Synovial chondromatosis is a rare and benign proliferative disorder of the synovial lining.2 The etiology is unclear, but cells of the synovial lining are thought to undergo metaplasia forming cartilaginous and osteocartilaginous bodies in the capsule, including the retinacular layer.2,12 These bodies continue to be nourished by the synovial fluid and may grow to become sessile or pedunculated chondromas, or break off to form loose bodies.17,20
The hip is the second most common site of involvement after the knee.19,22 Patients usually present in the second to fifth decades of life with nonspecific clinical symptoms- typically dull, aching joint pain, catching, or locking sensations, or mild limitation of motion.12 The initial radio-graphic picture is often negative, with the characteristic juxtaarticular radiopacities not seen until much later in the disease process.11 Because of its insidious clinical presentation, there are usually long delays in accurate diagnosis and initiation of treatment.7,12 Treatment is based on the premise that the sessile or pedunculated chondromas and loose bodies damage the articular cartilage and intraarticular structures leading to secondary osteoarthrosis. Numerous authors agree that loose bodies should be removed from the joint,7,12,15,17,24 but there is disagreement whether synovectomy is necessary to prevent recurrence or progression.9,25
Managing hip chondromatosis is particularly difficult because complete hip access is restricted with open approaches7,9,15,17,24,25 or arthroscopy.13,23,30 Since 1993, the senior authors (RTT and RG) have treated eight patients with monoarticular synovial chondromatosis using a surgical hip dislocation with a trochanteric flip osteotomy which allows complete débridement of the joint with removal of loose bodies and a modified complete synovectomy (retinacular vessels are preserved).
We questioned whether complete débridement and modified complete synovectomy through this approach would be an effective treatment in preventing recurrence of synovial chondromatosis of the hip. We also wanted to establish any associations of osteoarthritis with synovial chondromatosis in this small series.
MATERIALS AND METHODS
We retrospectively reviewed eight patients who had débridement and synovectomy of the hip for treatment of monoarticular synovial chondromatosis. All patients were treated from 1993 to 2001 and had a minimum followup of 4 years (mean, 6.5 years; range, 4-10 years). There were four women and four men with a mean age of 37.6 years (range, 20-65 years) (Table 1). The right side was operated on in six patients and the left side in two patients. The mean duration of symptoms preoperatively averaged 2.6 years (range, 1-7 years). None of the patients had a positive family history of synovial chondromatosis. The typical presenting symptom in this group was groin pain associated with impairments in daily activities and mobility. Mobility was accompanied with locking and catching sensations of the involved hip and with limited active and passive range of motion in flexion and rotation. All patients required daily nonsteroidal antiinflammatory medication to relieve symptoms preoperatively. Six patients had no previous major injury or surgery. Two other patients had previous surgical treatments that failed. One (Patient 1) had three unsuccessful débridements, including two anterior arthrotomies without dislocation 4 and 13 years previously, and a subsequent arthroscopic débridement 1 year before surgical hip dislocation (Fig 1). Another patient (Patient 6) had a stiff hip in flexion with persistent or new chondromas after a failed arthroscopic débridement 1 year before surgical hip dislocation (Fig 2).
Standard anteroposterior and lateral radiographs of the hip were done preoperatively in all patients.27 Degeneration at the hip was assessed according to the method described by Tönnis.29 Hips with irregular subchondral sclerosis of the femoral head or acetabulum with mild loss of apparent joint space and minimum formation of osteophytes were classified as Grade 1; hips with small subchondral cysts in the femoral head or acetabulum with moderate loss of apparent joint space were classified as Grade 2; and hips with large cysts in the femoral head or acetabulum with severe or complete loss of the apparent joint space with or without collapse of the femoral head were classified as Grade 3.
Because the diagnosis of synovial chondromatosis is not always apparent on plain radiographs, the diagnosis was confirmed with magnetic resonance imaging (MRI), using the method described by Locher et al,14 in all patients who did not have recurrent disease. A typical finding of synovial chondromatosis on MRI is synovial thickening or proliferation surrounded by bright contrast material (gadolinium) on T1-weighted images. Peduncular or loose bodies with slight calcification are isointense or intermediate signal intense compared with muscle signal intensity on T1-weighted images. Lower signal intensity is seen in chondromas with higher calcification.
