Minimally Invasive Orthopaedic Surgery

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

Minimally invasive orthopaedic surgery for the treatment of joint and bone problems, especially fractures, can rely on smaller skin incisions, reduced dissection of muscles, improved visibility with endoscopy and fluoroscopy, application of special instruments and robotic assistance, or some combination these. However, caution is prudent for the less experienced; successful minimally invasive surgery relies on the surgeon having considerable training and experience, and an intimate knowledge of the surgical anatomy.

A modification of the Cheli craniolateral arthrotomy reported by Vezzoni and colleagues vividly documents the surgical anatomy and approach to the canine shoulder joint for minimally invasive removal of osteochondritis dissecans cartilaginous flaps.[1] In their hands, the surgical time was short and the complication rate quite low in a large number of clinical cases. This is certainly a valuable alternative for a surgical approach to the canine shoulder for osteochondritis dissecans lesions. To determine how this minimally invasive approach compares to arthroscopic surgery, in terms of complications and long-term function outcome, it would need prospective clinical evaluation.

Stabilization of tibial tuberosity apophyseal avulsion fractures in 25 skeletally-immature dogs, reported by von Pfeil and colleagues, using percutaneous pinning could be completed in less than 20 minutes by experienced surgeons.[2] Although this closed approach precluded the application of a tension band wire, there were not any instances of implant or construct failure. The principal minor complications were seroma formation and patellar ligament desmitis, apparently due to irritation by the implanted pins. At follow-up, the mean tibial plateau angle was significantly less (18.8 degrees), compared with the contralateral normal stifle (23.1 degrees), apparently due to delayed growth or premature closure of the cranial portion of the proximal tibial plateau physis. Although outcome in these cases was considered excellent, this was not rigorously evaluated.

Normally, the tibial tuberosity apophysis (a secondary center of ossification) migrates proximally during tibial growth due to its close connection with the proximal tibial plateau epiphysis. Fixation of the tibial tuberosity apophysis with transversely orientated pins embedded into the proximal tibial metaphysis can effectively prevent further proximal growth or migration of this apophysis, even without the presence of a tension band wire. However, the patella can continue to maintain a normal relationship with the femoral trochlear groove, even in young growing dogs. This is apparent from examination of some of the radiographic images in this study[2] and in other studies.[3] In other words, the length of the patellar ligament increases, to keep pace with continued growth of the distal femoral and proximal tibial plateau physes, so that development of patella baja does not occur. How does this occur? Is there continued growth of the distal end of the patellar ligament at the enthesis on the tibial tuberosity apophysis? Or, is there interstitial growth and elongation of the juvenile patellar ligament? A recent study in immature rabbits found that epiphysiodesis of the distal femoral physis or the proximal tibial physis produced patella baja or patella alta, respectively.[4] By contrast with the observations in dogs,[2] there was not any compensatory over-growth in the patellar ligament in the rabbits.[4] This is considered to have changed the mechanics of the rabbit stifle joint which could have long-term functional consequences.[4]

The report by von Pfeil and colleagues[2] raises some interesting questions. Clearly, fixation of tibial tuberosity apophyseal avulsion fractures is a more complete problem than stabilization of such fractures and osteotomies in skeletally mature dogs, because of the potential involvement and continued growth of the associated physes as well as the different composition of the tissues affected. It would be useful to have a more clearly defined stratification of these fractures in growing dogs, based on prospective studies of long-term outcome.

Publication History

Article published online:
16 March 2021

• References

• 1 Vezzoni A, Vezzoni L, Boiocchi S, Miolo A, Holsworth IG. A modification of the Cheli craniolateral approach for minimally invasive treatment of osteochondritis dissecans of the shoulder in dogs: description of the technique and outcome in 164 cases. Vet Comp Orthop Traumatol 2021; 34 (02) 130-136
• 2 von Pfeil DJF, Megliolia S, Malek S, Rochat M, Glassman M. Tibial apophyseal percutaneous pinning in skeletally immature dogs: 25 cases (2016–2019). Vet Comp Orthop Traumatol 2021; 34 (02) 144-152
• 3 Goldsmith S, Johnson KA. Complications of canine tibial tuberosity avulsion fractures. Vet Comp Orthop Traumatol 1991; 4: 54-58
• 4 Dan MJ, Parr WCH, Crowley JD. et al. Moment arm function dictates patella sagittal height anatomy: rabbit epiphysiodesis model alters limb length ratios and subsequent patellofemoral anatomical development. J Orthop Res 2020; 14 DOI: 10.1002/jor.24714.