Arthroskopische Behandlung des femoroazetabulären Impingements

[Hip arthroscopy]

Hip arthroscopy represents an important component in the treatment of diseases of the hip joint and is nowadays an indispensible tool in modern hip-preserving surgery. This article provides a review of the basic technical principles, typical indications and complications of hip arthroscopy. Furthermore, current developments as well as possibilities and limitations of the arthroscopic technique are reviewed.

Surgical innovation and safety: femoroacetabular impingement and the IDEAL collaborative framework

Operative treatment of femoroacetabular impingement (FAI) is a relatively new, yet rapidly expanding surgical innovation. Although the practice of surgery is inherently innovative, there is no clear distinction between minor technical variation and true modification that warrants testing. This raises important questions about how new procedures should be evaluated before being broadly disseminated. The IDEAL Collaborative is a consortium that promotes safe and responsible translation of research into clinical practice. The collaborative has delineated the typical stages of evolution of new interventional technologies, and the type of study designs appropriate for each stage. This report examines the surgical treatment of FAI as a case study of the IDEAL framework and discusses both missed and future opportunities for critical assessment.

Three-dimensional kinetic simulation before and after rotational acetabular osteotomy

BACKGROUND

Some reports indicate that one of major causes of clinical failure after periacetabular osteotomy is development of secondary femoroacetabular impingement (FAI). To assess the impact of range of motion (ROM) on the increase in FAI following rotational acetabular osteotomy (RAO), we performed FAI simulations before and after RAO.

METHODS

We evaluated 12 hips that had undergone RAO (study group), and 12 normal hips (control group). The study group was evaluated before and after surgery. Morphological parameters were evaluated to assess acetabular coverage. The acetabular anteversion angle, anterior CE angle, alpha angle, and combined anteversion angle were also measured. Impingement simulations were performed using 3D-CT. The ROM which causes bone-to-bone impingement was evaluated in flexion (flex), abduction, external rotation at 0° flexion, and internal rotation at 90° flexion. The lesions caused by impingement were evaluated.

RESULTS

Radiographic measurements indicated improved postoperative acetabular coverage in the study group. The crossover sign was recognized pre- and postoperatively in every case in the study group and in no cases in the control group. In the simulation study, flexion, abduction, and internal rotation at 90° flexion decreased postoperatively. Impingement occurred within 45° internal rotation at 90° flexion in two preoperative and nine postoperative cases. The impingement lesions were anterosuperior of the acetabulum in all cases. There were correlations between anterior CE angle, CE angle, acetabular anteversion angle, and hip flexion angle. There were also correlations between the anterior CE angle, combined anteversion angle, and angle of internal rotation at 90° flexion.

CONCLUSIONS

In the postoperative simulation, there was a tendency to reduce the ROM in flexion, abduction, and internal rotation at 90° flexion due to impingement. Since there were more cases which caused impingement within 45° internal rotation at 90° flexion after RAO, we consider there is a potential for increased FAI after RAO.

Arthroscopic versus open cam resection in the treatment of femoroacetabular impingement

PURPOSE

The purpose of this study was to evaluate if osseous correction of the femoral neck achieved arthroscopically is comparable to that achieved by surgical dislocation.

METHODS

We retrospectively analyzed all patients who were treated with hip arthroscopy or surgical dislocation for cam or mixed type femoroacetabular impingement (FAI) in our institution between 2006 and 2009. Inclusion criteria were complete clinical and radiologic documentation with standardized radiographs. Group 1 consisted of 66 patients (49 female patients, mean age 33.8 years) treated with hip arthroscopy. Group 2 consisted of 135 patients (91 male patients, mean age 31.2 years) treated with surgical hip dislocation. We compared the preoperative and postoperative alpha and gamma angles, as well as the triangular index. Mean follow-up was 16.7 months (range, 2 to 79 months).

