Clinical Orthopaedics and Related Research ®

A Publication of The Association of Bone and Joint Surgeons ®

Does Surgeon Experience Impact the Risk of Complications After Bernese Periacetabular Osteotomy?

Eduardo N. Novais MD, Patrick M. Carry BA, Lauryn A. Kestel BS, Brian Ketterman BS, Christopher M. Brusalis BA, Wudbhav N. Sankar MD



Bernese periacetabular osteotomy (PAO) is a technically challenging procedure with potential risk for major complications and a previously reported steep learning curve. However, the impact of contemporary hip preservation fellowships on the learning curve of PAO has not been established.


(1) What was the frequency of major complications during the PAO learning curve of two surgeons who recently graduated from hip preservation fellowships? (2) Is increasing level of experience associated with the risk of a complication and with operative time, a possible surrogate measure of surgical performance?


We retrospectively studied 81 PAOs performed by one of two surgeons who recently graduated from a hip preservation fellowship during their first 4 years of practice in two institutions. One of the surgeons participated as a fellow in 78 PAOs with an increasing level of responsibility during the course of 1 full year. The other surgeon performed 41 PAOs as a fellow during 6 months, also with an increasing level of responsibility during that time. There were 68 (84%) female and 13 (16%) male patients (mean age, 18 years; range, 10–36 years). The frequency of complications was recorded early and at 1 year after surgery and graded according to a validated classification system describing five grades of complications. Complications that required surgical intervention (Grade III) and life-threatening complications (Grade IV) were considered major complications. Persistent pain after surgery, although considered a failure of PAO, was not considered a surgical complication as a result of the multifactorial etiology of pain after hip-preserving surgery. However, early reoperation and revision surgery were counted as complications. To evaluate the association between increasing level of experience and the occurrence of complications, we divided each surgeon’s experience into his first 20 procedures (initial interval) and his second 20 (experienced interval) to test whether the incidence of complications or operative time was different between the two intervals. Because the association between experience and the likelihood of a complication was estimated to be consistent between the two surgeons, the analysis was performed with data pooled from the two surgeons. To test whether there was a difference in the likelihood of a complication in the initial and the experienced intervals, a multivariate logistic regression analysis was performed and the adjusted risk of a complication between the two intervals was calculated. Linear regression analyses were used to test the association between surgeon level of experience and operative time.


The overall incidence of major (Grade III or Grade IV) complications was 6% (95% confidence interval [CI], 2%–14%). These included deep infection (3% [three of 81]), intraoperative posterior column fracture (1% [one of 81]), and pulmonary embolism (1% [one of 81]). With the numbers available, the risk of a complication did not decrease with increasing surgeon experience. After controlling for body mass index and surgeon, the frequency of a complication did not decrease in the experienced interval relative to the initial interval (odds ratio, 0.78; 95% CI, 0.25–2.4; p = 0.6623). The adjusted risk difference between the experienced interval relative and the initial interval was 6% (95% CI, −11% to 23%). When experience was modeled as a continuous variable (number of PAOs performed), increasing experience was not associated with a lower likelihood of a complication (odds ratio per one PAO increase in experience, 0.99; 95% CI, 0.94–1.04; p = 0.5478). However, after adjusting for body mass index and surgeon, increased experience was associated with a reduction in operative time (slope [change in log operative time per one procedure increase in experience], −0.005; 95% CI, −0.009 to −0.0005; p = 0.0292). For every one additional PAO increase in experience, there was a 0.45% decrease in operative time (95% CI, 0.05%–0.86% decrease].


With a case exposure greater than 40 PAOs and progressive surgical responsibility during contemporary structured training, two young surgeons were able to perform PAO with a low risk of complications. However, even with that surgical experience before independent practice, surgical time decreased over the first 40 PAOs they performed independently. Our data may help guide orthopaedic residency and hip preservation fellowship programs in establishing training requirements and assessing competency in PAO.

Level of Evidence

Level III, therapeutic study.

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