[Follow up study of intertrochanteric valgus osteotomy with medial displacement in cases of primary protrusio acetabuly (author's transl)]

Minimum 2-Year Outcomes of Hip Arthroscopic Surgery in Patients With Acetabular Overcoverage and Profunda Acetabulae Compared With Matched Controls With Normal Acetabular Coverage

BACKGROUND

Advancements in instrumentation and techniques have extended the scope of hip arthroscopic surgery to treat complex osseous deformities that were previously best addressed with an open approach. Global pincer-type femoroacetabular impingement is an example of an abnormality requiring osseous correction with a technically challenging access point.

PURPOSE

To report on the patterns of clinical presentation and intra-articular derangements, radiological associations, and minimum 2-year outcomes after hip arthroscopic surgery in patients with a lateral center edge angle (LCEA) >40° and profunda acetabulae in comparison with matched controls with normal acetabular coverage.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Data were collected on all patients undergoing hip arthroscopic surgery during the study period from April 2008 to April 2013. All patients who had undergone hip arthroscopic surgery for symptomatic labral tears not responsive to a minimum of 3 months of physical therapy with both an LCEA >40° and profunda acetabulae, as defined by the ilioischial line lateral to the medial border of the teardrop, and without a history of hip surgery or hip conditions were included. This group was matched in a 1-to-1 ratio with a control group that had also undergone the arthroscopic management of symptomatic labral tears refractory to a minimum of 3 months of physical therapy with an LCEA between 25° and 40° according to age within 3 years, sex, body mass index category, Tönnis grade, labral treatment, and capsular treatment. Range of motion, impingement signs, and radiographic indices of coverage and version were recorded for each group. Four patient-reported outcome (PRO) scores, the visual analog scale (VAS) for pain, patient satisfaction, revision hip arthroscopic surgery, and conversion to total hip arthroplasty (THA) were also recorded.

RESULTS

Thirty-nine patients met the inclusion criteria for the study (overcoverage) group, of which 36 (92.3%) patients had a minimum 2-year follow-up; 215 patients satisfied the inclusion criteria for the control (normal coverage) group, of which 183 (85.1%) had a minimum 2-year follow-up. Thirty-six patients were matched in each group using the above criteria. There was no difference with respect to range of motion and impingement signs between the groups. The study group had significantly higher radiological markers of overcoverage but not retroversion compared with the control group. The study group had a significantly higher incidence of Seldes type 2 tears compared with the control group: 50.0% versus 19.4%, respectively ( P = .013). Both groups demonstrated significant improvements in the mean scores of all PROs, but the study group had a lower magnitude of improvement for all the PROs compared with the control group, with the modified Harris Hip Score (mHHS) achieving statistical significance: 13.5 versus 21.7 points, respectively ( P = .032). The study group had a significantly lower mean patient satisfaction score compared with the control group: 6.61 versus 7.91, respectively ( P = .019). The study group also had a significantly higher incidence of conversion to THA compared with the control group: 4 versus 0, respectively ( P = .040).

CONCLUSION

Hip arthroscopic surgery for the management of symptomatic labral tears in patients with combined overcoverage and coxa profunda is associated with improvements in patient outcomes and pain at a minimum 2-year follow-up. However, the degree of improvement is of lower magnitude compared with a matched cohort with normal coverage undergoing the arthroscopic management of symptomatic labral tears. While hips with lateral overcoverage combined with coxa profunda may have a smaller potential for improvement compared with hips with normal coverage, this type of osseous morphology is still repairable with arthroscopic treatment.

Hips With Protrusio Acetabuli Are at Increased Risk for Failure After Femoroacetabular Impingement Surgery: A 10-year Followup

BACKGROUND

Protrusio acetabuli is a rare anatomic pattern of the hip in which the femoral head protrudes into the true pelvis. The increased depth of the hip and the excessive size of the lunate surface typically lead to severe pincer-type femoroacetabular impingement (FAI); however, to our knowledge, there are no published mid- or long-term studies on results of circumferential acetabular rim trimming through a surgical hip dislocation for patients with this condition.

QUESTIONS/PURPOSES

(1) What is the 10-year survivorship of the hips treated with circumferential rim trimming through a surgical hip dislocation compared with a control group of hips that underwent surgery for pincer FAI but that did not have protrusio acetabuli? (2) What are the factors that were associated with a decreased likelihood of survivorship in those hips with the following endpoints: total hip arthroplasty, Merle d'Aubigné score of less than 15, and/or radiographic progression of osteoarthritis (OA)? (3) Does the radiographic pattern of degeneration differ between the two groups?

METHODS

We performed a case-control study comparing two groups: a protrusio group (32 patients [39 hips]) and a control group (66 patients [86 hips]). The control group consisted of hips treated with a surgical hip dislocation for pincer FAI and did not include hips with a positive protrusio sign or a lateral center-edge angle > 39°. The study group did not differ from the control group regarding the preoperative Tönnis OA score, age, and body mass index. However, the study group had more women, decreased mean height and weight, and lower preoperative Merle d'Aubigné-Postel scores, which were inherent differences at the time of first presentation. During the period in question, the indication for performing these procedures was a painfully restricted range of motion in flexion and internal rotation (positive impingement sign). The mean followup of the protrusio group (9 ± 5 years [range, 2-18 years]) did not differ from the control group (11 ± 1 years [range, 10-13 years], p = 0.109). At the respective minimum followup intervals in the underlying database from which cases and control subjects were drawn, followup was 100% for patients with protrusion who underwent FAI surgery and 97% for patients with FAI who underwent surgery for other anatomic patterns (three of 86 hips). We assessed the Merle d'Aubigné-Postel score, Harris hip score, WOMAC, and UCLA activity score at latest followup. A Kaplan-Meier survivorship analysis of the hip was calculated if any of the following endpoints for both groups occurred: conversion to total hip arthroplasty, a Merle d'Aubigné-Postel score < 15, and/or radiographic progression of OA. Differences in survivorship were analyzed using the log-rank test.