RESULTS

In group 1, the mean alpha angle improved from 60.7° preoperatively to 47.8° postoperatively (P < .001) and the mean gamma angle improved from 47.3° to 44.5° (P < .001). Over time, the preoperative mean alpha angle increased from 56.3° in 2006 to 67.5° in 2009, whereas the postoperative mean alpha angle decreased from 51.2° in 2006 to 47.5° in 2009. In group 2, the mean alpha angle improved from 75.3° preoperatively to 44.8° postoperatively (P < .001), and the mean gamma angle improved from 65.1° to 52.2° (P < .001). Arthroscopic revision of intra-articular adhesions was performed in 4 patients (6.1%) in group 1 and 16 patients (12%) in group 2. Three patients (2.2%) in group 2 underwent revision for nonunion of the greater trochanter.

CONCLUSIONS

Osseous correction of cam-type FAI with hip arthroscopy is comparable to the correction achieved by surgical hip dislocation. There is a significant learning curve for hip arthroscopy, with postoperative osseous correction showing improved results with increasing surgical experience.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Hip capsule dimensions in patients with femoroacetabular impingement: a pilot study

BACKGROUND

Joint-preserving hip surgery, either arthroscopic or open, increasingly is used for the treatment of symptomatic femoroacetabular impingement (FAI). As a consequence of surgery, thickening of the joint capsule and intraarticular adhesions between the labrum and joint capsule and between the femoral neck and the joint capsule have been observed. These alterations are believed to cause persistent pain and reduced range of motion. Because the diagnosis is made with MR arthrography, knowledge of the normal capsular anatomy and thickness on MRI in patients is important. To date there is no such information available.

QUESTIONS/PURPOSES

The purpose of this study was to establish thickness, length of the hip capsule, and the size of the perilabral recess in patients with FAI.

METHODS

We reviewed the preoperative MR arthrography of 30 patients (15 men) with clinical symptoms of FAI. We measured capsular thickness and made observations on the perilabral recess.

RESULTS

The joint capsule was thickest (6 mm) anterosuperiorly between 1 and 2 o'clock. The average length from the femoral head-neck junction to the femoral insertion of the capsule ranged from 19 to 33 mm. A perilabral recess was present circumferentially, even across the acetabular notch, where the labrum is supported by the transverse acetabular ligament. The shortest recess occurred superiorly.

CONCLUSIONS

Knowledge of the capsular anatomy in patients with FAI before surgery is important to judge the postoperative changes and to plan potential further therapy including arthroscopic treatment of intraarticular adhesions.

Influence of resection geometry on fracture risk in the treatment of femoroacetabular impingement: a finite element study

BACKGROUND

A fracture is the most serious complication of surgical resection of the femoral head-neck junction in the treatment of cam-type femoroacetabular impingement (FAI).

PURPOSE

To investigate the influence of resection length, width, and depth on postoperative fracture risk in activities of daily living.

STUDY DESIGN

Descriptive laboratory study.

METHODS

The femoral anatomy used for the finite element model was based upon a publicly available standardized model. For descriptive validation, the fracture location was compared with radiographs of patients who had suffered from a femoral neck fracture after surgical treatment of FAI in our institution. Additionally, a 2-part quantitative validation against previously published experimental data was performed. To simulate surgery, round resections were made in which length and width were varied at 10%, 20%, and 30%. The fracture loads were compared with published in vivo loads measured during activities of daily living with telemetric hip implants.

RESULTS

Validation showed that the model predicted fracture locations comparable with clinical cases and fracture loads within published experimental values. Femoral fracture loads were 325% more sensitive to resection deepening and 70% more sensitive to widening than lengthening.

CONCLUSION

Although resection depth is the most important determinant of bone resistance, it should be considered in combination with resection length and width. Even a resection depth as low as 10% may lead to a fracture in case of stumbling.

CLINICAL RELEVANCE

We show that for resection depths of 20% or less and resection length of less than 35% of the femoral neck, normal activities of daily living are safe. Resection widths typically achieved in practice did not induce fractures during activities of daily living. Patients who have undergone surgical resection should be counseled on how to try to avoid stumbling.

Hip arthroscopy after surgical hip dislocation: is predictive imaging possible?

