Evolution of Trochleoplasty for the Treatment of Medial Patellar Luxation: Rasp, Wedge, Block and Semi-cylindrical

Prof. Kenneth A. Johnson, MVSc, PhD, FACVSc, DACVS, DECVS.

For more than 50 years, the two fundamental procedures used for surgical correction of grade 2 and 3 medial patellar luxation in dogs have been the trochleoplasty and tibial tuberosity transposition. During this time, each of these two techniques has been modified, refined and improved considerably; they are sometimes performed alone, or in conjunction with other techniques such as distal femoral osteotomy, as part of a comprehensive approach to surgical correction of medial patellar luxation.

Originally the femoral trochlea was simply deepened with an osteotome or bone rasp, removing the hyaline articular cartilage and some underlying subchondral bone to ensure that the patella was more deeply located within the trochlear groove, thus preventing recurrent luxation.[1] Histological studies in the goat demonstrated that the denuded, exposed cancellous bone created by abrasion trochleoplasty became covered by fibrocartilage.[2] However, the new fibrocartilage layer was thin and uneven—an inferior substitute for the original hyaline cartilage.

In the early 1980s, it was Dr. Barclay Slocum of Eugene Oregon, the pioneer of the tibial plateau levelling osteotomy, who cleverly devised the trochlear wedge recession technique for surgical correction of recurrent patellar luxation.[3] The trochlear wedge recession technique allowed deepening of the femoral trochlear groove, while preserving the existing hyaline cartilage in the ‘floor’ of the groove. Furthermore, an experimental study demonstrated that the osteochondral wedge healed to the underlying cancellous bone bed by primary union, with preservation of the integrity of the overlying hyaline cartilage.[4]

Two decades later, Talcott and colleagues introduced a further modification to the wedge trochleoplasty whereby a rectangular shaped osteochondral block was created, rather than a wedge.[5] This become known as the block recession trochleoplasty; the creation of a new trochlear groove of uniform width throughout was considered to be an advantage over the trochlear wedge technique. However, the execution of the block recession trochleoplasty with a saw, osteotome and rongeurs was essentially free-hand, without any other special instrumentation to ensure accuracy of the osteotomies.

The semi-cylindrical recession trochleoplasty is a new method of creating the trochleoplasty.[6] A prospective, clinical, non-inferiority study of 10 dogs with bilateral medial patellar luxation reported in this issue of Journal found no differences in outcome variables between the semi-cylindrical technique and the block technique at 8 weeks after surgery.[6] In all cases, there were not any instances of reluxation of the patella at 8 weeks. The semi-cylindrical recession trochleoplasty was performed with a stainless-steel hole saw, with a diameter of 4 to 18 mm, in combination with a customized aiming guide. An advantage of the semi-cylindrical, rounded osteotomy is reduced risk of fracturing the femoral trochlear ridges. Second it could be performed in very small dogs.

This new semi-cylindrical recession trochleoplasty technique is very interesting, and we look forward to further long-term outcome studies, such as magnetic resonance imaging evaluation of integrity of the femoral trochlear hyaline cartilage.

Publication History

Article published online:
24 May 2021

• References

• 1 Singleton WB. The surgical correction of stifle deformities in the dog. J Small Anim Pract 1969; 10 (02) 59-69
• 2 Vaughan LC, Robins GM. Surgical remodelling of the femoral trochlea: an experimental study. Vet Rec 1975; 96 (20) 447-450
• 3 Slocum B, Slocum DB, Devine T, Boone E. Wedge recession for treatment of recurrent luxation of the patella: a preliminary report. Clin Orthop Relat Res 1982; (164) 48-53
• 4 Boone EG, Hohn RB, Weisbrode SE. Trochlear recession wedge technique for patellar luxation. An experimental study. J Am Anim Hosp Assoc 1983; 19: 735-741
• 5 Talcott KW, Goring RL, de Haan JJ. Rectangular recession trochleoplasty for treatment of patellar luxation in dogs and cats. Vet Comp Orthop Traumatol 2000; 13: 39-43
• 6 Blackford-Winders CL, Daubert M, Rendahl AK, Conzemius MG. Comparison of semi-cylindrical recession trochleoplasty and trochlear block recession for the treatment of canine medial patellar luxation: a pilot study. Vet Comp Orthop Traumatol 2020; 34: 183–190