A 12-year-old female neutered domestic shorthair cat was referred to our institution with slowly progressive bilateral forelimb lameness and a decreased range of motion (ROM) in extension of both carpal joints. No history of trauma, nor surgical intervention was reported. Clinical signs started 10 months prior to referral, consisting of right forelimb lameness that evolved, into carpal hyperflexion with a lack of carpal extension. Medical treatments were instigated by the referring veterinarian, including the use of steroidal (methylprednisolone 0.5 mg/kg q24h PO [Moderin; Zoetis]) and non-steroidal anti-inflammatory drugs (meloxicam 0.05 mg/kg q24h PO [Metacam; Boehringer Ingelheim]), but both were unsuccessful. Six months after signs were noted on the right forelimb, similar clinical signs were noted on the left forelimb.
Physical examination was unremarkable, except for the presence of generalised moderate muscle atrophy of both forelimbs detected on palpation. Neurological examination was unremarkable. The cat was reluctant to move, and a carpal flexural deformity (CFD) with a certain degree of distal valgus deviation, which was more pronounced on the left side, was noted (Figure 1). A subtle permanent flexion of the digits II-V was observed, which was more pronounced on the right forelimb. A firm, non-painful induration of the flexor retinaculum was palpated, secondary to the tension of the tendons at this level, compromising carpal ROM in extension. The hyperflexion and valgus deviation were irreducible, and an increased tension of the flexor muscles, in particular the flexor carpi ulnaris muscle (FCUM) at its insertion onto the accessory bone, could be palpated. No other abnormalities were palpated at the level of the flexor muscles bellies.
Blood urea nitrogen, creatinine, creatine kinase and total thyroxine values were within the reference intervals. Orthogonal radiographs of both forelimbs demonstrated a valgus deviation of the distal extremities (Figure 2). Ultrasound of the musculature and corresponding tendons of both forelimbs was performed, but no abnormalities were identified.
Owing to the severity of the clinical signs and the cat's discomfort, surgery consisting of a selective tenectomy of the contracted flexor muscles was proposed.The cat was premedicated with methadone (0.2 mg/kg IV [Comfortan; Dechra]), and induced with midazolam (0.3 mg/kg IV [Dormazolam; Dechra]) and alfaxalone (Alfaxan; Jurox Animal Health) to effect. Anaesthesia was maintained with 1-2% isoflurane in 100% oxygen, alongside a continuous rate infusion of fentanyl (5-12 microg/kg/h IV [Fentadon; Dechra]). The patient received lactated Ringer's solution (10 ml/kg/h IV) intraoperatively. Cefazoline (20 mg/kg IV [Cefazoline; Sandoz]) was administered every 90 mins. The patient was positioned in dorsal recumbency with the palmar surface of both forelimbs toward the surgeon. On the left forelimb, a palmarolateral skin incision of 4 cm was made, proximal to the antebrachiocarpal joint, followed by blunt dissection to expose the flexor muscle tendons. The tendons of the FCUM, flexor carpi radialis muscle (FCRM) and superficial digital flexor muscles (SDFMs) were isolated, and resection of a 5 mm long segment of these tendons was performed using a #11 scalpel blade. The tenectomies were performed in following order: first the FCUM, then the FCRM and finally the SDFM. A progressive resolution of the carpal hyperflexion was noted during the tenectomies.
On the right forelimb, a tenectomy of the FCUM tendon was performed via a curvilinear skin incision starting palmaromedial to palmarolateral and proximal to the right antebrachiocarpal joint (Figure 3).
Small skin incisions were made at the palmar surface of the second phalanx of the third and fourth digits of the right forelimb, allowing for selective tenectomy of the tendon branches of the deep digital flexor muscle (DDFM) of these digits (Figure 4). The tendon branches of the remaining digits were left intact, as these are not the major weightbearing digits, and we did not want to be too invasive. Muscular and tendinous biopsies of all sectioned tendons and associated muscles were taken intraoperatively. The subcutaneous tissues were closed using a simple continuous pattern with a 4-0 poliglecaprone 25 suture (Monocryl; Ethicon). The skin was apposed with an interrupted suture pattern with 4-0 polyamide (Ethilon II; Ethicon).
A bandage with the carpal joints at the maximal angle of extension was placed during the first 12 h postoperatively, and treatment with meloxicam (0.1 mg/kg q24h IV [Acticam; Ecuphar]) was initiated. Postoperative recovery was uneventful. Twelve hours postoperatively, a certain degree of hyperflexion of the carpal joints and a moderate bilateral forelimb lameness persisted (Figure 5). The cat was discharged 24 h postoperatively with meloxicam (0.05 mg/kg q24h PO for 5 days [Metacam; Boehringer Ingelheim]). Histopathology of the sectioned tendons revealed minimal leukocytic infiltration, compatible with peripheral chronic inflammation; however, an ischaemic aetiology could not be excluded. Histopathology of the muscles showed minimal signs of atrophy.
One month postoperatively, the cat was still moderately lame on the left forelimb with a partial palmigrade stance and a slight retraction of the second and fifth digits. An improvement in locomotion quality was noted by the owner.
Two months postoperatively, the cat presented with recurrence of clinical signs on the left forelimb, characterised by hyperflexion of the carpus and digits two, three and four, and valgus deviation. The region of the flexor retinaculum was again indurated due to tendons in tension. No abnormalities were observed on the right forelimb. A selective tenectomy was repeated on the left forelimb. The same anaesthetic protocol and surgical approach, as mentioned above, were used. Fibrous tissue connecting both ends of the tendon was present at the previous tenectomy sites. More tenectomies were performed over a length of 10 mm of the tendons of the FCUM, FCRM and SDFM proximally to the antebrachiocarpal joint. Also, the tendon branches of the DDFM of the second, third and fourth digits were sectioned. Twenty-four hours postoperatively, the lameness had improved slightly. The cat was discharged with meloxicam (0.05 mg/kg q24h for 7 days [Metacam; Boehringer Ingelheim]).
Follow-up after the second intervention occurred by phone contact. One month after the second intervention, the cat was free of lameness and had no CFD of the forelimbs. The Last follow-up was performed 6 months postoperatively. The cat was doing well, although it was showing a slight lameness on the left forelimb. The owner declined any follow-up consultation.