PURPOSE

Our purpose was to study the sensitivity, specificity, and predictive values for hip adhesions, labral tears, and articular cartilage lesions in patients who had open treatment for femoroacetabular impingement, had persistent symptoms, and had both magnetic resonance arthrography (MRA) with radial slices and hip arthroscopy.

METHODS

Of 750 patients, 21 patients (6 male and 15 female patients; mean age, 28 years [range, 16 to 41 years]) with persistent groin pain after open osteochondroplasty and femoroacetabular impingement were included. The mean time between open osteochondroplasty and hip arthroscopy was 19 months (range, 4 to 79 months). At index surgery, patients had open osteochondroplasty of the femoral head-neck junction, as well as resection of the acetabular rim with reattachment of the labrum. All patients had preoperative MRA.

RESULTS

At hip arthroscopy, 1 tear of the labrum was verified on MRA. MRA showed in all patients adhesions between the neck of the femur and joint capsule, which were confirmed at arthroscopy and removed. Sensitivity of MRA for tears and adhesions was 100%; specificity, 100% and positive predictive value (PPV), 100%. For acetabular cartilage damage, sensitivity was 66.7%; specificity, 77.8%; and PPV, 63.6%. For femoral cartilage damage, sensitivity was 80%; specificity, 100%; and PPV, 20%. Postoperative alpha angles were significantly decreased. Of 21 patients, 3 had persisting groin pain.

DISCUSSION

Persistent groin pain after open osteochondroplasty of the hip could result from pathologic changes such as intra-articular adhesions with concomitant soft-tissue impingement. This pathology, as well as cartilage damage and labral tears, can be shown on MRA with radial slices.

CONCLUSIONS

Twenty-one patients with persistent groin pain after open osteochondroplasty of the hip had adhesions identified by MRA with radial slices. At hip arthroscopy, these adhesions were removed and 18 of 21 patients had relief of their symptoms.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

An algorithmic approach to surgical decision making in acetabular retroversion

The optimum treatment for the young adult patient with symptomatic femoroacetabular impingement due predominately to acetabular retroversion remains unknown. The retroversion deformity can be associated with a volumetrically deficient or sufficient acetabulum based on the adequacy of lateral and posterior coverage. We prospectively collected clinical data from 2001 to 2006 on 60 hips with symptomatic femoroacetabular impingement that had radiographic evidence of acetabular retroversion defined as a crossover sign on an adequate anteroposterior radiograph or retroversion on magnetic resonance imaging or computed tomography. Our treatment algorithm for acetabular retroversion used measurements of acetabular coverage (lateral center edge angle and the posterior wall sign) and condition of acetabular cartilage to direct treatment of acetabular retroversion. The algorithm directed the surgeon to perform a periacetabular osteotomy in 30 hips and a surgical dislocation and osteochondroplasty of the femoral head-neck junction and acetabular rim in 30 hips. Harris Hip Score improved from 52 to 90 in the hips treated with surgical dislocation and osteochondroplasty and 72 to 91 in the hips treated with periacetabular osteotomy, with an overall survivorship of 96% at 4 years. Patient follow-up averaged 46 months (range, 24-75 months). Elimination of the crossover sign and correction of the posterior wall sign occurred in >90% of all patients when present. The results indicate that hips with acetabular retroversion, deficient posterior and/or lateral acetabular coverage, and intact hyaline cartilage can be effectively treated with acetabular reorientation, while retroverted hips with anterior overcoverage but sufficient posterior coverage are effectively treated with osteochondroplasty of the acetabulum and proximal femur.

[Arthroscopic resection of the cam deformity of femoroacetabular impingement]

OBJECTIVE

Resection of the cam deformity of the femoral head-neck junction in order to avoid femoroacetabular impingement and the development of secondary damage to the anterolateral acetabular rim.

INDICATIONS

Femoroacetabular cam impingement. Initial femoroacetabular pincer impingement. Advanced femoroacetabular pincer impingement with degenerative tear of the labrum.

