviewed. Signalment, lameness diagnosis, duration of lameness, limb(s) involved, and outcome were recorded. Criteria for successful outcome were determined as return to previous level of function or future intended athletic use. RESULTS: Thirty-nine proximal interphalangeal joint arthrodeses were performed on 34 horses. One horse was euthanatized in the recovery room and was excluded from data analysis. Successful outcome occurred in 85% of frontlimbs and 89% of hindlimbs. Failure occurred in 5 joints; 1 horse had lameness directly associated with surgery, whereas 4 horses had unrelated lameness. CONCLUSION AND CLINICAL RELEVANCE: Age, breed, and initial disease did not affect outcome. Arthrodesis of the proximal interphalangeal joint by use of two 5.5-mm ASIF cortical bone screws, in parallel orientation, placed in lag fashion by use of a combined aiming device, resulted in sound use of the limb in >85% of the joints with shortened postoperative coaptation.     

Anatomische und röntgenologische Untersuchungen am Schultergelenk des Geparden (Acinonyx jubatus)

Anatomical structures of shoulder joints of five adult cheetahs were examined by dissection, corrosion casts and radiography. The bones, capsules and auxiliary synovial devices were described, as well as ligaments and adjacent muscles. The cheetah shoulder has many similarities with the shoulder joint of the domestic cat, but also considerable differences. Proper osteological features were the large supraglenoid tubercle, the caudally directed coracoid process and the extension of the articular surface of the scapula to the lateral area of the supraglenoid tubercle. On the proximal end of the humerus the width of the head of humerus, the facet of infraspinatus muscle as a shallow cavity with the insertion of the infraspinatus muscle around it and two raised roughnesses on the proximal end of the tricipital line for the insertions of the lateral glenohumeral ligament and the teres minor muscle were noticeable. The insertion of the joint capsule was mainly on the glenoid labrum, only in part of the articular surface on the lateral area of the supraglenoid tubercle laterally on the scapula. The joint capsule formed a supra- and infraspinatus recess laterally, an intertubercular tendon sheet for the biceps brachii muscle cranially, and a bipartited subscapular recess medially. An extracapsular transverse ligament passing the intertubercular groove, a laterally capsular strengthening—called lateral glenohumeral ligament—and an intracapsular medial glenohumeral ligament could be found. The latter one was joined to the capsule by a mesoligament, dividing the subscapular recess into two pouches.     

Placement of bone screws in a standing horse for treatment of a fracture of the greater tubercle of the humerus

A mature Thoroughbred gelding that was used as a high level jumper presented for evaluation of a nonweightbearing forelimb lameness following a fall. Radiographs revealed a complete, noncomminuted, minimally displaced sagittal fracture of the greater tubercle. Supporting limb laminitis was a major concern in the short term based on the severe lameness at presentation. Open reduction with internal fixation was chosen over stall rest in an attempt to more rapidly return the weightbearing function to the limb. The procedure was performed standing and 3 bone screws were placed standing in an attempt to avoid implant or catastrophic bone failure that can accompany recovery from general anaesthesia. The day following surgery the lameness was significantly improved as the horse was able to bear some weight on the heel. The gelding was discharged 5 days following surgery and was fully weightbearing at the walk. Six months following surgery the horse was free of lameness and resumed training. This report describes our experience and rationale in placing bone screws in a standing horse for treatment of a greater tubercle fracture.     

Arthroscopic treatment of meniscal cysts in the horse

Reasons for performing study: To describe the clinical symptoms, treatment, and outcome of meniscal cysts in horses. These structures have not been previously described in the literature as a potential cause of lameness in the horse. Hypothesis: Meniscal cysts are an uncommon condition of the femorotibial joint but can be a significant cause of lameness. Symptoms can be resolved by arthroscopic excision. Methods: Records of horses diagnosed with meniscal cysts and treated by cyst excision and meniscal debridement at 2 surgical practices were reviewed. Clinical outcome was determined by repeat veterinary examination and contact with owner. Results: Seven cases of meniscal cyst were treated with arthroscopic cyst excision and meniscal debridement. Five of 7 horses had lameness attributable to femorotibial joint pathology, while the remaining 2 horses had meniscal cysts found incidentally during diagnostic arthroscopy for the treatment of osteochondritis dissecans of the lateral trochlear ridge of the femur. Five of 6 horses with long‐term follow‐up were sound and a 7th horse was improved 11 months after surgery. Conclusions and potential relevance: Meniscal cysts, while uncommon, can be associated with progressive lameness in the horse. Surgical excision of the cysts results in resolution or improvement of symptoms, without evidence of recurrence on follow‐up examination.     

