BACKGROUND: Primary synovial osteochondromatosis of the hip, a rare benign condition characterized by multiple intra-articular osteochondral loose bodies and synovial hyperplasia, may result in mechanical symptoms and degenerative arthritis if untreated. The purpose of this study was to report the results of arthrotomy alone or combined with anterior dislocation of the hip to perform synovectomy and removal of loose bodies in patients with this condition.
METHODS: We retrospectively reviewed a consecutive series of twenty-one patients (twenty-one hips) with primary synovial osteochondromatosis of the hip treated with open surgical débridement. On the basis of the extent of extra-articular involvement as seen on preoperative magnetic resonance imaging, eight of the twenty-one patients underwent synovectomy and removal of loose bodies following anterior dislocation of the hip and thirteen underwent the same procedure with arthrotomy alone. At a mean of 4.4 years postoperatively, the patients were assessed clinically and radiographically with special attention to disease recurrence, osteoarthritis progression, and surgical complications.
RESULTS: The mean Harris hip score for the entire series of patients improved from 58 points preoperatively to 91 points at the time of the latest follow-up. Eighteen of the twenty-one patients had a good or excellent clinical result, and seventeen patients were satisfied with the result of the surgery. The clinical scores, patient satisfaction scores, and radiographic grades of osteoarthritis at the time of the latest follow-up did not differ significantly between the group treated with dislocation and the group treated without dislocation. Symptomatic disease recurred in two of the thirteen hips treated with arthrotomy alone and in none of the hips that had undergone dislocation. However, the surgical complication rate was higher in the group treated with dislocation than it was in the group treated without dislocation (p = 0.042). While patients with some signs of mild osteoarthritis at the initial procedure had a higher rate of osteoarthritis progression, severe osteoarthritis requiring arthroplasty had developed in only one patient at the time of follow-up.
CONCLUSIONS: At a mean of 4.4 years postoperatively, we found that open synovectomy and removal of loose bodies for the treatment of primary synovial osteochondromatosis of the hip is a reliable procedure that can effectively relieve symptoms. Our results also indicated that synovial osteochondromatosis may recur in patients with extensive involvement who are treated with synovectomy alone without dislocation of the hip; however, surgical complications are more likely to occur in patients managed with anterior dislocation of the hip and synovectomy.
LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.
ORIGINAL ABSTRACT CITATION: “Operative Treatment of Primary Synovial Osteochondromatosis of the Hip” (2006;88: 2456-64).
Primary synovial osteochondromatosis of the hip is a relatively uncommon benign metaplastic disorder of the synovium characterized by formation of osteochondral bodies in the synovial cavity1,2. If the condition is left untreated, mechanical damage to the articular cartilage from the multiple intra-articular loose bodies can lead to degenerative arthritis of the hip. Late complications such as secondary hip subluxation or pathologic fracture of the femoral neck may follow3-5. Therefore, surgical débridement of the loose bodies and hypertrophied synovium is generally accepted as the optimal treatment for this condition, and such débridement can be performed through an open or arthroscopic surgical approach6-11. With advances in arthroscopic techniques, there has been growing interest in the arthroscopic treatment of this condition, but arthroscopic débridement can be a technically demanding procedure with potential complications, such as neurovascular injury or iatrogenic damage to the labrum or articular cartilage12,13. Moreover, open surgery remains the preferred method when even the most modern arthroscopic techniques cannot adequately address all pathologic lesions, such as when there is extra-articular spread of the disease14. Here we describe our surgical technique of open synovectomy and removal of loose bodies, combined with or without an anterior dislocation of the hip, for the treatment of primary synovial osteochondromatosis of the hip, with a focus on the pitfalls associated with this procedure and the technical details that can help minimize the risk of surgical complications.
All operations are performed through an anterolateral approach according to the method described by Soni15 for routine total hip replacement, with detachment of the anterior one-third of the gluteus medius muscle and the gluteus minimus tendon from the greater trochanter. However, for the purpose of complete débridement of the joint, an additional circumferential capsulectomy combined with the release of the iliopsoas tendon is needed to allow for adequate mobilization of the femoral head.
