74 EQUINE VETERINARY EDUCATION / AE / March 2007 Case Report Mineralisation of the biceps brachii tendon in a 6-year-old Cob mare S. J. BOYS SMITH† AND E. R. SINGER* Philip Leverhulme Large Animal Hospital, Leahurst, University of Liverpool, Chester High Road, Neston, Cheshire CH64 7TE, UK. Keywords: horse; biceps brachii tendon; mineralisation; calcification Introduction Diagnostic techniques: The lameness did not change following regional analgesia using 2% mepivicaine Mineralisation of the biceps brachii tendon is an uncommon hydrochloride (Intra-Epicaine)1 of the palmar digital nerves, condition in horses (Adams and Blevins 1989a) and may be palmar nerves at the level of the proximal sesamoid bones, associated with bicipital bursitis and osseous pathology palmar and palmar metacarpal nerves at the level of the distal (Fugaro and Adams 2002). Calcifying tendonopathy has been metacarpus, palmar metacarpal nerves at the level of the reported previously in dogs and man (Muir et al. 1992). proximal metacarpus and the median and ulnar nerves; or This case report describes the presentation, following intrasynovial anaesthesia of the middle carpal, diagnosis and pathological findings in a mare with antebrachiocarpal, elbow and shoulder joints and mineralisation of the biceps brachii tendon. These intertubercular bursa (Bassage and Ross 2003). findings demonstrate advanced pathology despite mild Nuclear scintigraphy was performed 2 weeks following clinical signs on initial presentation. diagnostic analgesia as a result of the negative findings. On re-examination, the lameness had deteriorated by one grade. Case details The mare was given 10 MBq/kg bwt i.v. 99mtechnetium methylene-diphosphonate (99Tc-MDP)2 through a 14 gauge History catheter (Intraflon 2)3. Bone phase images were obtained of the forelimbs and cervical spine 3 h after injection of the A 6-year-old Cob mare was presented to the Philip Leverhulme radiopharmaceutical. Images were analysed using Hermes Large Animal Hospital with a right forelimb lameness of software (Nuclear Diagnostics)4. When compared to the left 3 months’ duration. The lameness, insidious in onset, was limb there was 50% increased radiopharmaceutical uptake gradually deteriorating and had not improved following rest or (IRU) in the region of the right humeral tubercles and a 56% nonsteroidal anti-inflammatory medication. IRU in the region of the right supraglenoid tubercle of the scapula (Fig 1). Clinical findings Mediolateral (Fig 2), craniomedial-caudolateral oblique radiographs of the right shoulder joint and cranioproximal- There was mild atrophy of the right supraspinatous and craniodistal oblique radiographs of the right humeral infraspinatous muscles. Biceps brachii tendon palpation, limb tubercles were obtained. Mediolateral radiographs of the protraction and retraction were not resented. The heels of the left shoulder were taken for comparison (Butler et al. 2000) right fore foot were overgrown and contracted. The mare was using a Polydorus 80 X-ray unit (Siemens)5. There were 1/10 right fore lame at the walk with a decreased cranial 3 areas of discrete irregular radiopacity within the soft tissue phase of the stride, a reduced height of foot flight and landing structures, consistent with mineralisation, on the cranial toe first. The mare was 3/10 right fore lame at the trot (Ross aspect of the shoulder joint. These areas were immediately 2003) and on the lunge, regardless of direction. Flexion tests cranial to the supraglenoid tubercle, cranioproximal to the were negative. humeral tubercles and just proximal to the deltoid tuberosity. The findings were consistent with mineralisation of the biceps brachii tendon. The supraglenoid and humeral tubercles were enlarged, irregular in outline and sclerotic. *Author to whom correspondence should be addressed. †Present address: Rossdale and Partners, Rossdale Equine Hospital, Cotton End There was an irregular radiolucent line present in the Road, Exning, Newmarket, Suffolk CB8 7NN, UK. supraglenoid tubercle extending proximally from the distal EQUINE VETERINARY EDUCATION / AE / March 2007 75 aspect of the tubercle. These findings are consistent with Discussion advanced modelling changes of the supraglenoid tubercle and humeral tubercles. The presence of an old healed In the normal horse, the biceps brachii tendon originates from fracture of the supraglenoid tubercle could not be the supraglenoid tubercle and inserts on the radial tuberosity, excluded. medial collateral ligament of the elbow joint, the antebrachial Ultrasonographic examination (Reef 1998) using a fascia and the extensor carpi radialis tendon. The biceps 5–10 MHz linear array transducer (Diasus)6 showed a marked brachii tendon is bilobed, positioned between the greater and