s

 

 

 

DEFINITION

Hip cartilage injuries are common and have been reported to be as high as 50% of all intra-articular hip pathology in a series of athletes.5

Focal cartilage defects in the hip present a challenge to the surgeon, although cartilage repair and joint preservation procedures have improved as methods of controlling progression to symptomatic arthritis. Total hip arthroplasty (THA) remains a viable option.

Treatment of hip cartilage injuries is especially important in young patients, a population in which THA should be avoided as long as possible due to lower THA survival rates.11

 

 

ANATOMY

 

The articular surfaces of the hip include the femoral head and acetabulum. The femoral head is deeply recessed in the acetabulum, making surgical access difficult.

 

The articular cartilage of the hip joint is thickest ventrolaterally and becomes thinner in a concentric gradient toward the fovea of the femoral head and the acetabular fossa.19

 

The hip joint is surrounded anteriorly by the capsular, iliofemoral, and pubofemoral ligaments and posteriorly by the ischiofemoral ligament.

 

The labrum forms a C-shaped circumferential border around the acetabulum, attached to the transverse acetabular ligament posteriorly and anteriorly. It extends contact over the femoral head, maintains intraarticular negative pressure, and serves to augment and protect the articular cartilage.

 

PATHOGENESIS

 

Possible causes of chondral injury to the hip include trauma, femoroacetabular impingement, synovial disorders, instability, osteonecrosis, osteochondritis dissecans, osteoarthritis, slipped capital femoral epiphysis, and rheumatoid arthritis.16

 

Acute traumatic cartilage injury to the femoral head or acetabulum in the young athlete is often caused by a lateral impact injury, with impact loading over the greater trochanter.18

 

Chondral injury is associated with labral pathology. McCarthy et al20 showed that 73% of patients with fraying or torn labrum had chondral damage.

 

Femoroacetabular impingement is one of the most common causes of hip chondral injury. Cam impingement leads to anterosuperior acetabular cartilage delamination without associated labral injury. Pincer impingement causes a contrecoup cartilage injury on the posteroinferior acetabulum with labral damage and ossification.

Both pathologies commonly exist concurrently.4

 

NATURAL HISTORY

 

Focal cartilage lesions increase the risk of progression to symptomatic osteoarthritis, especially for untreated defects larger than 2 cm without stable shoulders.2

 

Untreated cartilage injuries may precipitate the need for THA (FIG 1A).

 

PATIENT HISTORY AND PHYSICAL FINDINGS

 

The history and physical exam are used to determine whether the source of pain is intra-articular or extra-articular.

 

Patients display the C-sign to describe deep interior hip pain. Intra-articular injury typically does not present with pain on palpation.

 

There is no specific test for chondral injuries of the hip, although the flexion internal rotation (FIR), log roll test, and scour test are suggestive of intra-articular pathology.

 

The scour test: With the patient supine, the hip is rotated and knee fully flexed. Any clicking, catching, or other associated mechanical symptoms should be noted.

 

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

Plain radiographs are the hallmark of assessing hip pathology, but their use is limited in detecting chondral defects.

 

 

Magnetic resonance imaging (MRI) is the gold standard in detecting cartilage injuries of the hip (FIG 2). Noncontrast, cartilage-specific MRI sequencing has been proven effective, with strong agreement to arthroscopic findings. Mintz et al21 demonstrated 92% and 86% agreement of MRI and arthroscopic findings

for femoral articular cartilage defects in 92 patients with two readers. Acetabular cartilage defects showed

88% and 85% agreement between MRI and arthroscopic assessment.

 

 

Potter and Chong le26 also described the effectiveness of cartilage-specific MRI pulse sequences without contrast injection.

 

Magnetic resonance arthrography (MRA) may provide a more accurate assessment of chondral injury, with a contrast injection to outline the defect, although results have been less reliable than MRI. In addition, the contrast injection makes this a more invasive modality than MRI.

 

Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) enables assessment of glycosaminoglycan

content and can thus detect deteriorating changes in cartilage. Cunningham et al8 showed that lower scores on the dGEMRIC index effectively predicted failure of periacetabular osteotomy.

