74 EQUINE VETERINARY EDUCATION / AE / March 2007

Case Report Mineralisation of the 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: ; 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 (Adams and Blevins 1989a) and may be palmar nerves at the level of the proximal sesamoid , 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, 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. 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 of the (Fig 1). Clinical findings Mediolateral (Fig 2), craniomedial-caudolateral oblique radiographs of the right 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 , cranioproximal to the were negative. humeral tubercles and just proximal to the . 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 , 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); . 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 cells were (Uhthoff et al. 1976; Lincoln and Potter 1984; Fossum et al. present. No normal tendonous tissue remained. The left 1997). Following mineralisation, a resorptive phase occurs tendon was normal. which has been associated with pain in human beings 76 EQUINE VETERINARY EDUCATION / AE / March 2007

a) b) (Uhthoff et al. 1976). An influx of phagocytic cells and vascular structures is thought to increase intertendonous  pressures causing pain (Re and Karzel 1993). No histological signs of resorption were evident in this case. A mechanical  lameness due to adhesions between the tendon, bone and bursa, decreased elasticity of the tendon or an alteration in the tendon size and shape would lead to restricted movement (Fossum et al. 1997; Adams and Turner 1999; Fugaro and Cranial Cranial Adams 2002). A mechanical lameness would not respond to local analgesia. Fig 1: Lateral scintigraphic images of the left (a) and right (b) The extent of the mineralisation within the biceps brachii shoulder region. There is normal distribution of the tendon is often not consistent with the interval between onset radionucleotide uptake in the left shoulder. Compared to the left shoulder, there is a 50% increase in radiopharmaceutical of lameness and radiography (Dyson 1985). The advanced uptake (RU) on the cranioproximal aspect of the right humerus state of the radiographical and pathological changes in this (red arrow) in the region of the humeral tubercles and the case was not consistent with the 3 month history of lameness. biceps brachii tendon; and a 56% increase in Tendon mineralisation has been discovered as incidental radiopharmaceutical uptake in the region of the right findings in man and dogs (Flo and Middleton 1990; Faure and supraglenoid tuberosity (white arrow). Dieppe 1994; Kramer et al. 2001). Lameness may develop only after a certain level of pathology has developed. The aetiology of tendon mineralisation is not known. The terms used to describe the change of soft tissue into mineral or bone are explained in Table 1. Dystrophic, developmental and metastatic causes of mineralisation have been suggested. Dystrophic mineralisation occurs secondarily to trauma and may ultimately become ossified (Dyson 2003), as in this case. Anatomically the biceps brachii tendon is highly susceptible to trauma (Muir et al. 1992) and is the most likely aetiology in this mare. A developmental anomaly of bilateral biceps brachii tendon mineralisation has been reported in a 4-year-old

 Quarter Horse, where the fibrocartilage within the tendon was  suspected to have undergone endochondral ossification

a) b)





 Cranial

Fig 2: Mediolateral radiograph of the right shoulder taken with a low exposure to highlight the soft tissue structures on the Lateral Lateral cranial aspect of the shoulder. There are 3 discrete areas of increased, irregular radiopacity within the soft tissue that are Fig 3: (a) Ultrasonographic image of the left (normal) lateral consistent with mineralisation. These areas are marked by lobe of the biceps brachii tendon just distal to the proximal arrows and are immediately cranial to the supraglenoid aspect of the humerus. The tendon is of normal appearance, tuberosity, cranioproximal to the humeral tubercles and just size and structure. The underlying humerus is smooth in outline proximal to the deltoid tuberosity (arrows). The humeral and can be visualised easily. There is no effusion of the lateral tubercles (cranial eminence of the and recess of the intertubercular bursa. (b) Ultrasonographic image intermediate tubercle) are enlarged, irregular in outline and of the right (abnormal) lateral lobe of the biceps brachii tendon sclerotic. Inset: Detail of the supraglenoid tubercle taken with a just distal to the proximal aspect of the humerus. There is higher exposure. It is enlarged and irregular in outline. The hyperechogenic material, consistent with mineralisation, on pattern of increased radiopharmaceutical uptake that is the cranial aspect of the tendon (red arrow) casting an acoustic demonstrated in Figure 1b is very similar to the areas of shadow (white arrow) that prevents visualisation of the cranial mineralisation seen radiographically. humerus. EQUINE VETERINARY EDUCATION / AE / March 2007 77

a)

Lateral  b)  

Lateral   c)

 Fig 5: Transverse section of the right biceps brachii tendon. Numerous Haversian systems (white arrows) are separated by irregular interstitial systems (black arrows). This is typical of compact bone and demonstrates the ossification that occurred following dystrophic mineralisation. Haematoxylin and eosin stain: x10,000. Lateral



