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Updating Capsular Management in Hip Arthroscopy; Osteonecrosis Genetic Mutation Found; Mercy Health Wins AOSSM Systematic Review Award

Elizabeth Hofheinz, M.P.H., M.Ed. • Tue, August 9th, 2016

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New Techniques for Capsular Management in Hip Arthroscopy

Benjamin Domb, M.D., founder of the American Hip Institute, has worked for years to develop two specific techniques for capsular management in hip arthroscopy; one for the treatment of hip instability and the other for the treatment of femoroacetabular impingement (FAI).

The first involves hip arthroscopy with labral preservation and capsular plication in patients with borderline hip dysplasia. Dr. Domb told OTW, “Atraumatic micro instability, often associated with borderline dysplasia of the hip, is a recognized cause of groin pain and hip pathology. In the past, literature has shown some disastrous outcomes of arthroscopy in the setting of instability or dysplasia. This may be because arthroscopy involved an incision in the capsule, and sometimes removal of part of the capsule, which might compromise one of the static stabilizers of an already unstable hip.

“Almost a decade ago we began working on a technique to tighten the capsule arthroscopically in order to augment the stability of such hips after arthroscopic labral repair or reconstruction. We found that the use of arthroscopic capsular plication had very favorable results in patients with micro instability of the hip. However, this remains a very technical procedure, and if a great plication is not achieved, outcomes may be suboptimal in these patients.

“The intent of the approach is to preserve the capsule AND tighten it to add stability, in order to successfully treat this challenging group of patients.

“We previously published the results of our initial pilot study with 22 patients who had borderline dysplasia and who were treated with arthroscopic labral repair and capsular plication. To our knowledge this is the first report of outcomes of capsular plication in this population. Nonetheless, we needed to observe whether the repair would last, or whether the plicated capsule would stretch back out over time, in order to establish this as an alternative to periacetabular osteotomy (PAO) as an index treatment for borderline dysplasia.

“For that reason, we undertook to evaluate the outcomes of arthroscopic capsular plication and labral repair at minimum five year follow-up. In this study, with 25 hips (24 patients), the center edge angle in all patients was between 18 and 25. It is important to note we have advocated this procedure only in select cases of borderline dysplasia. In frank dysplasia—broadly speaking, LCEA [lateral center-edge angle]< 18—we advocate combined arthroscopy and PAO. Other factors which may push us toward PAO include ligamentous laxity or femoral deformities such as excess anteversion. We used four different patient reported outcome scores and Visual Analog Pain score; the outcomes were excellent out to five years. Four hips required secondary arthroscopic procedures, but ultimately had successful outcomes (with favorable patient reported outcomes). None of these patients required conversion to arthroplasty.

“A concern was that in the borderline dysplasia group, the arthroscopic capsular plication we devised would lack durability and that over time the lack of bony support would win over the capsular support we provided; so we were pleased to see that the outcomes appeared to be durable at five year follow-up with no conversions to arthroplasty in this group. These favorable mid-term outcomes, and 100% survivorship at minimum five years, have established the mid-term durability of arthroscopic capsular plication as a treatment for borderline dysplasia. We will continue to follow these patients closely, and will be comparing them to those undergoing alternative treatments.”

Dr. Domb’s second technique involves capsular closure after spherical femoroplasty for femoroacetabular impingement (FAI).

“We have come a long way in treating FAI, with hip arthroscopy taking center stage in the care of patients with this condition. In patients who don’t have dysplasia, the capsule is incised and sometimes part of it is removed. The American Hip Institute has long advocated that the capsule ought to be preserved and repaired.

“Our team undertook a comparative matched cohort study with 65 patients who had capsular repair and 65 patients who did not (the capsulotomy was left open). At five years we saw a significant improvement in all patients in both groups. However, in the unrepaired group at two to five years we did see a deterioration in the Harris Hip Scores and in patient satisfaction, while the outcomes were seen to remain equally favorable at five years in the repaired group. There were fewer patients in the repaired group who required conversion to arthroscopy (10.8 in the repaired group versus 18.3 in the unrepaired group).