 

Multidetector computed tomography arthrography (MDCTA) is another modality used to detect cartilage defects, but recent studies have shown conflicting levels of diagnostic accuracy.6,23,24

 

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FIG 1 • A. Arthroscopic image of a right hip showing an unstable cartilage flap on the acetabulum. B. Arthroscopic image showing the microfracture awl technique. C. Arthroscopic image after microfracture showing bleeding bone.

 

 

Ultrasound is a new option to diagnose hip injuries and can be used for diagnostic injections.

 

DIFFERENTIAL DIAGNOSIS

 

Non-hip

 

 

Referred pain from lower back, sacroiliac joint, abdominal wall, gastrointestinal tract, genitourinary tract

 

 

 

FIG 2 • Sagittal MRI using coronal inversion recovery and fast spin echo axial sequences showing an osteochondral lesion in the weight-bearing portion of the right femoral head.

 

 

Hip

 

 

Extra-articular

 

 

 

Abductor, adductor, or rectus femoris tear Piriformis syndrome

 

 

Hamstring syndrome Trochanteric bursitis

 

Athletic pubalgia/osteitis pubis

 

 

Snapping from the iliopsoas or iliotibial band Intra-articular

 

 

 

Labral tear Avascular necrosis Loose bodies

NONOPERATIVE MANAGEMENT

 

The first line of nonoperative treatment for cartilage injuries includes rest, physical therapy, nonsteroidal anti-inflammatory drugs, and intra-articular injections. Surgical treatment is indicated if hip pain persists.

 

SURGICAL MANAGEMENT

 

There exist five surgical treatment options for cartilage injuries of the hip. These include débridement, direct suture repair, microfracture, osteochondral autograft transplantation (OATS), and autologous chondrocyte implantation or matrixinduced autologous chondrocyte implantation (ACI/MACI).

 

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OATS and ACI are more commonly done as open procedures, whereas débridement, repair, and microfracture are conducted arthroscopically.

 

 

 

 

FIG 3 • Flowchart showing how the surgical procedure is chosen based on location and depth of defect as well as the surgeon's experience with arthroscopic or open techniques.

 

 

The surgical treatment of choice depends on patient age, acuity of injury, location and depth of defect, and surgeon's experience with arthroscopic or open techniques (FIG 3).

 

Injuries in non-weight-bearing regions are indicated for débridement or microfracture for larger, full-thickness defects.

 

Direct cartilage repair is emerging as an alternative to microfracture for transitional zone full-thickness delaminations of the acetabulum.

 

Cartilage injuries in weight-bearing regions of the hip, such as the suprafovial femoral head or central acetabulum, are treated with microfracture, OATS, or ACI/MACI. Some authors30 have suggested that microfracture is associated with inferior outcomes for defects larger than 400 mm2.

 

Contraindications for any of the cartilage procedures include unwillingness or inability to complete the

rehabilitation protocol as well as kissing lesions, advanced arthritis, and infection.

 

Preoperative Planning

 

Plain radiographs are obtained to detect bony abnormalities, such as femoroacetabular impingement or acetabular dysplasia.

 

 

MRI/MRA is obtained to detect any associated soft tissue pathologies. Ultrasound-guided injections may be done to confirm intraarticular injuries.

 

For both arthroscopic and open procedures, the entire hip joint is inspected and any labral pathology is addressed and treated as well as any loose bodies removed from the joint space.

 

Arthroscopically, the anterolateral portal is used to evaluate the anterior labrum, acetabular fossa, ligamentum teres, and fovea capitis.

 

Two normal variants of the acetabular fossa may appear similar to cartilage defects: the stellate crease, located superiorly, and the physeal scar, which can be anterior or posterior.

 

The arthroscope is then moved to the anterior portal to inspect the posterior aspects of the hip joint and the posterior recess.

 

Positioning

 

Arthroscopic procedures can be performed with the patient in either the supine or lateral position and can use two or three portals depending on the size and location of injury. Anterolateral and midanterior portals are used, occasionally with a posterolateral portal (FIG 4).

 

Arthroscopic procedures should use a fracture table with a well-padded perineal post to prevent injury to the pudendal nerve. A foot stirrup should be used to place 25 to 50 pounds of traction on the limb with the goal of 7 to 15 mm of joint distraction, as confirmed by the C-arm.