All surgeries were performed by the two senior authors (RTT and RG). The surgical approach used for complete débridement and modified total synovectomy involved a hip dislocation as described by Ganz et al.5 The patient was placed in the lateral decubitus position. Using a Gibson approach with a trochanteric flip, the hip was exposed anteriorly and dislocated in the same direction, while respecting the integrity of the external rotator muscles including the piriformis. This allowed full preservation of the main blood supply to the femoral head, the medial femoral circumflex artery.6,21,26 After performing a z-shaped capsulotomy, the hip was exposed and examined in detail. The surgical dislocation of the joint always provided a full 360° view of the femoral head and the acetabulum for débridement and synovectomy. Preservation of the synovial lining over the retinacular vessels prevents a complete synovectomy, and therefore we use the term modified complete synovectomy, as all the synovial lining is removed except in this location. The retinacular vessels are the terminal branches of the medial femoral circumflex artery and should be preserved to avoid avascular necrosis (AVN) of the femoral head. Intraoperatively, free and adherent chondromas were identified and recorded (Fig 3). Additionally, articular cartilage damages and alterations of the labral complex were located and recorded as a part of the medical report.
All specimens were examined histologically to confirm synovial chondromatosis. Under magnification (×10-100), syno-vial chondromatosis appeared as focal islands of disorganized hyaline cartilage metaplasia in the synovial lining. Pathologic examination showed aggressive cytologic features including enlarged chondrocytes, hypercellularity, and pleomorphic nuclei.
The intraoperative and histologic findings were summarized and classified according to Milgram19: (1) active intrasynovial disease only, with no loose bodies; (2) a transitional phase involving active intrasynovial proliferation and intraarticular loose bodies; and (3) multiple osteochondral bodies apparently caused by previously active, now quiescent intrasynovial disease (Table 2).
Postoperatively, patients received a second-generation cephalosporin for prophylaxis against infection for the first 48 hours, and low molecular heparin for deep vein thrombosis prophylaxis was administered subcutaneously for 8 weeks. For the first 8 weeks postoperatively, partial weightbearing with 5 kg and no active hip abduction were recommended to allow healing of the trochanteric osteotomy. Prophylaxis (indomethacin) against heterotopic ossification was not routinely used. The standard rehabilitation program starting 8 weeks postoperatively included a self-administered abductor training protocol. Bicycling and swimming also were recommended. After 10 to 12 weeks, the patients returned to their previous employment. At this time, nearly full functional recovery was obtained
Followup data were collected 8 weeks postoperatively and then continued annually by two independent observers (RS, DDRN).
Recurrence was confirmed or excluded by repeated MRI (Patients 2, 5, 6, 8) if clinically indicated, and by histologic examination of the retrieved synovial lining in patients who had reoperations. Recurrence was not excluded in two patients who were asymptomatic with perfect clinical scores.
Postoperative clinical function was evaluated according to the criteria of Merle d'Aubigné and Postel.18 For the Merle d'Aubigné and Postel score, a maximum of six points is given for each of three subgroups: pain level, walking status, and range of motion. A result is considered good or excellent when the total score is 15 to 18 points, fair when it is 12 to 14 points, and poor when it is less than 12 points.28 Postoperative radiographs were reviewed for progression of osteoarthritis29 in all patients. We used Tönnis grades to assess osteoarthritis.23
We used the Wilcoxon signed rank-sum test to compare pre-operative and postoperative clinical scores.
No patient had recurrence of disease at the latest followup. The six patients who retained their hips at a mean followup of 6.2 years had no recurrence as verified by MRI (four hips) or by excellent clinical outcome (two hips). The Merle D'Aubigné and Postel score improved (p = 0.01) in these six patients from a mean of 11.3 points (range, 8-13 points) preoperatively to 16.5 points (range, 15-18 points) at the latest followup. The main improvements in the Merle D'Aubigné and Postel score were in pain and walking ability. Two patients were pain free, one patient had occasional mild pain, two patients had mild pain with prolonged walking, and one patient had tolerable pain with limited vigorous activity (Table 2).
In six patients there was no progression in osteoarthritic stage, and all of these patients had Grade 0 or Grade 1 osteoarthritis preoperatively (Table 2). One patient (Patient 1) progressed from Grade 2 to Grade 3 and the other (Patient 3) progressed from Grade 1 to Grade 2. Both patients required a THA for progressive pain. Patient 3, however, had significant cartilage damage at the time of surgery which did not coincide with the given radiographic stage, which could account for the rapid progression of disease. Patient 1 had multiple previous surgeries (Fig 1) and had a THA 10 years after surgical dislocation. Patient 3 had severe cartilage damage at the time of initial surgical dislocation and had a THA 5 years later. Neither patient had evidence of recurrent disease on pathologic evaluation of the synovial membrane retrieved during THA.
Intraoperatively, all but one patient had extensive synovitis and loose bodies suggesting a transitional phase of synovial chondromatosis.19 This patient, (Patient 1) who had three previous surgeries, was most likely in the late phase.19 Acetabular cartilage damage was severe in two patients (Patients 1 and 3). All patients had labral lesions but only one had a partial labral resection (Patient 8). In five patients, circumferential adherent chondromas at the femoral head/neck junction were removed. In these patients, an acetabular cartilage-sided lesion, similar to those seen in patients with a Cam-type femoroacetabular impingement, was seen intraoperatively. Two patients had chondromatosis tissue partially interposed between acetabular and femoral cartilage which also could be responsible for the mild articular damage (Patients 2 and 6).
