High Body Mass Index is Related to Increased Perioperative Complications After Periacetabular Osteotomy

DISCUSSION

There have been 4 previously published articles specifically on complications following PAO. Each of these encompassed follow-up visits including both the perioperative period and at least 2 years of follow-up.^20,22,24,29 Davey and Santore²⁹ reported an overall rate of complications of 10% in a series of 70 patients. These authors classified complications into minor, moderate, and major for purposes of research and discussion, and this classification system has been utilized or modified within the literature to discuss complications in most other articles. Complications within the perioperative period included 2 cases of excessive intraoperative bleeding, 2 cases of reflex sympathetic dystrophy, and 1 case each of unresolved sciatic nerve palsy and deep vein thrombosis.²⁹ Hussell and colleagues²² reported on a large series of 508 PAOs and analyzed the technical complications that occurred during the procedure and caused either immediate or longer-term problems for the patients. Notably, they concluded that 85% of the technical complications occurred with the initial 50 PAOs performed, signifying a steep learning curve for this technically demanding procedure. Perioperative complications reported were intra-articular osteotomy in 2.2%, femoral nerve palsy in 0.6%, sciatic nerve palsy in 1.0%, posterior column insufficiency in 1.2%, and symptomatic hardware in 3.0%.²² Biedermann and colleagues²⁰ found that 47 out of 60 PAOs in their series had at least 1 minor complication. The most common perioperative complications were lateral femoral cutaneous nerve dysesthesia in 33%, delayed wound healing infection in 15%, major blood loss in 8.3%, sciatic or peroneal nerve palsy in 10%, posterior column discontinuity in 6.7%, and intra-articular osteotomy in 1.6%.²⁰ Most recently, complications of PAO in an adolescent population were evaluated.²⁴ The overall rate of complications was 37%. Major perioperative complications included 1 patient with excessive bleeding due to an aberrant artery at the medial wall of the pelvis thought to be due to revascularization following a previous Dega osteotomy. Two patients required immediate revision of the osteotomy due to excessive anterior coverage noted on postoperative radiographs. There were 5% with superficial stitch abscess causing minor infection, 5% with transient lateral femoral cutaneous nerve palsy, and 15 patients with symptomatic hardware.²⁴

At 12.5%, our overall complication rate is slightly lower than that previously reported in the literature. This may be due to the difference in the scope of this study, which reported only perioperative complications. We also chose to utilize the modified Clavien-Dindo classification system for reporting our complications rather than classifying them as minor or major as in the above studies. This classification system has been validated for use in reporting complications of hip preservation surgery. We considered only Grade II complications and higher for statistical analysis as these required a change in postoperative management, which may have artificially lowered our complication rate.

The data in this study indicate that, compared with patients with a BMI of <30, obese patients have a higher rate of perioperative complications and reoperations. Additionally, the proportion of Grade II and higher complications, importantly deep infection, was higher in obese patients. We did not have any reported incidence of deep vein thrombosis or pulmonary embolism, urinary tract infection, intra-articular osteotomy, acetabular or pelvic fracture, femoral or sciatic nerve palsy, or long-term lateral femoral cutaneous nerve palsy in this series of patients. The most common complication in the low-BMI group was symptomatic hardware. Sixteen patients had this complaint; however, this was not considered a Grade II complication as there would be no change in management during the study period, including the perioperative time frame. Two out of 4 patients with diabetes mellitus developed wound infections, both of which required reoperation. However, the number of patients with diabetes mellitus was not large enough to draw any conclusions from this information. There were no perioperative complications in smokers. We hypothesized that there may be a higher rate of wound complications in this population, and although the data in our patients did not support this hypothesis, a larger cohort of smokers is needed to make this determination. Another potential complication in smokers is non-union, which was not reported in this study on perioperative complications. Although it did not reach statistical significance, the intraoperative blood loss was almost 150 mL greater in high-BMI patients (924 mL vs 779 mL). Additionally, there appears to be no effect of concomitant procedure on estimated blood loss in either low- or high-BMI groups. Age was not a risk factor for the development of perioperative complications in this cohort. Pain was reliably improved in both the high- and low-BMI groups at the 12-week follow-up visit. The center-edge angle could be normalized in both groups to 28.53° in the high-BMI group and 27.07° in the low-BMI group, with a similar final correction between groups. The Tönnis angle was also improved in both groups, but the final Tönnis angle strongly trended toward statistical significance (2.79° in the low-BMI group vs 10.06° in the high-BMI group).

This study has limitations in that it is a retrospective review of patient information based on medical records and therefore relied on documentation performed at the time of service. There also may have been a difference in the intraoperative or postoperative protocol for wound monitoring or rehabilitation among patients based on body habitus, which we are not able to detect from the medical records. Although the overall number of patients in this cohort is comparable to other studies on the outcomes of patients after PAO, the number of patients in each BMI group was not evenly matched. Without randomization, selection bias occurred at the time of the procedure as some obese patients were not offered this procedure based on the senior surgeon’s discretion. Additionally, when subgroups such as patients with diabetes mellitus or smokers were analyzed, the number of subjects was too small for statistical analysis; therefore, no conclusions could be made as to the risk of perioperative complications in these populations.

CONCLUSION

Despite the limitations in this study, based on the data from this cohort, we concluded that the goal of PAO of restoring more normal hip joint anatomy can be achieved in both low- and high-BMI patients. However, patients with a BMI >30 should be counseled on their increased risk of major perioperative complications, specifically wound dehiscence and infection, and the higher likelihood of reoperation for treatment of these complications. Diabetic patients can be counseled that they may have a higher risk of infection as well, but future studies with larger numbers will be needed to confirm this. Patients with low BMI should be counseled about the potential for prominent or symptomatic hardware, which may necessitate removal following osteotomy union.