 

Open procedures use the surgical hip dislocation, with the patient in the lateral position, using a trochanteric flip osteotomy.10

Approach

 

Arthroscopic approach is done according to the safe zone for hip arthroscopy.27

 

For arthroscopic procedures, the anterolateral portal is placed 1 to 2 cm superior and 1 to 2 cm anterior to the anterosuperior part of the greater trochanter. This portal

 

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should be the first one established and should be placed using fluoroscopic guidance in order to ensure proper placement and avoidance of injury to the articular surfaces or neurovascular bundle.18

 

 

 

FIG 4 • Arthroscopic positioning/approach.

 

 

The midanterior portal should be the next to be established and should be at the intersection of the vertical line below the anterior superior iliac spine and the horizontal line from the superior surface of the greater trochanter. Care must be taken because placement of this portal involves the greatest risk to the lateral

femoral cutaneous nerve, in addition to the lateral femoral circumflex artery.18

 

The posterolateral portal, if used, is located 2 to 3 cm posterior to the superior surface of the greater trochanter, at the same level as the midanterior portal. Placement of this portal presents risk of injury to the

sciatic nerve.18

 

Open procedures use the Ganz method of surgical hip dislocation to access the femoral head and acetabulum

while preserving the blood supply and minimizing the risk of avascular necrosis.10 With the patient in the lateral decubitus position, a Kocher-Langenbeck incision is used and the leg is then internally rotated. The next incision is from the posterosuperior edge of the greater trochanter to the posterior border of the ridge of vastus lateralis. The trochanteric osteotomy can then be performed in line with this incision, with a maximal thickness of 1.5 cm and can be a single or step cut. In order to protect the medial femoral circumflex artery (MFCA), the osteotomy should start posteriorly behind the insertion of the gluteus medius tendon. The greater trochanteric fragment with vastus lateralis can then be moved anteriorly after releasing its posterior border, and the leg is flexed and externally rotated. The piriformis is maintained on the stable trochanter. The inferior border of the gluteus minimus is then separated from the piriformis and capsule, preserving the inferior gluteal artery and MFCA. The sciatic nerve passes inferior to the piriformis and can be identified and protected. The

osteotomy frame can then be mobilized anteriorly and superiorly, exposing the capsule. An anterolateral incision along the femoral neck preserves the deep branch of the MFCA, and then an anteroinferior incision is made. The main branch of the MFCA lies superior and posterior to the lesser trochanter, so the capsulotomy must remain anterior to the lesser trochanter. After extending the incisions, the hip can be dislocated by flexing and externally rotating the leg, which is brought in front or anterior on the operating table.

 

TECHNIQUES

• Arthroscopic Débridement

   

  Flexible heat probes, straight and curved shavers, and angled curettes are used to remove unstable cartilage flaps and leave a well-shouldered lesion.

   

  It is crucial to avoid excessive débridement, preserving as much healthy cartilage and labrum as possible (TECH FIG 1).

   

   

   

  TECH FIG 1 • Intraoperative arthroscopic débridement of a right hip through the midanterior portal with the shaver positioned through the anterolateral portal.

• Direct Suture Repair

   

  As an alternative to débridement, suture anchor or meniscal repair devices can be used to directly repair loose cartilage flaps.

   

  The hip joint is inspected and assessed. Microfracture is performed underneath the delaminated cartilage defect, with care taken not to detach the flap.

   

  A suture passer device is used to pass an absorbable monofilament suture through the flap.

• Microfracture

   

  The hip joint is thoroughly inspected and the chondral defect assessed. All unstable cartilage is débrided from the exposed bone, with care taken to maintain a well-shouldered lesion and expose the subchondral bone (TECH FIG 2A).

   

  The calcified cartilage layer is removed using curettes.

   

  Thirty-, 70-, and 90-degree arthroscopic awls are then used to make multiple perpendicular holes (microfractures) in the subchondral plate, making as many holes as possible while leaving 3 to 4 mm between them. Also, a curved drill technique can be done (FIG 1B, TECH FIG 2B).

   

  Holes should be 2 to 4 mm in depth so that upon reduction of irrigation pressure, fat droplets and bleeding can be observed and adequate penetration confirmed (FIG 1C, TECH FIG 2C).

   

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  TECH FIG 2 • A. Arthroscopic image of a right hip showing a full-thickness femoral head lesion. B. Arthroscopic image showing the microfracture awl technique. C. Arthroscopic image after microfracture showing bleeding bone.

