Editorial Commentary: Interportal Capsulotomy for Hip Arthroscopy in Patients With Borderline Hip Dysplasia May Result in Inferior Outcomes: Periportal Capsulotomy May Reduce Hip Capsular Damage

Optimal management of the hip capsule remains to be an ongoing discussion in the field of hip arthroscopy. Interportal and T-capsulotomies remain the most common methods of opening the capsule, and biomechanical and clinical studies have largely found superior benefits to routine capsular closure when these types of capsulotomies are performed. Although there is an increasing trend toward capsular closure, less is known, however, about how well the capsule heals after repair. Weber et al. evaluated MRIs at 1-year after surgery following T-capsulotomy repair and found that the majority (92.5%) of capsular repairs had remained closed. This is an important finding, but it does not assess for the quality of the capsular tissue at the repair site. We must not forget that while the capsular tissue may heal back together, repaired ligamentous tissue will never regain the same biomechanical properties as it had prior to being disrupted. And for patients with borderline hip dysplasia, where the hip capsule plays an integral role in maintaining hip stability, this becomes an even more important consideration when it comes to hip capsule management.

In the article, “Patients With Unhealed or Partially Healed Anterior Capsules After Hip Arthroscopy for Borderline Developmental Dysplasia of the Hips Have Inferior Patient-Reported Outcome Measures” by authors Yang, Zhang, Xu, Huang, and Wang, a retrospective analysis of interportal hip capsule repairs in patients with borderline hip dysplasia revealed a high proportion of poorly healed capsular repairs (44%, 26/59) at minimum 2-year follow-up. Further, these patients with insufficiently healed, or partially healed (as described by the authors), capsular repairs had significantly lower patient-reported outcomes (PRO) than patients who had no capsular thinning at the repair site after surgery. Patients with unhealed or partially healed repairs were also less likely to achieve minimum clinically important differences (MCID) or patient-acceptable symptomatic states (PASS) for the Hip Outcome Score–Activities of Daily Living (HOS-ADL). These are important findings, as they demonstrates that while most capsular repairs remain closed at follow-up—with 93.2% remaining closed in the current study, similar to the rate reported by Weber et al. of 92.5%—the tissue quality at the repair site may not heal fully and can result in poor functional outcomes. It should be noted that the authors used their own definition of partially healed, with a postoperative capsular thickness ½ the standard deviation below the mean preoperative capsular thickness as the definition of partial healing, so the rates of partially healed repairs cannot be compared easily with other reports in the literature. Nonetheless, the authors identified the important finding that for patients with borderline hip dysplasia, there is a high rate of failure to reconstitute the hip capsule to preoperative thickness following an interportal capsulotomy repair, and the impact of this capsular thinning is associated with inferior functional outcomes.

A particularly notable finding from this study was the high proportion (44%) of patients who had persistent hip capsule thinning at more than 2 years after capsular repair. The authors evaluated for variables associated with partially healed capsules, but there was no difference in age, BMI, sex, preoperative radiographic parameters, or intraoperative procedures performed, including capsular management with either a repair or lift tightening between groups. One important variable not evaluated by the authors was joint hypermobility, a factor known to be associated with hip dysplasia. The evaluation of joint hypermobility with a metric such as a Beighton score, might have revealed that patients with increasing joint hypermobility are at an increased risk for partially healed capsules. It is known that patients with connective disorders, such as Ehlers-Danlos, are prone to delayed tissue healing and abnormal scarring, so this may be worth consideration in future research.

Given the apparent high risk for partially healed capsules after interportal capsulotomy repair for patients with borderline hip dysplasia—might there be a better option for capsular management in these patients? The utilization of a periportal capsulotomy might present a possible solution for this problem. It has been demonstrated that a periportal capsulotomy can provide safe access to the hip joint and allow for sufficient ability to treat femoroacetabular impingement and decompress cam morphology. With this method, the capsule is minimally violated, which, in many cases, may not even necessitate closure. MRI evaluation of hip capsules 1 year after periportal capsulotomy without closure demonstrated good healing, although there was some evidence of reduced anterior hip capsule thickness compared to preoperative values. The study was performed on patients without borderline dysplasia, which as discussed is a key consideration when determining the approach to capsule management. Thus, the use of a periportal capsulotomy followed by closure at the end of the procedure, such as that described by Alrabaa et al., might be a reasonable approach to capsule management in patients with borderline hip dysplasia. Outcomes following periportal capsulotomy repairs in the setting of femoroacetabular impingement and generalized ligamentous laxity (Beighton score ≥ 4) are currently being studied at our institution, and preliminary findings at 2-year follow-up have identified that GLL patients undergoing capsular repair have PRO improvements similar to patients without ligamentous laxity who did not undergo capsular repair.

In conclusion, this study highlights the importance of optimizing capsular management during hip arthroscopy, particularly in the setting of borderline hip dysplasia. Patients in this population may be at higher risk for inadequate healing of their ligamentous tissue at capsulotomy repair sites, which can result in inferior functional outcomes. One potential option to limit capsule violation and prevent the resultant need for capsular tissue healing is to reduce the size of tissue violation altogether, such as with the use of a periportal capsulotomy. Further research is needed, however, to fully understand the healing of various capsulotomy types and the implications they have on postoperative outcomes.