CONTRAINDICATIONS

Femoroacetabular pincer impingement with significant retroversion and intact acetabular labrum, coxa profunda or circumferential ossification of the labrum. Advanced osteoarthritis.

SURGICAL TECHNIQUE

Arthroscopy of the peripheral compartment via three portals with and without traction. The proximal anterolateral portal is used for the arthroscope, instrumentation is done via the anterior and classic anterolateral portal. After resection of the zona orbicularis and the inner parts of the iliofemoral ligament, the anterolateral cam deformity is resected without traction via the anterior portal. After distraction of the head from the acetabulum, the lateral and posterolateral cam deformity is trimmed via the classic anterolateral portal.

POSTOPERATIVE MANAGEMENT

Pain-controlled progression to full weight bearing over 1-4 weeks, continuous passive motion therapy and stationary bike for 6 weeks in order to avoid intraarticular adhesions.

RESULTS

From 2004 through early 2007, 72 hip arthroscopies were performed for femoroacetabular impingement. So far, 48 patients (25 men, 23 women, mean age 37 years [17-65 years]) were followed up. After a mean follow-up of 18 months, the WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) was significantly improved from 65 +/- 21 to 82 +/- 18 and the NAHS (Non Arthritic Hip Score) from 57 +/- 19 to 78 +/- 19.

COMPLICATIONS

two persistent branch lesions of the lateral femoral cutaneous nerve. One patient was surgically dislocated after 8 months for the treatment of a significant retroversion of the acetabulum; one patient underwent total hip arthroplasty after 1 year.

Arthroscopic treatment of femoroacetabular impingement of the hip: a new technique to access the joint

Femoroacetabular impingement has been established as an important cause of groin pain and limitation of range of motion in young, active patients and a possible cause for early osteoarthritis of the hip. Open surgery is a well-recognized approach for treatment and probably the standard for most surgeons, but recent reports regarding arthroscopic treatment procedures suggest comparable results. We present a technique that provides a way to securely penetrate the joint capsule and evaluate the clinical results of this technique in patients with femoroacetabular impingement. Between 2004 and 2007, we prospectively followed a cohort of 105 hips (88 patients; 60 males, 28 females) who underwent surgery for symptomatic cam or mixed femoroacetabular impingement. All patients were evaluated for the Nonarthritic Hip Score, clinical parameters, visual analog scale pain score, initial radiographic degenerative changes, and alpha angle. At a minimum followup of 1.3 years (average, 2.3 years; range, 1.3-4.1 years), all clinical outcome measures improved. The Nonarthritic Hip Score improved from 56.7 points (range, 15-92.5 points) to 84.6 points (range, 47.5-100 points). Nine patients (8.6%) underwent THA during followup. The outcome measures after arthroscopic therapy for femoroacetabular impingement seem comparable to those reported after open procedures.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

[Radiological diagnosis of femoroacetabular impingement]

Femoroacetabular impingements (FAI) are due to an anatomical disproportion between the proximal femur and the acetabulum which causes premature wear of the joint surfaces. An operation is often necessary in order to relieve symptoms such as limited movement and pain as well as to prevent or slow down the degenerative process. The result is dependent on the preoperative status of the joint with poor results for advanced arthritis of the hip joint. This explains the necessity for an accurate diagnosis in order to recognize early stages of damage to the joint. The diagnosis of FAI includes clinical examination, X-ray examination and magnetic resonance imaging (MRI). The standard X-radiological examination for FAI is carried out using two X-ray images, an anterior-posterior view of the pelvis and a lateral view of the proximal femur, such as the cross-table lateral or Lauenstein projections. It is necessary that positioning criteria are adhered to in order to avoid distortion artifacts. MRI permits an examination of the pelvis on three levels and should also include radial planned sequences for improved representation of peripheral structures, such as the labrum and peripheral cartilage. The use of contrast medium for a direct MR arthrogram has proved to be advantageous particularly for representation of labrum damage. The data with respect to cartilage imaging are still unclear. Further developments in technology, such as biochemical-sensitive MRI applications, will be able to improve the diagnosis of the pelvis in the near future.

