Partial parasagittal patellectomy: a novel method for augmenting surgical correction of patellar luxation in four catsby L. Rutherford, G. I. Arthurs

Journal of Feline Medicine and Surgery


Small Animals


Journal of Feline Medicine and Surgery 2014, Vol. 16(8) 689 –694 © ISFM and AAFP 2013

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DOI: 10.1177/1098612X13509996

Patellar luxation (PL), its surgical management, outcome and complications are well described in the dog.1–5

However, there is little published about PL in the cat.6–8

Knowledge of feline orthopaedic disease and treatment are frequently assumed to be equivalent to that required for small dogs. Management of feline orthopedic disease is frequently adapted from techniques for the canine patient without consideration of anatomical features unique to the cat.9 One feature of the feline stifle is that the patella is wider in a medio-lateral direction relative to the femoral trochlear sulcus, and flat in the craniocaudal plane.9 Unlike dogs, many clinically normal cats have mediolateral laxity of the patella with respect to the sulcus. It is recognised that patellar subluxation is a common finding in the normal cat.7–9

Cats with patellar subluxation or low-grade PL may have no clinical signs. A cross-sectional prevalence study found that 45/78 cats (58%) had PL and 78% of the cats with PL had a grade 1 luxation, but only 11 cats (24%) had pelvic limb lameness.7,10 Medial patellar subluxation was seen in 31/33 cats (94%) with otherwise normal stifle joints and no lameness.7 Although patellar subluxation is a common finding in cats, PL is an infrequent clinical problem, but, when present, it can cause pelvic limb dysfunction presenting as pelvic limb lameness, intermittent locking of the stifle or a crouched stance.6

Surgical and non-surgical management of feline PL can result in excellent clinical outcomes.8,11 Loughin et al8 recommend surgical management for cats with persistent lameness refractory to conservative management.

Surgical techniques commonly employed for correction of PL in dogs include femoral trochleoplasty, tibial tuberosity transposition (TTT), soft tissue imbrication and/or release, and femoral corrective osteotomies.1,4,12

Combinations of these techniques are performed on a single stifle. The same techniques are utilised in cats, but the literature does not address how to apply them to cats nor whether their application should be different from dogs.8

We have noticed that, compared to dogs, applying these techniques does not always achieve intraoperative patellar stability in cats. Our intraoperative assessment in such cases has been that the wide and flat shape of the

Partial parasagittal patellectomy: a novel method for augmenting surgical correction of patellar luxation in four cats

Lynda Rutherford1 and Gareth I Arthurs2*


We describe a novel surgical technique used to correct feline patellar luxation (PL) where abnormal patellar tracking persists despite conventional corrective surgery. An anatomical difference between feline and canine stifles is that the feline patella is wider relative to the trochlear sulcus. This results in less constrained patellar tracking. Therefore, patellar subluxation is common in normal cats. It was noticed that in some feline cases with clinically significant PL,

PL persisted intraoperatively despite performing the standard corrective procedures. We report a novel surgical technique – partial parasagittal patellectomy – to address the wide shape of the feline patella relative to the sulcus.

This technique has been successfully performed in four cats with good outcomes. However, the immediate risks and long-term effects of partial parasaggital patellectomy are not known. We reserve this technique for surgical cases where PL cannot be controlled by conventional means.

Accepted: 1 October 2013 1Royal Veterinary College, Queen Mother Hospital for Animals,

Hatfield, UK 2Royal Veterinary College, Hatfield, UK *Current address: Arthurs Orthopaedics, Towcester Veterinary

Centre, Towcester, Northamptonshire

Corresponding author:

Lynda Rutherford BVM&S, MRCVS, Royal Veterinary College,

Queen Mother Hospital for Animals, Hawkshead Lane, Hatfield,


Email: 509996 JFM16810.1177/1098612X13509996Journal of Feline Medicine and SurgeryRutherford and Arthurs 2013

Case Series at Selcuk Universitesi on January 28, 2015jfm.sagepub.comDownloaded from 690 Journal of Feline Medicine and Surgery 16(8) feline patella relative to the femoral trochlear sulcus hinders stable tracking of the patella. To address this and prevent persistent PL, we have developed the novel surgical technique of partial parasagittal patellectomy. The purpose of this report is to describe the surgical technique and to report a series of cases.

Case descriptions

Four cats had partial patellectomy for persistent PL (Table 1). The same lead surgeon (GA) performed all the surgeries in the same procedural order as described in

Table 1. Pre- and postoperative radiographs were taken for all cases (Figure 1a,b, Figure 2a, b). All of the cats were hospitalised for 2–4 days postoperatively. Peri- and postoperative analgesia consisted of injectable opiates (methadone [Physeptone; Glaxosmithkline] or buprenorphine [Vetergesic; Alstoe Animal Health]) and oral meloxicam (Metacam; Boehringer Ingelheim). Gentle physiotherapy and cold compresses were applied several times daily to those cats that would allow it. The cats were discharged with instructions that included exercise restriction in the form of cage rest for 6 weeks, with 5–10 minutes of supervised gentle, room-confined exercise and passive range-of-motion physiotherapy.

Case 1 Case 1 was a 1-year-old Maine Coon with grade 2 left medial patellar luxation (MPL). A lateral parasagittal patellar arthrotomy was made. Femoral wedge trochleoplasty was performed after arthrotomy and intraarticular assessment. Quadriceps alignment was assessed and corrected by lateral TTT. Medial and lateral soft tissue tensions were assessed and were normal; therefore, lateral

Figure 1 Preoperative craniocaudal (a) and mediolateral (b) radiographs of case 4 demonstrating a grade 3 medial patellar luxation and relatively wide patella compared with the trochlear widthTa b le 1