From the surgical standpoint, there were no complications, and specifically, no signs of AVN of the femoral head or trochanteric problems.
Our small series suggests that a complete débridement and modified total synovectomy through a surgical hip dislocation is effective in treating this rare condition. There were no recurrences, it provided and excellent clinical outcome, and it was associated with low surgical morbidity.
Synovial chondromatosis of the hip is rare. No surgeon treats a large number of patients with this problem. Therefore, a limitation of our study is the small number of patients from two tertiary-care centers that specifically treat hip problems. In addition, this study is limited by its retrospective nature and the lack of a control group.
The goal of treating synovial chondromatosis of the hip is to prevent recurrence and to delay progression of secondary joint damage. The reported rates of recurrence after surgical treatment for synovial chondromatosis range from 3.2%17 to 22.2%.30 The true rate of recurrence or residual disease is uncertain because of the difficulty in diagnosing recurrence or the lack of reporting its occurrence. We used MRI and intraoperative pathologic examinations to diagnose recurrences in our patients; these were not used in patients in previous studies. The recurrence rate in our patients was zero.
It is controversial whether synovectomy should be performed in addition to removing the loose bodies. Some authors have concluded that concurrent synovectomy does not improve results.9,25 This finding, however, must be interpreted cautiously, as other study populations included patients with knee and hip disorders, with patients with hip disorders being a minority in each study.9,19,25 All patients in our study had a modified complete synovectomy, and the results were excellent in patients with minimal osteoarthritic disease. Whether performing débridement alone without a synovectomy is a viable option cannot be concluded from this study, however it would seem intuitive that to prevent recurrence of disease, the diseased synovial lining should be removed. This is in accordance with two previous studies that also have shown better outcomes after synovectomy.17,24
The technique of loose body removal also is controversial with advocates for either open arthrotomy or hip arthroscopy. McIvor and King reported four patients with synovial chondromatosis of the hip treated by complete removal of loose bodies and subtotal excision of the synovial membrane combined with surgical dislocation, with good clinical outcomes in all four patients and no recurrences.17 Postel et al reviewed 32 cases of patients with synovial chondromatosis of the hip. Nine cases were discovered at the time of THA, 11 were discovered during removal of loose bodies only without synovectomy and without dislocation, and 12 were discovered during complete removal of loose bodies and subtotal synovectomy by dislocating the hip.24 Postel et al reported better results and no complications in patients treated by synovectomy and surgical hip dislocation. Our results compare favorably with results these studies, as there were no recurrences and no complications associated with the surgical approach. Other authors have reported removing synovial chondromatosis and performing a partial synovectomy with hip arthroscopy.10,13,16,23,30 These studies are limited to case reports or small series with poor followup. A well-designed arthroscopic study with sufficient power is lacking. The unavoidable drawback that plagues arthroscopy is the lack of sufficient observation, especially posteroinferiorly, to perform a thorough synovectomy and complete removal of loose bodies. In patients with previous surgery who have dense scar tissue and a contracted capsule, arthroscopic débridement incurs the risk of substantial damage to the cartilage, especially the retinacular vessels.
Two patients in our study had recurrence of disease after attempted arthroscopic débridement. Several techniques are available to the surgeon to access the hip for excision of loose bodies and partial synovectomy, including the posterior approach with tenotomy of the external rotators, use of a classic trochanteric osteotomy, and the anterolateral and direct lateral approaches. These, however, have compromised observation, risk of nonunion or migration of the trochanteric fragment, or AVN of the femoral head. We think surgical dislocation provides unmatched observation with no risk to femoral head vascularity, such that a thorough débridement can be performed.1,3,4,8 In addition, a modified complete synovectomy (sparing the synovial lining over the retinacular vessels) can be performed precisely. This approach, when used in this patient population, has minimal morbidity as has been reported when used for other conditions.5
Two patients in our study had progression of Tönnis osteoarthritis grade leading to THA. These patients had more severe arthritic changes seen intraoperatively. Patients with mild disease showed no progression. Because of the small study group, a direct association between progression of osteoarthritis and surgical intervention cannot be made. However we think that removal of all loose bodies, performance of a modified complete synovectomy, and excision of adherent circumferential chondromas that can lead to secondary femoroacetabular impingement could account for the lack of progression of osteoarthritis in hips with mild or no osteoarthritis.
