Open Repair and Arthroscopic Follow-Up of Severely Delaminated Femoral Head Cartilage Associated with Traumatic Obturator Fracture-Dislocation of the Hip

Case Report

A 16-year-old boy, who had undergone unsuccessful closed reduction at another institution 6 hours previously, presented to our emergency room after a motorcycle accident. The patient reported left hip pain and an inability to straighten his left thigh. Blood pressure and vital signs were essentially normal, as were systemic examination findings. Physical examination demonstrated that his left hip was in flexion, abduction, and external rotation. Limb sensation was intact, dorsalis pedis pulse was normal, and he was able to actively flex and extend his left foot. Anteroposterior radiography and computed tomography (CT) of the pelvis revealed an obturator dislocation of the hip with a large fracture fragment, originating from the femoral head, attached in the acetabulum (Figure ).

Figure 1:. AP Radiograph (A) and 3-Dimensional CT Scan (B) of Obturator Dislocation of the Left Hip with a Large Fracture Fragment (arrow) Originating from the Anterosuperior Aspect of the Femoral Head.

Emergent surgery was performed 6 hours after presentation using an anterolateral approach ⁷ in the lateral decubitus position (Figure ). This approach allowed access to the structures impeding reduction, including the rectus femoris and iliopsoas muscles, and torn joint capsules. After releasing these interposing tissues, the hip was able to be reduced. The hip was then redislocated anteriorly through the operative window to scrutinize the femoral head and fix the femoral head fragment (Figure ). The articular cartilage of the femoral head was found to be severely delaminated and to have peeled away from the head in some areas (Figures ). The large anterosuperior femoral head fragment, held in the ligamentum teres of the acetabulum, was released and fixed under direct vision to the dislocated femoral head with countersunk Acutrak screws (Acumed Inc, Beaverton, Oregon) (Figure ). Delaminated and detached articular cartilage were then reattached to underlying subchondral bone using suture anchors (Mini-Revo; Linvatec Inc, Largo, Florida) and multiple absorbable sutures (Vicryl Plus; Ethicon Inc, Somerville, New Jersey) (Figure ).

Figure 2:. The Patient Was Placed in the Lateral Position with Two Pelvic Supports (A). The Hip Was Dislocated Anteriorly by Flexion, Adduction, and External Rotation of the Thigh (B). Intraoperative Photographs Showing Severely Delaminated Femoral Head Articular Cartilage, Which Had Peeled off in Some Areas (arrow) (C, D).

Figure 3:. Intraoperative Photograph Showing a Large Bony Fragment Fixed to the Anterosuperior Portion of the Femoral Head with Headless Screws (A). Delaminated, Detached Articular Cartilages Were Reattached to Underlying Subchondral Bone Using Suture Anchors and Multiple Absorbable Sutures (B).

The patient was kept nonweight bearing for 6 weeks postoperatively and was allowed to resume full weight bearing gradually. He returned to normal activities of daily living at 14 weeks. No wound-healing disturbance, infection, or nerve lesion occurred. At 9 months postoperatively, arthroscopic examination showed complete healing of the fracture and cartilage lesions (Figure ), and at 12-month follow-up, no clinical or radiographic evidence of arthritis or osteonecrosis was evident (Figure ). He had no pain or limp, and achieved an excellent result according to Epstein’s clinical evaluation criteria. ¹

Figure 4:. Nine-Month Postoperative Arthroscopic Photograph of the Femoral Head Showing Complete Healing of the Fracture and Repaired Cartilage.

Figure 5:. Twelve-Month Postoperative AP Radiograph of the Left Hip Showing a Normal Joint Space with Mild Flattening of the Superolateral Aspect of the Femoral Head (arrow).

Discussion

Obturator hip dislocation is a rare injury that usually results from high-energy trauma in young adults. Impacted fractures of the femoral head have been reported in 35% to 55% of patients after anterior dislocation. ^3–5 Few cases of complete or indentation femoral neck fracture after anterior hip dislocation have been reported in the literature. ^8–10 However, obturator hip dislocation associated with a large femoral head fracture is extremely rare, ⁶ and to our knowledge, no obturator hip dislocation associated with a large femoral head fragment and severe delamination of articular cartilage has previously been described.

Many aspects of the treatment of femoral head fractures associated with traumatic anterior hip dislocation are disagreed upon. Epstein and Wiss ¹ recommended that all traumatic anterior dislocations of the hip must be treated as surgical emergencies, and that multiple attempts at closed reduction be avoided because of the danger of developing avascular necrosis of the femoral head or fracture of the femoral neck. Furthermore, the anatomical reduction of anterior hip dislocation associated with a displaced femoral head or neck fracture is difficult by closed reduction.

Various surgical approaches have been advocated for open reduction of an irreducible anterior fracture-dislocation of the hip, although the anterior approach has commonly been used in this situation. ^1,6,11 Recently, a trochanteric flip osteotomy, as described by Ganz et al, ¹² was also used to treat anterior fracture-dislocation of the hip. ^10,13 In the present case, an anterolateral approach ⁷ was used in the lateral decubitus position, as this provided direct access to the structures impeding reduction, which included the rectus femoris and iliopsoas muscles and torn joint capsules. This approach also allowed the hip to be easily redislocated anteriorly through the operation window, which allowed the femoral head to be scrutinized and fracture fixation and cartilage repair to be performed. In addition, we prefer to perform this procedure without osteotomy, because of the risk of complications related to trochanteric fixation, such as breakage of fixation devices, bursitis, or union failure. ¹⁴

Prosthetic replacement is an excellent treatment option for older patients with irreducible fracture-dislocation of the hip and for patients with neglected obturator hip dislocation, ¹⁵ but it is not ideal for younger patients. Impacted femoral head fractures associated with obturator hip dislocation are usually treated nonoperatively or by removal of small osteochondral fragments. However, a large fracture fragment cephalad to the fovea must be fixed rigidly, because this area is in contact with the articular cartilage of the acetabulum and is involved in weight bearing.

Richards and Howe ⁶ first reported open reduction and internal fixation of a displaced femoral head fragment associated with obturator fracture-dislocation of the hip. In their case, the patient had no damage to the articular cartilage of the femoral head, and the fractured fragment was fixed with 2 malleolar screws. However, in the present case, irreducible obturator dislocation of the hip was associated with a large femoral head fragment and severe delamination of articular cartilage. After open reduction of the hip joint using an anterolateral approach, the large femoral head fragment was completely released from the ligamentum teres and fixed to the dislocated femoral head with headless screws, and severely delaminated cartilages were repaired with suture anchors and absorbable sutures. This approach was chosen because we believe that internal fixation of femoral head fractures should achieve rigid fixation, preferably with compression between the fracture fragment and the remainder of the femoral head. Today, numerous implants, such as countersunk lag screws, headless screws, and bioabsorbable pins, are available for the treatment of femoral head fractures. ¹⁶

We believe that all injured cartilages, including smaller fragments, must be fixed because hip articular cartilage does not regenerate in adults. Furthermore, articular cartilage defects of the femoral head are often associated with worsening symptoms and early degenerative osteoarthritis. ¹⁷ The reconstruction of injured cartilage is of greater importance in young patients. In the present case, arthroscopic follow-up examination at 9 months postoperatively demonstrated complete healing of the fracture and cartilage lesions, and at the subsequent 12-month follow-up, there was no clinical or radiographic evidence of arthritis or osteonecrosis. To our knowledge, no previous report exists on arthroscopic follow-up of a repaired femoral head cartilage in patient with an anterior fracture-dislocation of the hip.