Arthroscopically assisted anterior decompression for femoroacetabular impingement: technique and early clinical results

INTRODUCTION

In patients with symptomatic femoroacetabular impingement resection osteochondroplasty of the femoral head-neck junction may improve hip pain and range of motion. We evaluated the short-term treatment results of an arthroscopically assisted mini-open anterior approach to compare it with the results after surgical dislocation for FAI.

METHODS

The clinical and radiographic results of 33 patients were reviewed retrospectively 15 months after the surgery. Harris hip scores and plain radiographs were obtained preoperatively and at follow-up. Patient satisfaction with the treatment result was quantified with a Visual Analogous scale (VAS) ranging from 0 (very dissatisfied) to 10 (very satisfied).

RESULTS

The mean Harris hip score improved from 64 points preoperatively to 85 points at the time of follow-up (P < 0.001). Mean patient satisfaction on the VAS was seven points (range: 2-10 points). In two of our first patients we observed a transient femoral nerve palsy (completely resolved at follow-up) and 15 patients reported numbness in the area of the lateral cutaneous femoral nerve.

CONCLUSIONS

Treatment of anterior femoroacetabular impingement through an arthroscopically assisted mini-open anterior approach can reduce pain and improve function in a short-term observation period. Femoral osteochondroplasty as well as surgical treatment of acetabular cartilage and labrum lesions are possible, but the access is limited to the anterior and anterolateral part of the hip joint.

Evaluation of a computed tomography-based navigation system prototype for hip arthroscopy in the treatment of femoroacetabular cam impingement

PURPOSE

The purpose of this study was to investigate the impact of a new computed tomography-based computer navigation system on the accuracy of arthroscopic offset correction in patients with cam type femoroacetabular impingement (FAI), and to evaluate if the accuracy of offset restoration compromises the early clinical outcome.

METHODS

We prospectively treated 50 patients (25 navigated and 25 non-navigated) by hip arthroscopy and arthroscopic offset restoration for cam FAI. The patients were a mean age 42.9 years, and the average follow-up was 26.7 months, with no patients lost to follow-up. Magnetic resonance imaging scans were performed preoperatively and 6 weeks postoperatively. A postoperative alpha angle of less than 50 degrees or a reduction of the alpha angle of more than 20 degrees was considered to be successful offset restoration. Outcomes were measured with a visual analogue scale for pain, range of motion, and the nonarthritic hip score.

RESULTS

The mean alpha angle improved from 76.5 degrees (range, 57 degrees to 110 degrees) to 54.2 degrees (range, 40 degrees to 84 degrees). In both the navigated and the non-navigated groups, 6 patients (24%) showed insufficient offset correction. Range of motion, visual analogue scale for pain scores, and nonarthritic hip scores significantly improved in all subgroups. Statistical analysis showed no significant difference regarding the clinical outcome between patients with sufficient and insufficient correction of the alpha angle.

CONCLUSIONS

In this series, a significant percentage of patients (24%) showed an insufficient correction of the alpha angle after hip arthroscopy for cam FAI. This study shows that the presented navigation system could not improve this rate and that the insufficient accuracy of reduction of the alpha angle does not appear to compromise the early clinical outcome.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

[Femoroacetabular impingement: radiographic diagnosis--what the radiologist should know]

OBJECTIVE

The purpose of this article is to show the important radiographic criteria that indicate the two types of femoroacetabular impingement: pincer and cam impingement. In addition, potential pitfalls in pelvic imaging concerning femoroacetabular impingement are shown.

CONCLUSION

Femoroacetabular impingement is a major cause for early "primary" osteoarthritis of the hip. It can easily be recognized on conventional radiographs of the pelvis and the proximal femur.