ULTRASONOGRAPHY OF THE EQUINE BICIPITAL TENDON REGION: A CASE HISTORY REPORT AND REVIEW OF ANATOMY

The equine shoulder region is difficult to investigate by conventional imaging modalities. Diagnostic ultrasound has proven valuable for investigation of soft tissue injuries of the human shoulder. In a horse with shoulder lameness, the authors employed diagnostic ultrasound to augment the use of conventional radiography. A defect in the subchondral bone layer of the medial humeral tuberosity, with adjacent bony fragments were clearly identified with ultrasound. Ultrasound was used for initial evaluation of the bicipital tendon and bursa. The technique was subsequently used to follow and evaluate the post-operative condition of the proximal cranial humerus, bicipital tendon and bursa in this patient. The bicipital regions of 2 immature and 3 adult normal horses were also examined with to illustrate the normal ultrasonographic anatomy of the cranial shoulder region.     

Osseous cyst‐like lesions/subchondral bone cysts of the phalanges

In the horse, the phalanges are the second most common location for the occurrence of osseous cyst‐like lesions (OCLLs) after the medial femoral condyle of the stifle. Phalangeal OCLLs occur in a variety of locations, most of which are adjacent to, if not communicating with, a joint. The aetiology of these lesions is considered to be multifactorial by most authors. Horses with OCLLs demonstrate lameness of varying severity. Diagnostic analgesia should be used to localise the lameness. After localisation of the lameness, standard radiographic views of the isolated area should be performed. The radiographic characteristics of OCLLs are dependent on the stage of development of the OCLL; OCLLs may first be identified as a small lucent flattening or depression in the articular surface; however, they may progress to a circular, oval or conical single or multi chambered radiolucency within the bone. There may be a rim of radiodense sclerosis around the lucency. Diagnosis of some OCLLs may only be achieved using nonstandard radiographic views or may require advanced diagnostic imaging modalities such as computed tomography or magnetic resonance imaging. Treatment of phalangeal cysts may be conservative or surgical. Surgical treatment options generally aim to prevent cyst enlargement and promote filling of the lesion with osseous material. Depending on the cyst, this can be performed arthroscopically or via an extra‐articular approach. Occasionally, the severity of proximal interphalangeal joint OCLLs warrants surgical arthrodesis. Overall the prognosis for return to performance for horses with OCLLs ranges from 30–90% but is dependent on the breed, age and intended use of the horse, surface area of weightbearing cartilage affected, concurrent osteoarthritis within the joint and treatment administered.     

Healing of full-thickness cartilage compared with full-thickness cartilage and subchondral bone defects in the equine third carpal bone.

The effect of lesion depth on the quality of third carpal bone cartilage repair was examined. A 1-cm diameter articular defect penetrating the calcified cartilage in one limb and the subchondral bone plate in the opposite limb was created in the radial facet of the third carpal bones. Clinical and xeroradiographic examinations were performed every 4 weeks until 4 months (3 horses) and 6 months (3 horses) after surgery. The synovial membrane, non-opposing articular surfaces and articular defects were examined grossly, histologically and histochemically. Grossly, deeper defects contained thicker, whiter tissue, but both joints contained generalised degenerative changes. Defects extending through calcified cartilage were filled deeply by fibrocartilage and superficially by fibrous connective tissue. Defects extending through subchondral bone were consistently filled with hyaline-like cartilage in the depths of the lesion, fibrocartilage in the intermediate layer and fibrous connective tissue superficially. The results indicate that subchondral bone is the source of hyaline-like cartilage repair tissue and suggest that quality of healing of cartilage defects may be improved by penetrating the subchondral bone plate. It also appears that the synovitis associated with the procedure must be controlled before the procedure can be advocated for treatment of clinical cases.