• Osteochondral Autograft Transplantation

   

  OATS is an open procedure using surgical hip dislocation.

   

  Osteochondral plugs may be harvested from the ipsilateral knee, typically the medial or lateral parts of the trochlea. Alternatively, the inferior non-weight-bearing portions of the femoral head22,29 or anterior femoral head-neck junction3 may be used as donor sites.

   

  Once plugs are harvested, tunnels are drilled at the recipient site. Tunnels are made shallower than the length of the plugs in order to preserve the curve of the femoral head.

   

  Cancellous bone is used to fill any gaps, and the donor tunnels are filled with plugs harvested form the recipient site.

   

  A fresh allograft may also be used instead of an autograft.

   

  The hip is reduced, the arthrotomy closed, and the trochanteric flip fixed with screws (TECH FIG 3).

   

   

   

  TECH FIG 3 • Intraoperative OATS.

• Autologous Chondrocyte Implantation/Matrix-Induced Autologous Chondrocyte Implantation

 

There are several generations of the ACI procedure, the more recent versions of which use implantable matrices in which chondrocytes are grown. These procedures are typically performed on each acetabulum and femoral head and can be done open or arthroscopically (TECH FIG 4).

 

For ACI on the femoral head, Akimau et al1 describe a procedure in which a collagen membrane is fixed over the femoral head and chondrocytes are injected into the membrane.

 

During the first procedure, a full-depth biopsy of articular cartilage is taken and cultured in lab.

 

Three weeks later, after surgical hip dislocation, the lesion is débrided to expose healthy, bleeding bone.

 

 

 

 

TECH FIG 4 • Arthroscopic view of the transplanted membrane covering the acetabular chondral defect during an autologous chondrocyte implantation procedure. (Reprinted from Fontana A, Bistolfi A, Crova M, et al. Arthroscopic treatment of hip chondral defects: autologous chondrocyte transplantation versus simple debridement—a pilot study. Arthroscopy 2012;28[3]:322-329, with permission from Elsevier.)

 

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Two collagen patches are sutured together and, once conformed to the femoral head, held in place using a purse string of polydioxanone around the femoral neck.

The edges of the collagen patches are sealed and chondrocytes are injected under the patch from two injection points.

The MACI procedure uses a three-dimensional scaffold that can be implanted arthroscopically, as described by Fontana et al.9

With the patient in lateral decubitus position, the defect is assessed arthroscopically and a biopsy of healthy cartilage is taken.

The chondrocytes are then cultured on a two-component gel polymer scaffold. They are cultured for 3 to 5 weeks on a monolayer, reaching about 12 million cells. These cells are then incubated over the membrane for an additional 2 to 6 weeks to facilitate three-dimensional growth.

At the second arthroscopic procedure, the defect is débrided to stable edges and prepared for scaffold implantation. The scaffold membrane is cut to fit the débrided region and then rolled into a tube for insertion through the cannula.

The scaffold is inserted, unrolled in the joint space, and positioned into the débrided defect. This step should be conducted without arthroscopic fluid in order to facilitate proper positioning.

Traction is then released, five extension and rotation movements are performed, and traction is reapplied to assess if the implant position is preserved.

 

PEARLS AND PITFALLS
	Débridement ▪ Surgeons must avoid excessive overdébridement, leaving as much healthy cartilage as possible.     Direct repair ▪ Absorbable sutures, suture anchors, or meniscal repair devices have all been used. Care must be taken when leaving prominent material in the joint.     Microfracture ▪ This can be done with traditional awls or powered curved drills.     OATS ▪ Both autograft and allograft tissue may be used depending on the size of the lesion. Care must be taken to get the appropriate contour correct.     ACI/MACI ▪ Both ACI/MACI can be done depending on the size of the lesion and the approach used. Care must be taken to achieve the appropriate fixation with each technique.

 

 

POSTOPERATIVE CARE

 

After arthroscopic procedures, patients should be partial weight bearing for 3 to 6 weeks, with increased weight bearing as tolerated. After microfracture, complete return to sports is not recommended until strength, functional agility, and range of motion have returned, approximately 4 to 6 months postoperatively. A

continuous passive motion machine should be used throughout the early recovery period.7

 

Open procedures require at least 6 weeks of 30% to 50% partial weight bearing followed by increased weight bearing as tolerated. Complete return to sports may not be advisable for up to 1 year postoperatively.

