In this issue of Orthopedics, Dr Ernest Sink discusses the results from a new multicenter study involving seven North American centers that shows a low early complication rate following surgical hip dislocation.
In the multicenter study you conducted, you noted that the incidence of complications increased with age.1 Should surgical hip dislocation be avoided in this patient population?
Although the incidence was greater in patients older than 40 years, the complication rate was still low, and each of the complications was treatable. Therefore, it is a safe procedure for any age. The indications for surgery in the older age group are limited because after age 40, many of the impingement hips may have more advanced arthrosis. Although many of the recent published outcome studies include older patients, there appears to be more benefit for younger patients with less irreversible cartilage injury. Also, older patients have more comorbidities and poor bone quality, so surgeons should be judicious in patient selection.
In your chart review of 329 patients, 28 patients had reported complications, and of those, 14 were asymptomatic heterotopic ossification.1 Why do you believe heterotopic ossification accounts for 50% of the reported complications?
One of the reasons heterotopic ossification accounts for 50% of the overall incidence of complications is the low incidence of other complications. The gluteus medius and minimus muscles completely cover and are sharply dissected off the hip capsule during this approach. The surgeons goal is to retract these muscles with as little trauma as possible. The surgical dislocation approach explores natural tissue intramuscular planes to visualize the hip capsule, attempting to create as little muscle injury as possible. Yet due to muscle retraction in this region, the potential exists for heterotopic ossification. Many patients treated for hip impingement are muscular, athletic men; thus, there may be a greater potential for heterotopic ossification from muscle dissection and retraction needed for effective exposure in these individuals. Fortunately, the incidence of heterotopic ossification is rare and has no clinical relevance. The surgeons proficiency and experience may help decrease the incidence of heterotopic ossification.
What explanation can be given for the overall low complication rate?
Surgical hip dislocation is a safe approach to the hip. It is performed in relatively healthy young patients with few or no comorbidities. There are no vascular or nervous structures directly at risk from the approach or from tissue retractors. All of the surgeons who participated in our study are well trained in the technique, have a lot of experience with surgical hip dislocation, and have high-volume hip surgery practices, which also plays an important role in reducing the incidence of complications. Finally, we owe Professor Ganz2 and his colleagues credit for careful development of the approach to achieve hip dislocation without producing osteonecrosis and relying on safe tissue planes for dissection.
How much of an effect does approach (anterior vs posterior) have on outcomes?
This depends on various factors. Most approaches to the hip joint (anterior and posterior) are safe; they use natural tissue plains and give access to different areas of the hip. If only the anterior region of the hip needs access, the anterior approach will give just as good an outcome, eg, irrigation for sepsis. If access is needed to visualize the entire hip joint, a surgical hip dislocation will likely give the best outcome from an open perspective because of the ability for complete visualization such as a complex mixed cam and pincer impingement. The condition being treated and specific indications will determine the approach. We hope to have a better answer after carefully controlled outcome studies.
Is there a potential for damage to the vascularity of the femoral head with surgical hip dislocation, and if so, how much?
I am unaware of any cases of osteonecrosis occurring after surgical hip dislocation without an additional osteotomy. We had no cases in our study, nor have any cases been reported of osteonecrosis in studies using surgical hip dislocation. A few cases of osteonecrosis have occurred if an osteotomy was also performed, such as a reduction of a slipped capital femoral epiphysis or a concurrent intertrochanteric osteotomy performed through a surgical dislocation approach. Therefore, although a potential exists for damage to the vascularity, it is extremely rare.
What benefits does surgical hip dislocation afford to the patient?
Surgical dislocation allows full visualization for any complex pathologic hip condition. It is a safe and effective approach to managing femoroacetabular impingement. With this approach, labral repair, acetabular rim trimming, and osteochondroplasty can be easily performed. Many other diseases can be managed with this approach, such as slipped capital femoral epiphysis and painful residual Perthes deformity. Patients with complex hip deformities can benefit from the surgeons ability to safely visualize and treat the pathology.
- Sink EL, Sucato DJ, Kim, Y-J, Dayton MR, Clohisy JC, Zaltz I. Multi-center evaluation of early complications following surgical hip dislocation. Paper presented at: 2009 Annual Meeting of the American Academy of Orthopaedic Surgeons; February 2009; Las Vegas, Nevada.
- Ganz R, Gill TJ, Gautier E, Ganz K, Krügel N, Berlemann U. Surgical dislocation of the adult hip a technique with full access to the femoral head and acetabulum without the risk of avascular necrosis. J Bone Joint Surg Br. 2001; 83(8):1119-1124.
Dr Sink is Medical Director of the Hip Program, The Childrens Hospital, and Assistant Professor, University of Colorado Health Sciences Center, Aurora, Colorado.
Dr Sink has no relevant financial relationships to disclose.