“There are certainly patients who have severe stiffness or adhesive capsulitis, in whom incision or removal would be therapeutic. But for the majority of patients who do not have that scenario, we would advocate to preserve and repair the capsule. We hypothesized that the capsule is important in the stability of the hip. There are biomechanical studies showing that an unrepaired capsulotomy increases the rotation and translational instability of the hip. Thus we propose to restore the normal stability using capsular repair after treatment of FAI. We previously published two year follow up on this procedure, which demonstrate favorable results, and established safety and feasibility of the technique. This comparative study reveals the potential advantages of capsular preservation and repair in achieving durable outcomes and increased survivorship.

“In summary, we believe that current biomechanical and clinical evidence suggests that the capsule of the hip serves a valuable role. We believe that careful capsular management, with repair or plication as appropriate in the clinical setting, may lead to improved outcomes in patients with micro instability, and more durable outcomes in a majority of hip arthroscopy surgeries. We will continue to evaluate the long-term clinical outcomes, and to work toward making these procedures technically easier for the surgeon."

Hip Osteonecrosis: Genetic Mutation Found!

Canadian scientists just may have moved the needle when it comes to avoiding hip replacements. Researchers from the Research Institute of McGill University Health Centre (RI-MUHC) have found a new genetic mutation linked to osteonecrosis of the hip, specifically the femoral head.

Dr. Chantal Séguin is a hematologist-oncologist at the Bone Engineering and Vascular Biology Research Lab of the RI-MUHC, and senior author on the scientific paper published recently in the Journal of Medical Genetics. Dr. Séguin and orthopedic surgeon Dr. Ed Harvey co-direct the Osteonecrosis Clinic at the MUHC's Montreal General Hospital, where the researchers diagnosed advanced osteonecrosis in four out of six siblings in a family of European descent. Their team discovered a novel genetic mutation on a gene called TRPV4 (transient receptor potential vanilloid, a gene known for being vital in blood flow control and bone cell development.

Dr. Séguin told OTW, “There is no available biomarker in osteonecrosis that can detect the disease at an early stage before irreversible damage occurs. There are also no known medical treatments that will specifically target the pathway involved in osteonecrosis because the pathophysiology of the disease has not been well characterized. Hereditary osteonecrosis is very rare, and we have encountered only one family so far affected with the disease. Identifying a gene mutation behind hereditary osteonecrosis could help identify a potential pathway through which this disease develops.

“Gene mutations in Col2A1 (Collagen II Alpha 1) were the only genetic mutations identified so far in association with osteonecrosis, and mostly in people of Asian descent. Although our family is not of Asian descent, I was expecting to find a mutation in that same gene (Col2A1) or another collagen-based gene. We were surprised to find that mutations in Col2A1 gene were negative in our family. Mutations in Collagen 12 and Collagen 5 were also negative. I was surprised then to identify a calcium-permeable cation channel (TRPV4) to be involved, rather than a collagen-based gene and to be able to show a functional component brought by the mutation in two different types of cells.

“Part of the work being undertaken has to do with establishing causation between this mutation and the development of osteonecrosis in an animal model. We are also developing experiments to study the TRPV4 pathway itself and how it relates to the final bone necrotic process.”

Mercy Health Wins AOSSM Systematic Review Award

The orthopedics and sports medicine team at Mercy Health of Cincinnati, Ohio, has been honored with the 2016 American Journal of Sports Medicine (AJSM) Systematic Review Award from the American Orthopaedic Society for Sports Medicine (AOSSM). The work that garnered this award was focused on anterior cruciate ligament (ACL) injuries in young athletes.

Amelia Wiggins, D.O., told OTW, “Each year the AOSSM gives the Systematic Review Award to the best systematic review paper submitted to the American Journal of Sports Medicine. Having our paper accepted for publication and then winning this prestigious award was very exciting. It is a big honor, one our whole team was very humbled by. We hope our research will bring awareness to the high rate of re-injury in our young athletes after ACLR and encourage further research on the best ways to prevent injuries and protect our young athletes.

“Our review shows the incidence of re-injury in young patients (<20-25 years) who return to high-risk sports is 23%. This equates to a 30 to 40 times greater risk of an ACL injury compared with uninjured adolescents. Activity modification, improved rehabilitation and return-to-play guidelines, and the use of integrative neuromuscular training may help these at-risk athletes more safely reintegrate into sport and reduce second injury and should be encouraged.”

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