Arthroscopically Assisted Core Decompression for Osteonecrosis of the Femoral Head Should Focus on Early Stages
Key findings
- Arthroscopically assisted core decompression is an emerging approach to femoral head preservation in cases of osteonecrosis of the femoral head (ONFH)
- In this retrospective cohort of 11 hips with ONFH, followed for an average of seven years (minimum, five years), six hips (54.5%) did not require total hip arthroplasty (THA)
- The risk of conversion to THA was significantly associated with Ficat-Arlet stage: none of three stage I lesions, one of four stage IIa lesions and all of four stage IIb lesions eventually required THA
- No major or minor complications were associated with arthroscopically assisted core decompression, including no femoral fracture or violation of the cartilage
- Arthroscopy allowed for the treatment of the entire hip joint by addressing concomitant intra-articular pathologies and alleviating mechanical symptoms
Osteonecrosis of the femoral head (ONFH) commonly affects relatively young patients in their 30s and 40s, and can result in substantial functional impairment. Optimal management is still debated, but it's generally agreed that it should depend on the stage of the necrosis.
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In the Ficat–Arlet staging system, stages 0 through IIb are considered precollapse and are considered eligible for femoral head-preserving surgery (arthroplasty is recommended for collapsed lesions). The most common approach to femoral head preservation is standard core decompression, which is technically straightforward and efficient.
Arthroscopic management of ONFH is a new and evolving approach for hip preservation, but few cohort studies have been published. In the longest-term retrospective follow-up study to date, Ali Parsa, MD, surgery fellow, Scott D. Martin, MD, director of the Joint Preservation Service within the Department of Orthopaedics Sports Medicine Center at Massachusetts General Hospital, and colleagues found that arthroscopically assisted core decompression is a promising approach to early-stage ONFH and can also successfully address concomitant intra-articular pathologies. Their findings are published in BMC Musculoskeletal Disorders.
Surgical Procedure and Subjects
The researchers identified eight patients (11 hips) who underwent hip arthroscopy by Dr. Martin between June 2007 and June 2013, had atraumatic ONFH with a stage I, IIa or IIb lesion and had been followed for at least five years. One of the eight patients was female and the others were male. The average age of the cohort was 36 (range, 17–48). The preoperative Ficat–Arlet classification was stage I in three hips, IIa in four and IIb in four. Four hips experienced mechanical issues before surgery: locking, catching or buckling.
The article describes the surgical and postoperative rehabilitation procedures in detail. The crux of the procedure was that a guiding pin was introduced through an incision on the lateral proximal thigh and was directed toward the necrotic lesion under direct fluoroscopic guidance. The placement and trajectory of the guide pin were verified arthroscopically. Subsequently, a 9-mm cannulated reamer was inserted over the guide pin, with placement again verified by fluoroscopy and arthroscopic visualization, and core decompression was performed.
The target of the reamer was the center of the necrotic area, and the surgeon aimed to maintain at least a 3-mm distance from the subchondral bone to prevent perforation of the cortical bone, articular cartilage and joint space.
Surgical Results
Arthroscopic verification of guide pin and reamer placement was achieved in all 11 surgeries. There were no minor or major complications, including no subtrochanteric fracture or violation of the articular cartilage.
The concomitant arthroscopic procedures required were labral repair/debridement in eight hips, repair of microfracture in seven, femoral osteochondroplasty in one and synovectomy in one.
Need for Total Hip Arthroplasty
The primary outcome measure of the study was subsequent conversion to total hip arthroplasty (THA). After an average follow-up of seven years, six hips (54.5%) had not required THA. For all of the five other hips, the indication for THA was symptomatic and radiographic progression of ONFH.
The risk of conversion to THA depended on the preoperative stage of ONFH:
- Stage I — zero of three hips required THA
- Stage IIa — one of four hips required THA
- Stage IIb — four of four hips required THA
For the five hips that converted, the average time from arthroscopy to THA was 23 months (range, 7–33 months).
Conversion to THA was significantly associated with Ficat-Arlet staging (P = .03) but not with bilateral hip involvement, mechanical symptoms, inhaled corticosteroid exposure (reported by two patients) or tobacco smoking (reported by four patients).
At the latest follow-up, the concomitant pathologies and mechanical symptoms had resolved. The six hips that did not convert to THA presented little to no pain and were unremarkable on clinical examination.
Conclusions
Arthroscopic management of ONFH is advantageous because it is both diagnostic and therapeutic. In addition, unlike percutaneous standard core decompression, arthroscopically assisted core decompression allows for arthroscopic treatment of intra-articular pathologies associated with ONFH.
Unfortunately, regardless of technique, a substantial portion of patients with ONFH will eventually require THA. Although this study has a small sample size, the findings indicate that arthroscopically assisted standard core decompression of ONFH is best restricted to early-stage lesions.
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