 

 

OUTCOMES

Direct suture repair has been described in limited case reports. Sekiya et al28 reported the use of direct suture repair for a full-thickness acetabular cartilage delamination. The patient returned to sports 7 months postoperatively with Harris hip score (HHS) of 96 and Hip Outcome Score Activities of Daily Living subscale of 93 at over 2-year follow-up.

Microfracture has been shown to provide better outcomes than débridement and nearly complete fill of the cartilage defect.

Haviv et al15 treated 29 patients with microfracture for grades II and III acetabular lesions less than 300

mm2 and 166 patients (170 hips) with débridement. At 22 months follow-up, the microfracture patients showed an improvement in nonarthritic hip score (NAHS) from 70.0 to 90.2—significantly greater improvement than the débridement patients, whose NAHS improved from 67.6 to 80.8.

Philippon et al25 performed microfracture on 9 patients with full-thickness acetabular cartilage defects and reported 91% mean fill at 20-month follow-up.

Karthikeyan et al17 performed microfracture on 20 patients with full-thickness acetabular cartilage defects and reported 93% mean fill at 17-month follow-up.

OATS has been used with good results for large lesions on the central acetabulum and suprafovial

femoral head. Girard et al12 reported results of OATS on 10 patients with mean defect size of 4.8 cm2 on the femoral head using grafts from the most inferior, non-weight-bearing portion of the femoral head. At 6-month follow-up, all patients showed well-incorporated plugs with intact overlying cartilage and normal curvature of the femoral head. All functional scores showed improvement at 29.2 months follow-up: the mean Postel Merle d'Aubigné score improved from 10.5 to 15.5, mean HHS improved from 52.8 to 79.5, mean Oxford Hip Score decreased (demonstrating functional improvement) from 34.5 to 19.2, Devane activity scale increased from 2.1 to 3.25, University of California, Los Angeles (UCLA) activity score increased from 3.7 to 5.8, and global range of motion increased from 175.4 to 210.7.

Nam et al22, Hart et al,14 and Bastian et al3 each published OATS case studies with excellent clinical results.

MACI has significantly outperformed débridement for acetabular lesions. Fontana et al9 compared débridement to MACI for cartilage defects in 30 patients with a mean size

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of 2.6 cm2. Débridement resulted in an improved HHS from 46 preoperatively to 59.1 at 6-month follow-

 

up and 56.3 at 5-year follow-up, with improved pain score and walking distance. MACI provided a significantly greater improvement in HHS, from 48.3 to 82.6 at 6-month follow-up and 87.4 at 5-year follow-up. MACI also resulted in significantly greater improvements in pain score. Three of the 15 MACI patients had unsatisfactory results and a postoperative HHS of 74.8, although these defects were all located on the femoral head, defects for which the authors suggest that scaffolds with inherent rigidity should not be used.

Akimau et al1 reported the use of ACI using a collagen membrane for osteonecrosis of the femoral head after traumatic injury. The HHS improved from 52 preoperatively to 76 at 12-month follow-up. Full-depth biopsy at 15 months showed a 2-mm thick layer of cartilage that was well integrated with the underlying bone.

Numerous studies have investigated the various cartilage restoration procedures in the knee, and no single procedure has provided superior clinical results.13,31

In the hip, THA remains the salvage procedure for all joint preservation and repair techniques. Further research is required to determine which procedures provide the best clinical results and most effectively prevent or delay the need for THA.

 

COMPLICATIONS

These procedures are associated with typical complications arising from arthroscopic and open procedures in the hip.

A common complication associated with débridement is excessive resection and subsequent progression of osteoarthritis.

Failure of microfracture may result due to insufficient fill from inadequate surgical technique and subchondral penetration.

Osteochondral autografts may result in donor site morbidity, plugs that are too proud or too recessed, and chondrocyte death upon impaction.

Osteochondral allografts eliminate donor site morbidity but may result in viral and bacterial disease transmission, inflammatory reactions, and host rejection of allograft.

ACI may exhibit graft hypertrophy, although more recent surgical techniques reduce this risk.

 

 

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