 Fig 4: (a) Cross-section of the normal (left) and of the abnormal Trauma can result in biceps brachii tendonitis and biceps brachii tendon (right) at the level of the humeral tenosynovitis. The unique constricted anatomical tubercles. Grossly, the abnormal tendon had the appearance of arrangement of the tendon, bursa and bone means that once cortical bone (due to ossification following dystrophic mineralisation) on the cranial aspect of the structure in the inflammation has been set up, it may easily be exacerbated region of the white arrow. (b) Caudal aspect of the normal (left) (Post and Benca 1989). Tendonitis and tenosynovitis of the and abnormal (right) biceps brachii tendon. The abnormal biceps brachii secondary to trauma can result in tendon is very roughened and fibrous. The normally smooth mineralisation in dogs and man (Post and Benca 1989; Flo bilobed structure is completely disrupted. (c) Normal (left) and abnormal (right) humeral tubercles and intertubercular groove. and Middleton 1990). McDiarmid (1999) reported tendon The abnormal tubercles are enlarged and abnormal in shape. mineralisation secondary to tendonitis in one horse. There are numerous fissures within the fibrocartilage of the Traumatic bicipital bursitis and tenosynovitis have both been abnormal humerus (white arrows). The medial tubercle and its associated with new bone formation on the humeral associated groove appear more irregular in shape (blue arrow). tubercles in the horse (Bohn et al. 1992; Grant et al. 1992). Mineralisation of the tendon has also been associated with forming hypertrophic bone (Meagher 1979). Metastatic healed fractures of the supraglenoid tubercle (Dyson 1985; mineralisation occurs commonly in man, where a calcium- Pankowski et al. 1986) and the greater tubercle (Allen and phosphorous imbalance exists from hereditary factors, White 1984). The advanced pathology in this case was hyperparathyroidism or renal disease. There is no support for suggestive of severe past trauma, such as a fracture of the this mechanism of mineralisation in the horse (Kawcak and supraglenoid tubercle. Due to the recent change of Trotter 1996). ownership no such history could be obtained.

TABLE 1: Terms used to describe the changes of soft tissue into bone. In the case of the mare in this report, dystrophic mineralisation occurred. The mineralisation then became ossified

Mineralisation The addition of mineral matter to a structure in the body. Dystrophic mineralisation The deposition of mineral in injured, degenerating or necrotic soft tissue structures. It is deposited as a result of direct trauma, infarction, haemorrhage or inflammation. Dystrophic material can ultimately become ossified due to extensive remodelling. Metastatic mineralisation The deposition of mineral in normal soft tissue structures such as muscles, tendons and connective tissue. It is deposited as a result of a calcium-phosphorous imbalance, hereditary factors, hyperparathyroidism or renal disease. Ossification The formation or conversion of a structure into bone. Calcification The deposition of calcium salts (as apposed to mineral tissue) in normal soft tissue structures. The causes are similar to those causing metastatic mineralisation. Metaplasia The change in the type of adult cell into a form abnormal for that tissue. Bone metaplasia is the formation of bone in a tissue that is not normally bone. 78 EQUINE VETERINARY EDUCATION / AE / March 2007

