A 31-year-old woman with right hip pain

Issue: August 2016

ByMichael D. Stover, MD

ByDaniel B. Gibbs, MD

A 31-year-old woman presented to the office with 2 years of activity-related non-radiating right groin pain. The patient had a positive “C” sign and noted pain and an occasional limp with prolonged activity. She experienced most of the pain while using the elliptical or walking. She was also unable to run without pain and denied mechanical symptoms.

Her examination demonstrated a nonobese (BMI 27) healthy appearing 31-year-old woman with a normal gait. Her hip range of motion was symmetric with flexion to 95°, internal rotation to 20°, external rotation to 75° and 60° of abduction. She had joint irritability with terminal hip flexion, adduction and internal rotation (positive FADIR test) and was neurovascularly intact.

Radiographs and an MRI of the right hip (Figure 1 and Figure 2) were obtained.

Anteroposterior view (a), Dunn view (b) and false profile view (c) of the right hip and pelvis are shown.

What is your diagnosis?

Axial (a) and coronal (b) T2-MRI through the right hip show intrasubstance edema and degeneration of the hypertrophied labrum with no evidence of a detachment.

See answer on next page.

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Right hip dysplasia

The patient’s radiographs have the classic features of hip acetabular dysplasia, including decreased lateral center edge angle (LCEA = 15° [normal 25° to 40°]), increased acetabular index (AI=16° [0° less than normal less than 10°]), elevated extrusion index (35% [normal is less than 25%]) and a broken Shenton’s line.

Her anterior center edge angle is 17° (normal 25° to 50°), which suggested anterior undercoverage. She has a positive posterior wall sign with the center of her femoral head lateral her to her posterior wall, suggesting deficient posterior coverage. Radiographs also demonstrated a crossover sign, suggesting cranial retroversion of the acetabulum. The patient did not have an ischial spine sign, where a prominent ischial spine projects into the pelvis, which also may be present with acetabular retroversion. The radiographs demonstrated an elevated caput collum diaphysis angle (CCD angle= 142° [coxa valga greater than 135°]) and asphericity of her right femoral head (alpha angle 85° [normal less than 55°]). Her Tonnis Grade was 0, indicating no plain radiographic evidence of cartilage wear. These radiographic findings were consistent with global acetabular deficiency and coxa valga, with diminished concavity at the head neck junction (Figure 1).

Management

Her MRI revealed a hypertrophied labrum with some degeneration but no evidence of detachment (Figure 2). A diagnosis of right hip dysplasia was made based on history, physical examination and imaging. The patient had a diagnostic intra-articular hip injection which completely relieved her pain for a brief period. Operative and nonoperative management were discussed with the patient and she elected to proceed with a right periacetabular osteotomy (PAO).

Anteroposterior view (a) and false profile view (b) demonstrate an improved acetabular position, union of the pubis, ischium and ileum osteotomies with no evidence of hardware failure.

The Bernese PAO was performed with modifications described by Reinhold Ganz, MD. The acetabulum was moved into a more adducted, anteverted and medialized position during the procedure. An arthrotomy was performed following reorientation, and the labrum was evaluated. The labrum had some degeneration but no discrete detachment from the peripheral acetabular rim. Given the aspherecity of her femoral head, a femoral neck osteoplasty (FNO) was performed to maintain passive ROM of the hip without demonstrable impingement. Following the osteoplasty, the labrum remained in contact with the femoral head throughout range of motion and no instability of the labrum was observed.

This patient has a typical presentation of acetabular dysplasia. The dysplastic hip results in abnormal acetabular rim stress which can lead to degenerative labral changes and ultimately detachment of the labrum in varying degrees from the acetabular rim. Management of the acetabular deficiencies, as well as consideration of the femoral head, neck, version abnormalities and evaluation of labrum pathology, are all necessary in the treatment of this disease. Hip arthroscopy alone would not fully manage these deficiencies and this patient’s pathology.

Osteoarthritis (OA) of the hip is the end-stage for individuals with untreated hip dysplasia. In a study by Murphy and colleagues, a CEA less than 16°, extrusion index greater than 31% and an acetabular index greater that 15° were poor prognostic factors for individuals with untreated dysplasia. In fact, in untreated patients with all three of these findings, 100% of patients elected for hip replacement before age 65 years.

Discussion

Evaluating intermediate to long-term outcomes after a PAO for hip dysplasia, Matheney and colleagues found a 76% hip preservation rate at an average of 9 years. Approximately half of the 24% failures underwent conversion to THA and half continued to have significant hip pain. Steppacher and colleagues found a 60% preservation rate at 20 years. Worse results were seen in older patients (30 years or more), a higher preoperative grade of OA (grade II or higher), a higher postoperative extrusion index, a positive preoperative anterior impingement sign and in those with a worse patient-reported outcome score (measuring pain, mobility and ability to walk).

Nassif and colleagues examined hip arthroscopy with labral repair followed by PAO and open FNO and found no increased risk of complications in groups undergoing both procedures. They recommended FNO following reorientation in those patients with a femoral head-neck deformity and in those at risk for secondary femoroacetabular impingement. Still unanswered is whether all individuals with labral detachment should undergo either arthroscopic repair or open repair in the same surgical setting as the PAO.

At final follow-up, the patient was doing well with no hip pain. She was able to return pain-free to her activities, including running. Her range of motion was consistent with preoperative levels and she had no impingement signs on exam. Her final radiographs demonstrated improvement in lateral center edge angle (30°), acetabular index (0°), extrusion index (15%) and restoration of Shenton’s line (Figure 3).

References:
Clohisy J. J Bone Joint Surg Am. 2008;doi:10.2106/jbjs.h.00756.
Klaue K, et al. J Bone Joint Surg. 1991;73:423-429.
Matheney T, et al. J Bone Joint Surg Am. 2009;doi:10.2106/jbjs.g.00143.
Murphy SB, et al. J Bone Joint Surg Am. 1995;77: 985-989.
Nassif N, et al. J Bone Joint Surg Am. 2012;doi:10.2106/jbjs.k.01038.
Steppacher S, et al. Clin Orthop Relat Res. 2008;doi:10.1007/s11999-008-0242-3.

For more information:
Daniel B. Gibbs, MD; and Michael D. Stover, MD, can be reached at Northwestern University Feinberg School of Medicine, Department of Orthopaedic Surgery, 676 N. Saint Clair, Suite 1350, Chicago, IL 60611; Gibbs’ email: daniel.gibbs@northwestern.edu; Stover’s email: michael.stover@nm.org.

Disclosures: Gibbs and Stover report no relevant financial disclosures.