RESULTS

At 10-year followup, we found a decreased survivorship of the hip for the protrusio group (51% [95% confidence interval {CI}, 34%-67%]) compared with the control group (83% [95% CI, 75%-91%], p < 0.001) with one or more of the endpoints stated. We found four multivariate factors associated with a decreased likelihood of survival of the native hip according to the mentioned endpoints: body mass index > 25 kg/m(2) (adjusted hazard ratio, 6.4; 95% CI, 5.2-8.1; p = 0.009), a preoperative Tönnis OA score ≥ 1 (13.3; 95% CI, 11.8-14.9; p = 0.001), a postoperative lateral center-edge angle > 40° (4.2; 95% CI, 2.8-5.6; p = 0.042), and a postoperative posterior coverage > 56% (6.0; 95% CI, 4.3-7.6; p = 0.037). Preoperatively, joint space narrowing and osteophytes were more frequent posteroinferior (joint space narrowing 18% versus 2%, p = 0.008; osteophytes 21% versus 4%, p = 0.007), medial (joint space narrowing 33% versus 5%, p < 0.001) and  anterior (osteophytes 15% versus 1%, p = 0.004) in the protrusio compared with the control group. After correction in hips with protrusio, progression of joint space narrowing (from 6% to 45%, p = 0.001) and osteophyte formation (from 15% to 52%, p = 0.002) was most pronounced laterally.

CONCLUSIONS

At 10 years, in 51% of all hips undergoing open acetabular rim trimming for protrusio acetabuli, the hip can be preserved without further radiographic degeneration and a Merle d'Aubigné score > 15. Even with the lack of a control group with nonoperative treatment, isolated rim trimming may not entirely resolve the pathomorphology in protrusio hips given the clearly inferior results compared with surgical hip dislocation for FAI without severe overcoverage.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Techniques and Results for Open Hip Preservation

While hip arthroscopy grows in popularity, there are still many circumstances under which open hip preservation is the most appropriately indicated. This article specifically reviews open hip preservation procedures for a variety of hip conditions. Femoral acetabular impingement may be corrected using an open surgical hip dislocation. Acetabular dysplasia may be corrected using a periacetabular osteotomy. Acetabular protrusio may require surgical hip dislocation with rim trimming and a possible valgus intertrochanteric osteotomy. Legg-Calve-Perthes disease produces complex deformities that may be better served with osteotomies of the proximal femur and/or acetabulum. Chronic slipped capital femoral epiphysis may also benefit from a surgical hip dislocation and/or proximal femoral osteotomy.

Operative treatment of FAI: open hip preservation surgery

Femoroacetabular Impingement (FAI) is characterized by abnormal contact of the hip joint. Many etiologies cause this painful condition, which leads to early osteoarthritis. While hip arthroscopy has become the most prevalent way to surgically correct a hip, some presentations of FAI require open surgical hip preservation techniques to fully address the pathology at hand. Certain head neck deformities may require open surgical hip dislocation utilizing a trochanteric slide osteotomy. A retroverted acetabulum may require an open periacetabular osteotomy to gain anteversion and eliminate impingement in the hip joint. Acetabular protrusio may require surgical hip dislocation with rim trimming and a possible valgus intertrochanter osteotomy. The sequelae of Legg-Calvé-Perthes disease causes complex abnormalities about the hip joint, which may require open surgery to address both the intra-articular pathology and the extra-articular pathology. Osteotomies of the proximal femur and acetabulum may all be necessary to restore a hip back to normal morphology. Chronic slipped capital femoral epiphysis (SCFE) may also require open surgical hip dislocations and complex intertrochanter osteotomies to recreate normal morphology.

Protrusio acetabuli: new insights and experience with joint preservation

Protrusio acetabuli is identified on anteroposterior (AP) radiographs of the pelvis with an acetabular line projecting medial to the ilioischial line. We documented this radiographic sign and additional radiographic parameters in 19 patients (29 hips) with protrusio and compared the parameters to those of 29 older patients (29 hips) with advanced primary osteoarthritis (OA) but no protrusio and 12 younger patients (22 hips) with protrusio but no advanced OA. A negative acetabular roof angle and particularly large acetabular fossa were more apparent in younger patients; these hips suggest the destruction of a protrusio hip begins less in the medial joint area and more in the posteroinferior joint, and the mechanism is driven less by excessive medially directed forces but by a pincer impingement. While the indication for joint-preserving surgery currently consists primarily of a valgus femoral osteotomy based on AP radiographs and patient age, modern decision making also relies on cartilage evaluation and requires advanced surgical techniques. We conclude joint-preservation surgery must be tailored to the individual hip morphology.

Protrusio acetabuli: diagnosis and treatment

Idiopathic protrusio acetabuli is an uncommon disease process with both primary idiopathic and secondary forms. It is important to consider all etiologic possibilities before evaluating treatment options. Diagnosis is made on the basis of an anteroposterior radiograph of the pelvis that demonstrates a center-edge angle greater than 40 degrees and medialization of the medial wall of the acetabulum past the ilioischial line. For the skeletally immature patient, triradiate fusion (occasionally combined with intertrochanteric osteotomy) provides good results. For the young adult, valgus intertrochanteric proximal femoral osteotomy is recommended. In the older adult, this procedure may provide an acceptable result if there is minimal arthritis. For patients with more advanced arthritis, total hip arthroplasty with lateralization of the cup to a normal position provides a predictable long-term solution.