Reconstruction Cases Hip dysplasia

A 52-year-old postmenopausal female presents with progressive hip pain. She points to the pain in “C-clamp” distribution around the hip, mostly localized in her groin. She likes to run, but has not been able to do so over the last year. She describes start-up thigh pain and pain with putting her shoes on, getting in and out of cars, and deep flexion. The primary care physician was concerned with the possibility of femoroacetabular impingement and obtained an MRI that shows cartilage thinning and focal defects, as well as degenerative labral tear. A radiograph is also obtained (Fig. 7–5). The patient asks about her labral tear and the possibility of repair. Her pain persists despite anti-inflammatory medication, physical therapy, and activity modification.

 

 

Figure 7–5

 

When discussing the options for management, based on available data, the best intervention would be:

1. Observation

2. Hip arthroscopy with labral repair

3. HemiCAP partial arthroplasty

4. Hip resurfacing

5. Total hip arthroplasty

 

Discussion

The correct answer is (E). In the setting of ongoing pain despite nonsurgical treatment measures, total hip arthroplasty is indicated. Hip arthroscopy for debridement and labral repair is very successful in addressing isolated labral tears in younger patients but in the setting of arthritis the results are limited. HemiCAP partial arthroplasty is possible in a patient with a focal posttraumatic osteochondral defect or AVN but not in generalized arthritis. This patient does not fit the indications for hip resurfacing.

The Tonnis angle is a usual measurement used in the setting of acetabular dysplasia. This is measured by evaluating the angle created by:

1. A vertical line and the line connecting the center of femoral head to edge of acetabulum

2. A line along the ileum and another line along the acetabular roof

3. A horizontal line and the line along the acetabular roof

4. A horizontal line and the line from the teardrop to the acetabular edge

5. A line along the femoral axis and the line from the center of the femoral head to the center of knee

Discussion

The correct answer is (C). The angle of the sourcil was defined by Tonnis in the setting of dysplasia, with measurements greater than 10 to 12 being concerning. Other authors will also use the acetabular edge angle, the alpha angle, and acetabular angle of sharp.

The Crowe classification of acetabular dysplasia measures:

1. The degree of arthritis in dysplastic acetabuli

2. The amount of migration of the femoral head

3. The degree of lateralization of the femoral head

4. The amount of deformity of the femoral head

5. The degree of deformity of the acetabulum

 

Discussion

The correct answer is (B). Crowe classification quantifies the superior migration of the femoral head with respect to the true acetabulum. This is calculated by dividing the distance from the inferior tear drop to the inferomedial head–neck junction by femoral head size as a percentage of proximal migration of the femoral head.

Crowe I: less than 50% subluxation Crowe II: 50% to 75% subluxation

Crowe III: 75% to 100% subluxation

Crowe IV: More than 100% superior migration

In contrast, the Tonnis classification evaluates the severity of arthritic changes: Tonnis 0: No signs of degenerative joint disease

Tonnis I: Increased sclerosis and slight narrowing of joint space, normal femoral head

Tonnis II: Cysts, moderate narrowing, and femoral head deformity Tonnis III: Cysts, severe narrowing, and severe femoral head deformity

The patient then inquires about treatment options other than joint replacement. You state that a pelvic osteotomy is an option, but she is not a candidate because of her:

1. Advanced arthritis

2. Young age

3. Good range of motion

4. Skeletal maturity

5. Female gender

 

Discussion

The correct answer is (A). The goal of an osteotomy is to reestablish normal hip biomechanics and delay degenerative change progression and the need for arthroplasty. Periacetabular osteotomies are possible in:

. Younger patient

. Minimal arthritis

. Good preoperative range of motion

. Skeletally mature

. With dysplasia

 

Advanced dysplasia with significant superior migration of the femoral head requires work to bring the cup into its anatomic position. Lengthening of more than 4 cm is sometimes required which puts the sciatic nerve at high risk for traction neurapraxia. To avoid that, the surgeon can:

1. Use increased offset components to lateralize the hip

2. Perform an extended trochanteric osteotomy and advance the abductors

3. Use modular femoral components which allow surgeon to dial version appropriately

4. Perform a subtrochanteric osteotomy and shortening

5. Perform a neurolysis at the time of surgery

 

Discussion

The correct answer is (D). The risk of sciatic nerve palsy in hip dysplasia is 10 times the risk in a typical total hip arthroplasty and can top 15%. Even though several techniques are used in dysplastic hip, more than 4 cm of lengthening has a high risk of complications and should be considered for a femoral osteotomy and shortening. Depending on the case, some surgeons will also choose to maintain a

superior position of the acetabulum, which is not ideal but acceptable.

Increased offset and modular femoral components are helpful in increasing stability, improving the overall version and decrease risk of dislocation. An extended trochanteric osteotomy is sometimes necessary to address the contracted abductors.

 

Helpful Tip:

Hip dysplasia is a complex problem which may lead to severe degenerative joint disease requiring arthroplasty. In young patients, a periacetabular or femoral osteotomy is an option in the absence of degenerative changes and arthritis. Once arthritic changes and loss of cartilage has occurred, the results of osteotomy are significantly worse, with arthroplasty being the only option that would allow reproducible outcomes. Nevertheless, options for acetabular bone loss and femoral version correction should be available, including augments, and modular stems.

 

Objectives: Did you learn...?

 

 

Diagnose dysplasia based on x-rays and geometric measurements? Classify dysplasia based on Crowe or other classification?

 

Understand the associated complications possible after addressing dysplasia?