Hip Arthroscopy for Synovial Chondromatosis: Tips and Tricks

Abstract

Hip arthroscopy is an important diagnostic and therapeutic tool in the management of synovial chondromatosis. Removal of osteochondral fragments (OCFs) from the central and peripheral compartments is crucial for the relief of mechanical symptoms and subsequent joint destruction. Direct access to the central compartment is often limited because of the ball-and-socket morphology and limitation of traction. We present our surgical technique for removing OCFs and a new method for the removal of a large loose body using a nitinol stone retrieval basket. The technique facilitates removal of difficult-to-access fragments from the central compartment. Moreover, this technique allows removal of far-medial OCFs from the peripheral compartment.

Advances in both surgical technique and instrumentation have allowed the evolution of hip surgery from an open procedure to an arthroscopic procedure and have increased the complexity of conditions that can be treated in the central and peripheral compartments. Loose body removal is a common indication for hip arthroscopy. Often, it is a straightforward procedure; however, in the case of multiple loose bodies as in synovial chondromatosis (SC), removal of particles may be challenging and time-consuming. SC of the hip is a rare condition of unknown etiology characterized by the metaplastic formation of intra-articular cartilaginous nodules of the synovium. These nodules can detach and become loose bodies within the joint, which may undergo secondary calcification and ossification. Loose bodies tend to aggregate in the fossa and the labrocapsular recesses of the central compartment.¹ SC is generally a primary condition, but it may be associated with osteoarthritis. Hip arthroscopy is commonly used for loose body removal in the surgical treatment of SC.² Arthroscopic removal of loose bodies with synovectomy is advantageous because it offers less perioperative morbidity than the open surgical approach. Mastery of basic hip arthroscopy portals and technique is crucial. Loose bodies at the central compartment can be removed manually with a grasper or shaver or can be suctioned out of the joint through a telescoping cannula. However, in some cases retrieval of large osteochondral fragments from the central compartment is challenging with the standard arthroscopic tools because of the ball-and-socket hip anatomy and limitations of hip distraction. We present some techniques to facilitate the arthroscopic treatment of SC in general and introduce the nitinol stone retrieval basket as an enabling instrument for removal of large inaccessible loose bodies in particular (Tables 1 and 2).

Table 1.

Key Points in Addressing SC

Central compartment

1. Ensure adequate distraction for cannula access to the central compartment.

2. Remove all loose OCFs from the central compartment.

3. Perform synovectomy around the ligamentum teres.

4. Remove metaplastic bumps at the acetabular fossa.

5. Correct pincer lesions and repair the labrum.

6. Address any cartilage defect on the acetabular and femoral sides.

Peripheral compartment

1. Remove all loose OCFs from the peripheral compartment.

2. Perform synovectomy.

3. Remove metaplastic bone from the head-neck junction.

4. Obtain a motion study under direct arthroscopic viewing to ensure adequacy of head-neck resection.

5. Repair the capsule.

OCFs, osteochondral fragments.

Table 2.

Pearls for Removal of Loose Bodies

1. Use adequate distraction to allow instrument manipulation.

2. Use a cannula to facilitate removal of multiple loose bodies smaller than 5 mm.

3. Use a grasper for larger loose bodies.

4. Release bodies from surrounding soft-tissue or bony attachments before removal or use a burr for piecemeal removal.

5. Use a stone retrieval basket for large, far-medial bodies.

Surgical Technique

Preoperative Planning

Preoperative planning is essential to address all pathologies associated with SC. The location and size of loose osteochondral fragments at the central and peripheral compartments are noted on both true anteroposterior pelvic and cross-table lateral radiographs,³ as well as computed tomography or magnetic resonance imaging scans. Metaplastic bone occlusion of the acetabular fossa, as well as any coexistent cam and pincer femoroacetabular impingement, is assessed. Associated labral tears and cartilage lesions are identified on magnetic resonance angiography scans. Labral repair and microfracture options should be discussed with the patient.

Surgical Procedure

Hip arthroscopy was performed with the patient under general anesthesia in the supine position on a traction table. The operative hip was placed in 10° of hip flexion, 10° of abduction, and 20° of internal rotation. Intraoperative fluoroscopic imaging was then set up to precisely match the preoperative planning. Under hip distraction, the anterolateral portal was established with fluoroscopic guidance and the modified anterior portal was established with subsequent arthroscopic guidance. Capsulotomy between the 2 portals was carried out using either a hooked radiofrequency probe or an arthroscopic blade (VAPR or Mitek Sports Medicine Hip Straight Blade; DePuy Mitek, Raynham, MA) to facilitate instrument maneuverability. A thorough diagnostic evaluation of the hip was performed with a 70° arthroscope.