increase in echogenicity of the cranial aspect of both the lesser humeral tubercles. It runs over the intermediate tubercle lateral and medial lobes of the right biceps brachii tendon as and sulcus intertubercularis where it is predominantly compared to the left. Acoustic shadows were present, fibrocartilaginous in this region (Meagher 1979). The tendon consistent with mineralisation of the tendon. No normal continues as the biceps brachii muscle at the tendon tissue was visualised. There was no bursal distension. musculotendonous junction, which lies distal to the humeral The left tendon and humeral tubercles appeared normal tubercles (Crabill et al. 1995). (Fig 3). Mineralisation commonly affects fibrocartilage or occurs at the musculotendonous junction in man (Muir et al. 1992; Diagnosis Doherty 1994). Due to anatomical location, the tendon is predisposed to trauma in horses (Fugaro and Adams 2002). A diagnosis of extensive mineralisation of the biceps brachii The combination of location and its fibrocartilaginous tendon was made. There was also severe modelling of the structure may explain why mineralisation of the biceps brachii supraglenoid and humeral tubercles. tendon has been more frequently reported than mineralisation of other tendons. Treatment This mare demonstrated many of the signs associated with biceps brachii mineralisation, biceps tendinitis or bicipital Conservative management of this case had been unsuccessful bursitis. These included lameness with a reduced cranial phase with continued clinical deterioration. In view of the advanced of the stride and height of foot flight, toe-heel landing with changes present, the outcome following surgical treatment the heels being overgrown and contracted and shoulder (removal of the mineralised section of the tendon or complete muscle atrophy (Meagher 1979; Dyson 1985; Pankowski transection of the biceps brachii tendon) could not be 1986; Gillis and Vatistas 1997). In contrast to previous reports, guaranteed. The owners elected for euthanasia. this mare did not show pain on tendon palpation or flexion and extension of the shoulder joint. There was no localised Gross pathological findings heat or swelling (Meagher 1979; Adams and Blevins 1989b). Three equine cases of combined bicipital bursitis, tendonitis The right biceps brachii tendon was moderately enlarged. and humeral osteitis presented with a dropped elbow and Extensive ossification of the tendon was present extending partially flexed carpal and fetlock joints, thought to be due to from the tendon origin to the musculotendonous junction. pain associated with the use of the passive-stay apparatus This ossification had the appearance of cortical bone, as the (Fugaro and Adams 2002). These clinical signs were not outer surface was smooth in outline and the inside was dense evident in this mare despite the significant tendon and not composed of trabecular bone. The caudal aspect of mineralisation, bursitis and osseous modelling. the tendon was very roughened and fibrous. Numerous Some cases of bicipital bursitis are responsive to intrathecal adhesions of fibrous tissue connected the tendon to the anaesthesia of the intertubercular bursa (Meagher 1979); humerus. The humeral tubercles, particularly the lateral however, a negative response to local anaesthesia should be tubercle, were enlarged and misshapen. The fibrocartilage of interpreted with caution (Dyson and Dik 1995). Intrathecal the humeral tubercles was discoloured and of variable anaesthesia is difficult, synovial fluid is not always obtained, thickness with numerous fissures and erosions. The right anaesthesia can take up to 1 h to have effect and large supraglenoid tubercle was grossly enlarged and irregular. volumes of anaesthetic can easily be injected outside the Grossly, the synovial fluid from the intertubercular bursa had synovial cavity (Dyson 1986a,b). Thus, negative results (as in decreased viscosity while synovial fluid from the shoulder joint this case) do not rule out pain originating from this area. In appeared normal (Fig 4). this case local analgesia was useful in eliminating the distal limb as a cause of lameness. Histopathological findings: Histopathology of the left and Lameness associated with the biceps brachii tendon may right biceps brachii tendons was performed. Demineralisation have both pain and mechanical components. Pain is probably of the right tendon was necessary prior to staining with due to inflammation, adhesions and new bone formation in haematoxylin and eosin7. The affected tendon was composed the intertubercular groove or the movement of the tendon entirely of compact bone (Fig 5). A few medullary cavities within the inflamed bursa overlying the humeral tubercles containing fat, blood cells and bone marrow