Groin pain after open FAI surgery: the role of intraarticular adhesions

Femoroacetabular impingement (FAI) is an established cause of osteoarthrosis of the hip. Surgery is intended to remove the cause of impingement with hip dislocation and resection of osseous prominences of the acetabular rim and of the femoral head-neck junction. Using the Merle d'Aubigné score and qualitative categories, recent studies suggest good to excellent outcomes in 75% to 80% of patients after open surgery with dislocation of the femoral head. Unsatisfactory outcome is mainly related to pain, located either in the area of the greater trochanter or in the groin. There are several reasons for persisting groin pain. Joint degeneration with joint space narrowing and/or osteophyte formation, insufficient correction of the acetabula, and femoral pathology are known factors for unsatisfactory outcome. Recently, intraarticular adhesions between the femoral neck and joint capsule have been identified as an additional cause of postoperative groin pain. The adhesions form between the joint capsule and the resected area on the femoral neck and may lead to soft tissue impingement. MR-arthrography is used for diagnosis and the adhesions can be treated successfully by arthroscopy. While arthroscopic resection improves outcome it is technically demanding. Avoiding the formation of adhesions is important and is perhaps best accomplished by passive motion exercises after the initial surgery.

ARTHROSCOPIC TREATMENT OF FEMOROACETABULAR IMPINGEMENT

OBJECTIVE

The purpose of this study is to evaluate the short-term follow-up results of arthroscopic treatment of femoroacetabular impingement. Our hypothesis is that arthroscopic treatment results are favorable.

METHODS

Between August 2003 and August 2007, 28 hips had femoroacetabular impingement treated by hip arthroscopy. The mean age was 34 years, with mean follow-up period of 27 months. Clinical results were graded with the modified Harris hip score, which was measured pre- and postoperatively. Patients had also their internal rotation analyzed. These parameters were calculated by using Wilcoxon's t test for analysis of nonparametric paired samples performed.

RESULTS

The mean preoperative Harris Hip Score was 54.2, improving to 94.8 postoperatively (p<0,001). The mean increase was 37.5 points. We had 4 good results (15%) and 24 excellent results (85%). Preoperatively, the patients had a mean internal rotation of 17°, and, postoperatively, 36°. The average internal rotation increase was 19° (p<0,001).

CONCLUSIONS

The arthroscopic treatment of femoroacetabular impingement presents satisfactory results.

Hip disease in the young, active patient: evaluation and nonarthroplasty surgical options

As a distinct entity, femoroacetabular impingement has been suggested to be a preosteoarthritic mechanism. The condition occurs when the proximal femur repeatedly comes into contact with the native acetabular rim during normal hip range of motion. Early diagnosis and surgical management are imperative to delay degenerative changes associated with these conditions. Femoroacetabular impingement is most prevalent in young, active patients. Physical examination should include evaluation of gait and foot progression angle, as well as leg length measurement, hip range of motion, and abductor strength. Imaging studies, including plain radiographs and magnetic resonance arthrography, aid in accurate diagnosis. Surgical treatment options include surgical hip dislocation, periacetabular osteotomy, and hip arthroscopy.

Arthroscopy of the hip joint: indication, technique, results

INTRODUCTION

It is the aim of this study to demonstrate which disorders of the hip joint can and should be treated by hip arthroscopy.

METHOD

The technique and results of hip arthroscopy in different indications are evaluated and presented by means of a selective analysis of the literature, together with the author's own experience.

RESULTS

Arthroscopy of the hip is a successful procedure for the treatment of loose bodies, traumatic and degenerative lesions of the acetabular labrum, ligamentum capitis femoris, and cartilage, femoroacetabular impingement, synovial disorders, and septic arthritis.

DISCUSSION

The published studies attain a level of evidence IV. Although no data on the long-term outcome are available, it can be concluded that hip arthroscopy has become an important option for treatment of disorders of the hip. As an established component of the treatment algorithm, hip arthroscopy closes the gap between conservative and invasive procedures.

Arthroscopic management of femoroacetabular impingement: early outcomes measures

PURPOSE

The purpose of this study was to evaluate the early outcomes of arthroscopic management of femoroacetabular impingement (FAI).