Tendon trauma causes inflammation, necrosis and tissue 1998). Acute cases of bursitis that are treated rapidly have the degeneration (Sarkar and Uhthoff 1978, Muir et al. 1992). This best prognosis (Reef 1998). Fifty-eight percent of horses with can result in the formation of fibrocartilage, which then has a acute tendonitis returned to full work, compared with only predilection for mineralisation via chrondrocyte-mediated 28% with the chronic condition (Gillis 1996). osteogenesis (Uhthoff et al. 1976; Post and Benca 1989; Muir et al. 1992; Kawcak and Trotter 1996). Alternatively, the Conclusion inflammation disturbs the ability of mitochondria to regulate calcium balance (Guyton and Hall 1996; Kawcak and Trotter This case report describes the clinical presentation, diagnosis 1996) resulting in dystrophic mineralisation. and post mortem findings in a case of biceps brachii tendon Conservative treatment of tendon mineralisation in horses, mineralisation. The findings demonstrate advanced pathology dogs and man consists of rest, anti-inflammatory medication, in this case despite only mild lameness on presentation. This cold therapy, therapeutic ultrasound, extra-corporeal case provides further evidence for the poor prognosis of horses shockwave therapy and controlled exercise (Post and Benca with advanced pathology of the biciptal bursa and tendon. 1989; Flo and Middleton 1990; Gillis and Vatistas 1997). Rest alone has been successful in only one horse presented with an Manufacturers’ addresses old healed supraglenoid tubercle fracture and associated 1 biceps brachii mineralisation (Dyson 1985). Anti-inflammatory Arnolds Veterinary Products Ltd, Shrewsbury, Shropshire, UK. 2Radiopharmacy Department, Royal Liverpool Hospital, Liverpool, UK. medication can be administered systemically or locally 3Vygon UK Ltd, Cirencester, Gloucestershire, UK. (intrathecally). Intrathecal medication (hyaluronan or 4Nuclear Diagnostics AB, Hägersten, Sweden. 5Siemens Aktiengesellschaft, Medical Engineering Group, Erlangen, Germany. polysulphated glycosaminoglycans) can be beneficial if the 6Dynamic Imaging Ltd, Livingston, West Lothian, UK. lameness improves to bursal analgesia (Adams and Blevins 7VWR International Ltd, Poole, Dorset, UK. 1989b; Dyson 1991). Intrathecal methylprednisolone acetate therapy has been successful in horses, man and dogs (Muir References et al. 1992; Stobie et al. 1995; Gillis and Vatistas 1997). However, complications thought to be associated with Adams, S.B. and Blevins, W.E. (1989a) Shoulder lameness in horses - corticosteroid therapy have included the formation of Part II. Comp. cont. Educ. pract. Vet. 11, 190-195. adhesions and the restriction of passive range of motion Adams, S.B. and Blevins, W.E. (1989b) Shoulder lameness in horses - (Vatistas et al. 1996), the development of necrosis and Part I. Comp. cont. Educ. pract. Vet. 11, 64-68. degeneration (Flo and Middleton 1990), mineralisation within Adams, M.N. and Turner, T.A. (1999) Endoscopy of the intertubercular bursa in horses. J. Am. vet. med. Assoc. 214, 221-225. the sheath and further tendon mineralisation (Edwards 1978; Allen, D. and White, N.A. (1984) Chip fracture of the greater tubercle Flo and Middleton 1990; Faure and Dieppe 1994) and the of a horse. Comp. cont. Educ. pract. Vet. 6, 39-41. delay in long-term calcium resorption (Re and Karzel 1993). Bassage, L.H. and Ross, M.W. (2003) Diagnostic analgesia. In: The success of extra-corporeal shockwave therapy in man has Diagnosis and Management of Lameness in the Horse, Eds: M.W. been very limited (Daecke et al. 2002). Conservative Ross, S.J. Dyson, W.B. Saunders, Philadelphia. pp 93-124. management had been unsuccessful in this mare. Since there Bleyaert, H.F. and Madison, J.B. (1999) Complete biceps brachii had been no improvement in the lameness following local tenotomy to facilitate internal fixation of supraglenoid tubercle analgesia, intrathecal treatment was not considered. fractures in three horses. Vet. Surg. 28, 48-53. Surgical management of biceps brachii tendonopathy in Bohn, A., Papageorges, M. and Grant, B.D. (1992) Ultrasonographic man and dogs includes tenotomy with the removal of the evaluation and surgical treatment of humeral osteitis and bicipital tenosynovitis in a horse. J. Am. vet. med. Assoc. 201, 305-306. calcified deposits, tenolysis of the transverse humeral ligament and tenodesis of the biceps brachii tendon by relocation to the Butler, J.A., Colles, C.M., Dyson, S.J., Kold, S.E. and Poulos, P.W. (2000) The shoulder, humerus and elbow. In: Clinical Radiology proximal aspect of the humerus (Lincoln and Potter 1984; Post of the Horse, 2nd edn., Blackwell Scientific Publications, Oxford. and Benca 1989; Flo and Middleton 1990; Muir et al. 1992; pp 205-243. Fossum et al. 1997). Tenotomy was successful in 2 equine Crabill, M.R., Chaffin, K. and Schmitz, D.G. (1995) Ultrasonographic cases and complete tendon transection was successful in one morphology of the bicipital tendon and bursa in clinically normal case. No horse suffered from shoulder instability or an inability Quarter Horses. Am. J. vet. Res. 56, 5-10. to extend the shoulder joint (Fugaro and Adams 2002). Daecke, W., Rusnierczak, D. and Loew, M. (2002) Long term effects of Following transection, there is thought to be reattachment of extracorporeal shockwave therapy in chronic calcific tendonitis of the shoulder. J. Shoulder Elbow Surg. 11, 476-480. the tendon to the scapula by fibrosis (Pankowski et al. 1986) and joint subluxation is unlikely due to the remaining Doherty, M. (1994) Calcium pyrophosphate dihydrate. In: Rheumatology, Eds: J.H. Klippel and P.A. Dieppe, Mosby, St Louis. stabilising forces (Bleyaert and Madison 1999). Transection pp 7,13.1-7,13.12. thus offers a possible surgical treatment option for Dyson, S.J. (1985) Sixteen fractures of the shoulder region in the mineralisation of the biceps brachii tendon. horse. Equine vet. J. 17, 104-110. The prognosis for cases of biceps brachii mineralisation is Dyson, S.J. (1986a) Shoulder lameness in horses: An analysis of 58 reported to be poor. Given the rarity of the condition no suspected cases. Equine vet. J. 18, 29-36. prognostic figures exist for the condition. The prognosis for Dyson, S.J. (1986b) Shoulder lameness in horses: diagnosis and nonseptic bursitis has been reported as guarded (Stashak differential diagnosis. Proc. Am. 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