Central Compartment

Removal of free osteochondral bodies located in the central compartment was carried out under suction using a 5.5-mm arthroscopic cannula and then the outer sleeve of a 5.5-mm-long abrader burr (Smith & Nephew, Andover, MA) (Fig 1). The latter has the advantage of an oblique tip facilitating evacuation of multiple free bodies narrower than 5 mm while providing extra length (Fig 2). Most of the loose bodies were efficiently removed. For larger loose bodies, an arthroscopic grasper was used. Some large loose bodies were unreachable because of medial displacement beyond the femoral head even after the addition of a posterolateral portal. At this point, our scrub nurse suggested to try to use a nitinol stone retrieval basket (Boston Scientific, Marlborough, MA) originally designed for removal of ureteral stones. The device was inserted into a cannulated changing rod and was introduced into the joint through the anterolateral portal. The rod enabled control of the direction of the basket device toward the loose body. As the tip of the basket approached the desired location, the internal basket was advanced to securely snare the loose body (Fig 3). The changing rod with the basket and captured fragment were retracted from the hip over a slotted cannula (Smith & Nephew) (Video 1). The procedure was repeated to remove the residual loose bodies. Acetabular osteoplasty and labral repair, chondroplasty of unstable cartilage, and microfracture of a femoral head chondral lesion were also performed in this patient.

Fig 1.

Outer sleeve of the 5.5-mm burr facilitating evacuation of multiple free bodies narrower than 5 mm (A) from the central compartment through the anterolateral portal and (B) from the peripheral compartment through the modified anterior portal. (C, capsule; FB, free body.)

Fig 2.

A cannula can facilitate removal of free bodies smaller than 5 mm. (A) A 5.5-mm cannula (a); the outer sleeve of a 5.5-mm-long abrader burr (b); and a changing rod inserted into a suction tube, which allows the tip of the soft tube to be directed to the desired intra-articular location (c). (B) Multiple free bodies smaller than 5 mm removed by cannulas.

Fig 3.

The nitinol stone retrieval basket securely snares the loose body.

Peripheral Compartment

The traction was released, and the arthroscope was inserted into the peripheral compartment through the anterolateral portal. Loose bodies were removed, and synovectomy with straight and curved full-radius resectors was completed. A far-medial large osteochondral body was successfully removed with this same technique. Video 1 highlights the key technical steps including the arthroscopic suction technique (through a cannula and through an arthroscopic burr sheath) and removal of large loose bodies from challenging locations using the stone retrieval basket forceps.

The patient was instructed not to bear weight for 6 weeks because of the aforementioned microfracture chondroplasty. Early range-of-motion exercises were encouraged to prevent soft-tissue adhesions and promote early recovery. Passive motion was first restored, followed by active motion and then strength.

Discussion

SC of the hip joint is a benign yet locally aggressive synovial proliferative disorder traditionally treated with open surgery. Surgical management of SC attempts to address all pathologies associated with this disease: loose bodies, synovitis, labral tear, focal cartilage defect, and bony impingement due to osteochondral deposits at the femoral head-neck junction and at the fovea. As arthroscopy of the peripheral compartment became more popular, the treatment of aggressive synovial pathologies with arthroscopy became an option. Arthroscopy has several advantages over open surgery. It offers excellent visualization of both the central and peripheral compartments and allows tissue biopsy and subtotal synovectomy, leading to symptomatic improvement and potential hip preservation. Despite remarkable improvements in arthroscopic techniques to access and instrument the central and peripheral compartments, certain technical limitations exist. Examples are the inability to distract the hip, severe pincer deformity, and cases with incomplete access to far-medial and posterior pathologies.

The diagnosis and initiation of treatment for primary SC of the hip are often delayed because the initial radiographic findings are often nonspecific or negative and the first symptoms are mild and nonspecific.⁴ Popping and pseudo-locking are more common in advanced SC with larger loose bodies. Multiple intra-articular calcifications are the most common radiographic finding in SC. Joint space widening from a soft-tissue mass, osteochondral loose bodies, and structural changes, such as a thickened medial wall or newly formed osseous outer wall of the acetabulum, is also a frequent radiographic finding and can be identified sometimes even without specific abnormal findings.⁴ Treatment should be initiated as early as possible to relieve symptoms and prevent complications associated with disease progression. SC of the hip traditionally has been managed with an open surgical approach; however, this method is associated with significant surgical trauma, prolonged rehabilitation, and decreased range of motion. Arthroscopic synovectomy is advantageous because it offers sufficient visualization and clinical and functional improvement with less perioperative morbidity.⁵ Arthroscopic removal of the loose bodies is effective to alleviate symptoms and prevent secondary joint changes with or without synovectomy.²

Other techniques for using tools for loose body removal should be mentioned. Randelli et al.⁶ described the use of a flexible endotracheal catheter with applied suction; however, the small diameter often required piecemeal removal of individual loose bodies through a separate larger-bore cannula. The “vacuum cleaner” effect that we describe in this report is faster and more efficient for loose bodies smaller than 5 mm in diameter. A specialized curved grasper may be used to remove loose bodies; however, this device was not available, whereas many operating rooms and surgery centers may have an endoscopic urologic stone removal basket. Furthermore, the nitinol basket can ensnare a loose body that may float away from the closing grasper tip.

Hip arthroscopy for SC is a challenging and lengthy procedure. The use of the aforementioned techniques and tools facilitates the efficacious removal of loose bodies from the hip while the arthroscopic approach enables the treatment of coexisting hip impingement and/or intra-articular chondrolabral pathology in a less invasive manner.⁷ The use of the urologic stone removal basket has expanded applicability for arthroscopic large loose body removal beyond the setting of SC.

Supplementary Data

Video 1

Key technical steps including arthroscopic suction technique (through a cannula and through an arthroscopic burr sheath) and removal of large loose bodies from challenging locations using stone retrieval basket forceps.