The midterm results of this study suggest that open débridement with modified total synovectomy is an effective treatment that prevents recurrence of disease and provides substantial pain relief. Surgical hip dislocation allows safe and complete access to the joint for débridement and synovectomy with no added morbidity.
1. Dall D. Exposure of the hip by anterior osteotomy of the greater trochanter: a modified anterolateral approach. J Bone Joint Surg Br
2. Davis RI, Hamilton A, Biggart JD. Primary synovial chondromatosis: a clinicopathologic review and assessment of malignant potential. Hum Pathol
3. Epstein HC. Traumatic dislocations of the hip. Clin Orthop Relat Res
4. Epstein HC. Posterior fracture-dislocations of the hip; long-term follow-up. J Bone Joint Surg Am
5. Ganz R, Gill TJ, Gautier E, Ganz K, Krugel N, Berlemann U. Surgical dislocation of the adult hip a technique with full access to the femoral head and acetabulum without the risk of avascular necrosis. J Bone Joint Surg Br
6. Gautier E, Ganz K, Krugel N, Gill T, Ganz R. Anatomy of the medial femoral circumflex artery and its surgical implications. J Bone Joint Surg Br
7. Gilbert SR, Lachiewicz PF. Primary synovial osteochondromatosis of the hip: report of two cases with long-term follow-up after synovectomy and a review of the literature. Am J Orthop
. 1997;26: 555-560.
8. Hardinge K. The direct lateral approach to the hip. J Bone Joint Surg Br
9. Jeffreys TE. Synovial chondromatosis. J Bone Joint Surg Br
10. Kelly BT, Williams RJ3rd, Philippon MJ. Hip arthroscopy: current indications, treatment options, and management issues. Am J Sports Med
11. Kim SH, Hong SJ, Park JS, Cho JM, Kim EY, Ahn JM, Park YS. Idiopathic synovial osteochondromatosis of the hip: radiographic and MR appearances in 15 patients. Korean J Radiol
. 2002;3: 254-259.
12. Knoeller SM. Synovial osteochondromatosis of the hip joint: etiology, diagnostic investigation and therapy. Acta Orthop Belg
13. Krebs VE. The role of hip arthroscopy in the treatment of synovial disorders and loose bodies. Clin Orthop Relat Res
14. Locher S, Werlen S, Leunig M, Ganz R. MR-Arthrography with radial sequences for visualization of early hip pathology not visible on plain radiographs. Z Orthop Ihre Grenzgeb
15. Maurice H, Crone M, Watt I. Synovial chondromatosis. J Bone Joint Surg Br
16. McCarthy JC, Lee JA. Arthroscopic intervention in early hip disease. Clin Orthop Relat Res
17. McIvor RR, King D. Osteochondromatosis of the hip joint. J Bone Joint Surg Am
18. D'Aubigne RM, Postel M. Functional results of hip arthroplasty with acrylic prosthesis. J Bone Joint Surg Am
19. Milgram JW. Synovial osteochondromatosis: a histopathological study of thirty cases. J Bone Joint Surg Am
20. Murphy FP, Dahlin DC, Sullivan CR. Articular synovial chondromatosis. J Bone Joint Surg Am
21. Notzli HP, Siebenrock KA, Hempfing A, Ramseier LE, Ganz R. Perfusion of the femoral head during surgical dislocation of the hip: monitoring by laser Doppler flowmetry. J Bone Joint Surg Br
22. Ogilvie-Harris DJ, Saleh K. Generalized synovial chondromatosis of the knee: a comparison of removal of the loose bodies alone with arthroscopic synovectomy. Arthroscopy
23. Okada Y, Awaya G, Ikeda T, Tada H, Kamisato S, Futami T. Arthroscopic surgery for synovial chondromatosis of the hip. J Bone Joint Surg Br
24. Postel M, Courpied JP, Augouard LW. Synovial chondromatosis of the hip. Value of dislocation of the hip for complete removal of pathological synovial membranes. Rev Chir Orthop Reparatrice Appar Mot
25. Shpitzer T, Ganel A, Engelberg S. Surgery for synovial chondromatosis: 26 cases followed up for 6 years. Acta Orthop Scand
26. Siebenrock KA, Ganz R. Osteochondroma of the femoral neck. Clin Orthop Relat Res
27. Siebenrock KA, Kalbermatten DF, Ganz R. Effect of pelvic tilt on acetabular retroversion: a study of pelves from cadavers. Clin Orthop Relat Res
28. Streck W. Investigation of a hip patient in the private accident insurance. Prakt Orthop
29. Tonnis D. Congenital Dysplasia and Dislocations of the Hip in Children and Adults. Heidelberg, Germany: Springer; 1987.
30. Witwity T, Uhlmann RD, Fischer J. Arthroscopic management of chondromatosis of the hip joint. Arthroscopy