Desmotomy of the Accessory Ligament of the Superficial Digital Flexor Muscle in Equine Cadaver Limbs

Abstract

Effects of longitudinal compression before and after transection of the accessory ligament of the superficial digital flexor (SDF) muscle were measured in eight equine cadaver forelimbs. When compression was increased from 890 N to 3115 N, the metacarpophalangeal (MCP) and carpal joints hyperextended 20 degrees and 4 degrees, respectively, and strain in the SDF and deep digital flexor tendons was increased 3.5% and 1.4%, respectively. The accessory ligament did not elongate. Immediately after transection of the accessory ligament at 3115 N load, a 2.8 mm gap formed between the transected ends of the accessory ligament, and the muscle belly of the SDF elongated and moved distad. The MCP joint hyperextended 15.8% further and strain of the SDF tendon increased 11.2% further. These results show that the accessory ligament transferred load in the SDF musculotendinous unit away from the muscle belly and that desmotomy altered this function. Decrease in the MCP joint angle indicated that the accessory ligament contributed to the support of the MCP joint under load. Increase in SDF strain after desmotomy was probably influenced by the change in the moment about the MCP joint and increased length of the SDF musculotendinous unit.

Racing performance of Thoroughbreds with superficial digital flexor tendonitis treated with desmotomy of the accessory ligament of the superficial digital flexor tendon: 332 cases (1989–2003)

“…5 A case series of 131 National Hunt horses and 10 flat-racing Thoroughbreds treated with intralesional injection of bone-marrow-derived mesenchymal stem cells for SDFT has been reported. 7 In vitro cadaver studies 8,9 have shown increased strain in both the superficial digital flexor tendon and the suspensory ligament, under load, after acute SCLD. 6 Desmotomy of the accessory ligament of the superficial digital flexor tendon (ie, SCLD) has been proposed as a treatment based on the premise that transection and subsequent healing increase the check ligamenttendon length and reduce the likelihood of the tendon exceeding the maximum check ligament-tendon unit excursion, reducing the likelihood of reinjury.…”

Proximal Check Ligament Desmotomy

“…14 The actual strain in vitro on the SDFT after proximal check ligament desmotomy increases, but the elongation of the musculotendinous unit also increases during load application. 15 This elongation and recruitment of muscle fibers may allow for increased elasticity in the musculotendon unit compared with those that heal without desmotomy. 14 …”

Determination of passive mechanical properties of the superficial and deep digital flexor muscle-ligament-tendon complexes in the forelimbs of horses

“…[2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Induced strains on the SDF tendon, DDF tendon, and AL DDF during phases of gait have been determined via measurement of localized stretch with implanted transducers [2][3][4][5] or estimation of overall stretch by use of geometric models and measured limb kinematics. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Induced strains on the SDF tendon, DDF tendon, and AL DDF during phases of gait have been determined via measurement of localized stretch with implanted transducers [2][3][4][5] or estimation of overall stretch by use of geometric models and measured limb kinematics.…”

“…6,7 The passive resistance generated during stretch has been measured for isolated SDF 4,7-10 and DDF 4,7 tendons, as well as the AL DDF . 12, 13 The role of the accessory ligament in supporting the tendon loads has also been investigated for the AL SDF 14,15 and AL DDF . Alternatively, tendon loads have been estimated on the basis of each tendon' s contribution to joint moments calculated from kinematics and ground reaction force data.…”