A room equipped with ultraviolet lights and vertical air-flow is used, and 1 g of cefazolin is administered intravenously for antibiotic prophylaxis one hour before the skin incision. After the induction of spinal anesthesia, the patient is placed in the lateral decubitus position on a standard operating room table with the pelvis stabilized in a neutral position and aligned with the symphysis pubis and sacrum by means of padded supports (Fig. 1). A straight skin incision is made in a superior-to-inferior direction over the center of the greater trochanter and then extended superiorly and inferiorly (Fig. 2). This incision varies from 10 to 15 cm in length, depending on the size of the greater trochanter. Subcutaneous flaps are raised anteriorly and posteriorly to expose the gluteal fascia and the tensor fasciae latae, which is incised in a straight midlateral line along the length of the skin incision to allow an option to perform both anterior and posterior arthrotomies. This provides wide exposure of the greater trochanter in the center of the wound, with the gluteus medius muscle superiorly and the vastus lateralis muscle inferiorly (Fig. 3). The anterior one-third of the gluteus medius muscle is incised with an electrocautery from the anterior portion of the base of the greater trochanter and is retracted anteriorly to expose the gluteus minimus tendon, which is divided as a single flap from its attachment to the greater trochanter (Fig. 4). To provide a full exposure of the anterior capsule, one Hohmann retractor is placed over the superior aspect of the femoral neck, another is placed over the inferior aspect of the femoral neck, and a wide Hohmann retractor is placed between the anterior aspect of the acetabulum and the iliopsoas tendon (Fig. 5). The capsule is incised in an inverted “T” shape after the hip has been externally rotated to stretch the capsule (Fig. 6). The longitudinal limb of the capsulotomy is performed parallel to the axis of the femoral neck before it reaches the acetabular labrum, and the capsulotomy is continued transversely in line with the anterior intertrochanteric line. Care should be taken not to damage the underlying articular cartilage of the femoral head or acetabular labrum while inserting the Hohmann retractors or incising the capsule. For the purpose of complete débridement, the anterior capsule is then excised with use of a knife in an inside-out manner along the margin of the acetabular labrum, allowing for adequate mobilization of the femoral head (Fig. 7). The superolateral extension of the capsulectomy should stop before the piriformis tendon is reached to avoid injury to the terminal subsynovial branches of the medial femoral circumflex artery, and the inferomedial extension of the capsulectomy should stop anterior to the lesser trochanter to avoid injury to the deep branch of the medial femoral circumflex artery. Surgical débridement is carried out until all accessible loose bodies and proliferative synovial tissue have been removed from the joint. Removal of the tissue from the articular margins is best achieved with use of a small curet (Fig. 8). Osteophytes, when present, are removed from the femoral head or acetabular margin.
On the basis of the location and extent of disease as revealed on preoperative magnetic resonance imaging, we can further determine whether the areas involved by the disease can be débrided adequately with the femoral head left in place or if the procedure will require dislocation of the hip. We originally reported that, in patients who did not require hip dislocation, traction on the hip joint was performed with use of a corkscrew inserted into the greater trochanter in order to facilitate the débridement of any residual loose bodies and proliferative synovial tissue in the acetabular fossa. Currently, however, we apply lateral traction on the femoral neck with a bone hook to leave the greater trochanter inviolate. Surgical débridement through an additional small posterior capsulotomy is performed in hips with posterior loose bodies and proliferative synovial tissue that cannot be débrided through an anterolateral capsulectomy. In cases requiring a surgical hip dislocation because of extensive extra-articular extension of the disease, the iliopsoas tendon is released from its attachment to the lesser trochanter (Fig. 9) and an additional circumferential capsulectomy next to the margin of the labrum is performed to allow adequate mobilization of the femoral head. Electrocautery is used to transect the posteromedial tendinous portion of the iliopsoas muscle, leaving the anterior muscular portion intact. The femoral head is then subluxated in the lateral direction with use of a bone hook (Fig. 10), and the hip is dislocated anteriorly by flexion, adduction, and external rotation of the thigh (Fig. 11). Complete dislocation of the femoral head is achieved once the round ligament has been transected (Fig. 12).
Visualization of the entire acetabulum is facilitated by placing a right-angle Hohmann retractor over the posterior wall of the acetabulum to retract the femoral head posteriorly (Fig. 13). When performing the synovectomy with a surgical dislocation of the hip, the retinacular vessels on the posterolateral surface of the femoral neck should be identified, and it is of paramount importance to carefully preserve these vessels throughout the procedure. Surgical débridement of loose bodies and proliferative synovial tissue can be performed through a trochanteric osteotomy16, but we prefer to perform the procedure without doing an osteotomy because of the risk of complications related to trochanteric fixation, such as breakage of the fixation devices, bursitis, or failure to achieve union17. We originally reported that a surgical hip dislocation was reserved only for patients with extensive extra-articular extension of the disease because of the risk of complications associated with this procedure. Currently, however, we more often perform a dislocation in patients who have extensive disease involvement that includes the acetabular fossa, as we believe that an adequate capsulectomy combined with the release of the iliopsoas tendon may provide sufficient space between the pelvis and femur to allow a safe anterior dislocation of the femoral head.
After copious pressurized irrigation to flush out any undetected loose bodies, the joint is scrutinized to ensure that it is free of disease (Fig. 14). The femoral head is then relocated, and the gluteus minimus tendon and the gluteus medius muscle are repaired into their original attachments to the base of the greater trochanter with number-1 Vicryl sutures (polyglactin; Ethicon, Somerville, New Jersey). The iliotibial band and the gluteal fascia are closed carefully in a routine manner, and the wound is closed after inserting a suction drain.
