Treatment of a subchondral cystic‐like lesion in the distal scapula with a translesional bone screw in a horse

Abstract

Summary A 2‐year‐old French Warmblood stallion was presented for lameness investigation. The diagnostic procedures identified the reason for lameness as being a subchondral cystic‐like lesion (SCL) in the glenoid cavity of the scapula. The horse was surgically treated with a translesional 4.5 mm cortical bone screw inserted through the SCL under radiographic guidance. Sixty days after surgery, the horse was sound and the SCL showed significant radiographic signs of healing. Radiographs obtained 180 days after surgery showed further radiographic healing, with the SCL presenting a radiodensity similar to the surrounding bone. At 4 years post‐operative follow‐up, the horse is sound and competing successfully as a 6‐year‐old in Concours de Saut International (CSI) competitions.

Treatment of osseous cyst‐like lesions

“…The trans‐cystic screw employed in the case report by Corraretti et al (2021) is a recent popular addition to the surgical treatment repertoire and is based on the ability of trabecular bone to adjust and realign to the peak loading direction and the hypothesis that the screw returns trabecular bone strain to the interior of the OCLL. By altering the biomechanical environment of OCLLs, the screw is expected to promote bone healing and thus provide a foundation for attachment of remaining hyaline cartilage, prevention of contact of joint fluid with damaged bone, and load transfer (Santschi et al 2015; Frazer et al 2019a, 2019b; Frazer et al 2020).…”

“…The 2‐year‐old French Warmblood stallion described in the associated case report (Corraretti et al 2021) showed intermittent 2/5 (AAEP scale) left forelimb lameness with a shortened cranial phase of the stride and was diagnosed with an OCLL in the caudal half of the glenoid cavity of the scapula with no other radiographic abnormalities of the scapulohumeral joint. Osteochondrosis of the scapulohumeral joint (SHJ) is considered to be the most severely debilitating form of osteochondrosis in the horse, due to the constant loading of the majority of the glenoid articular cartilage (Nyack et al 1981; Jenner et al 2008).…”

“…Accordingly, there is little experimental or clinical data to base treatment decisions on. In the accompanying case report, Corraretti et al (2021) decided to treat the OCLL with a unicortical, trans‐cystic 4.5 mm (50 mm long) self‐tapping cortical screw placed in neutral fashion in a lateromedial direction across the OCLL without drilling through the axial trans cortex of the scapula to avoid iatrogenic damage to the brachial plexus and axillary artery and vein, with the intention to stabilise the cystic area and to promote bone healing. Given the reported poor holding strength of screws placed in the scapula (Ahern et al 2017), the narrow dimension of the scapula in a lateral to medial plane and the comparatively large size of the cyst (19 × 28 mm), the screw could only engage limited bone stock on the far side of the cyst, raising doubt whether biomechanical stabilisation of the cyst could contribute much to the successful outcome of this case.…”

“…Should cyst decompression indeed significantly contribute to the healing response, use of a cannulated screw might enhance the therapeutic effect (Pretell‐Mazzini et al 2014; Noordin et al 2018). The interesting case report by Corraretti et al (2021) introduces another treatment option for management of this rare condition, which to date has been associated with a poor prognosis for return to full athletic function.…”

“…The OCLL described in the accompanying case report 'Treatment of a subchondral cystic-like lesion in the distal scapula with a translesional bone screw in a horse' by Corraretti et al (2020), in a 2-year-old French Warmblood not yet in training, with no history of trauma, can likely be categorised as a developmental lesion arising secondary to osteochondrosis. Osteochondrosis, defined as a focal disturbance of endochondral ossification leading to the development of osteoarticular lesions (osteochondrosis dissecans or OCLLs) at specific predilection sites of predisposed joints, affects 10-30% of the equine population as well as other species such as pigs, dogs, cattle, sheep, poultry and also humans (Rejn€ o and Str€ omberg 1978;Desjardin et al 2014;Naccache et al 2018).…”