All of the patients receive antibiotic prophylaxis with parenteral cefazolin (1 g every eight hours) for forty-eight hours, and a standard protocol of low-molecular-weight heparin is used selectively as thromboembolism prophylaxis in patients who have known risk factors for deep venous thrombosis. No adjuvant chemical or radiation synovectomy is indicated for this condition. The patient is encouraged to perform range-of-motion exercises of the hip and the knee on the first postoperative day. The patient is allowed to stand on the second postoperative day and to progress to partial weight-bearing with crutches as tolerated. Full weight-bearing is allowed after four weeks postoperatively.
Open synovectomy of the hip with removal of loose bodies is indicated for all patients who have a diagnosis of primary synovial osteochondromatosis and the absence of substantial arthritic change18,19. Magnetic resonance imaging is useful for the early detection of this condition, especially when no radiopaque bodies are evident on the plain radiographs20. An awareness of the findings relative to the location and extent of disease as revealed on the preoperative magnetic resonance images can help in determining whether adequate débridement can be accomplished with the femoral head left in place or if surgical dislocation of the hip will be required (Figs. 15-A through 15-D).
This procedure is not recommended for hips with severe osteoarthritic changes secondary to synovial osteochondromatosis, although, for such hips, the procedure may be combined with joint reconstructive surgery, such as total hip arthroplasty or resurfacing arthroplasty of the hip.
The skin and fascial incisions must be centered over the greater trochanter to allow the option to perform both anterior and posterior arthrotomy.
To avoid injury to the underlying articular cartilage of the femoral head or acetabular labrum, the capsulotomy should be performed in an inside-out manner with use of a knife after the hip has been externally rotated to stretch the capsule. Additionally, care should be taken not to damage the underlying articular cartilage or labrum when inserting the Hohmann retractors.
A thorough understanding of the anatomy of the medial femoral circumflex artery as delineated in the cadaveric injection study by Gautier et al.21 is of paramount importance for safe performance of this procedure without increasing the risk of osteonecrosis of the femoral head. If the superolateral capsular excision extends beyond the piriformis tendon, the terminal subsynovial branches of the medial femoral circumflex artery are at risk for injury. If the inferomedial capsular excision extends beyond the lesser trochanter, the deep branch of the medial femoral circumflex artery is at risk for injury. Most importantly, when performing the synovectomy with surgical dislocation of the hip, the retinacular vessels on the posterolateral surface of the femoral neck should be identified, and extreme care must be taken not to damage these vessels throughout the procedure.
A forceful femoral head dislocation maneuver can lead to an avulsion fracture of the lesser trochanter of the femur. Therefore, an additional circumferential capsulectomy with release of the iliopsoas tendon from its attachment to the lesser trochanter is required to allow for adequate mobilization of the femoral head, especially for patients with a very muscular thigh.
As the femoral neurovascular bundle lies in close proximity to the iliopsoas tendon and is at risk for traction injury during the surgical procedure, an excessive force or prolonged traction should be avoided to minimize the risk of femoral nerve injury, especially when this procedure is performed in hips with extensive extra-articular involvement of the disease deep to the iliopsoas tendon.
Failure to remove all of the proliferative synovial tissues, especially those located in the acetabular fossa, may result in a recurrence of the disease.
Copious pressurized irrigation needs to be performed repeatedly to flush out any undetected loose bodies.
Since the original article was published, there have been no substantial changes to the surgical technique except for the use of a bone hook rather than a corkscrew inserted into the greater trochanter during the performance of lateral traction of the femoral neck for improved acetabular visualization.
Originally, we reserved surgical hip dislocation only for patients with extensive extra-articular extension of the disease because of the risk of complications associated with this procedure. Currently, the indication for surgical hip dislocation has been extended to include patients who have extensive disease involvement that includes the acetabular fossa, as we believe that adequate capsulectomy combined with the release of the iliopsoas tendon may provide sufficient space between the pelvis and femur to allow a safe anterior dislocation of the femoral head.
In our series, surgical dislocation of the hip has been associated with an avulsion fracture of the lesser trochanter of the femur in one patient, a transient neurapraxia of the femoral nerve in another patient, and osteonecrosis of the femoral head six months postoperatively in a third patient. That male patient had undergone extensive débridement of the joint with anterior dislocation of the hip because of extra-articular extension of the disease, and a total hip arthroplasty was performed two years after the index operation. After experiencing this complication, we have performed the lateral and medial extensions of the capsular excision more strictly in order to avoid injury to the posterior vasculature of the femoral neck, which is a major supplier of blood to the femoral head; thereafter, we have had no additional cases of osteonecrosis of the femoral head.
The original scientific article in which the surgical technique was presented was published in JBJS Vol. 88-A, pp. 2456-64, November 2006
DISCLOSURE: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.
Investigation performed at Sungkyunkwan University School of Medicine, Samsung Medical Center, Seoul, South Korea
- Copyright © 2007 by The Journal of Bone and Joint Surgery, Incorporated