METHODS

Ninety-six consecutive patients (100 hips) with radiographically documented FAI were treated with hip arthroscopy, labral debridement or repair/refixation, proximal femoral osteoplasty, or acetabular rim trimming (or some combination thereof). Outcomes were measured with the impingement test, modified Harris Hip Score, Short Form 12, and pain score on a visual analog scale preoperatively and postoperatively at 6 weeks, 3 months, and 6 months, as well as yearly thereafter. Preoperative and postoperative radiographic alpha angles were measured to evaluate the adequacy of proximal femoral osteoplasty.

RESULTS

There were 54 male and 42 female patients with up to 3 years' follow-up (mean, 9.9 months). The mean age was 34.7 years. Isolated cam impingement was identified in 17 hips, pincer impingement was found in 28, and both types were noted in 55. Thirty hips underwent labral repair/refixation. A comparison of preoperative scores with those obtained at most recent follow-up revealed a significant improvement (P < .001) for all outcomes measured: Harris Hip Score (60.8 v 82.7), Short Form 12 (60.2 v 77.7), visual analog score for pain (6.74 v 1.88 cm), and positive impingement test (100% v 14%). The alpha angle was also significantly improved after resection osteoplasty. Complications included heterotopic bone formation (6 hips) and a 24-hour partial sciatic nerve neurapraxia (1 hip). No hip went on to undergo repeat arthroscopy, and three hips have subsequently undergone total hip arthroplasty.

CONCLUSIONS

Arthroscopic management of patients with FAI results in significant improvement in outcomes measures, with good to excellent results being observed in 75% of hips at a minimum 1-year follow-up. Alteration in the natural progression to osteoarthritis and sustained pain relief as a result of arthroscopic management of FAI remain to be seen.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Radiological evidence of femoroacetabular impingement in mild slipped capital femoral epiphysis: a mean follow-up of 14.4 years after pinning in situ

Conventional treatment of mild slipped capital femoral epiphysis consists of fixation in situ with wires or screws. Recent contributions to the literature suggest that even a mild slip may lead to early damage of the acetabular labrum and adjacent cartilage by abutment of a prominent femoral metaphysis. It has been suggested that the appropriate treatment in mild slipped capital femoral epiphysis should not only prevent further slipping of the epiphysis, but also address potential femoroacetabular impingement by restoring the anatomy of the proximal femur. Between October 1984 and December 1995 we treated 16 patients for unilateral mild slipped capital femoral epiphysis by fixation in situ with Kirschner wires. In this study we have reviewed these patients for clinical and radiological evidence of femoroacetabular impingement. There was little clinical indication of impingement but radiological evaluation assessing the femoral head-neck ratio and measuring the Nötzli alpha angle on the anteroposterior and cross-table radiographs showed significant alterations in the proximal femur. None of the affected hips had a normal head-neck ratio and the mean alpha angle was 86 degrees (55 degrees to 99 degrees ) and 55 degrees (40 degrees to 94 degrees ) on the anteroposterior and lateral cross-table radiographs, respectively. While our clinical data favours conventional treatment, our radiological findings are in support of restoring the anatomy of the proximal femur to avoid or delay the development of femoroacetabular impingement following mild slipped capital femoral epiphysis.

The etiology of osteoarthritis of the hip: an integrated mechanical concept

The etiology of osteoarthritis of the hip has long been considered secondary (eg, to congenital or developmental deformities) or primary (presuming some underlying abnormality of articular cartilage). Recent information supports a hypothesis that so-called primary osteoarthritis is also secondary to subtle developmental abnormalities and the mechanism in these cases is femoroacetabular impingement rather than excessive contact stress. The most frequent location for femoroacetabular impingement is the anterosuperior rim area and the most critical motion is internal rotation of the hip in 90 degrees flexion. Two types of femoroacetabular impingement have been identified. Cam-type femoroacetabular impingement, more prevalent in young male patients, is caused by an offset pathomorphology between head and neck and produces an outside-in delamination of the acetabulum. Pincer-type femoroacetabular impingement, more prevalent in middle-aged women, is produced by a more linear impact between a local (retroversion of the acetabulum) or general overcoverage (coxa profunda/protrusio) of the acetabulum. The damage pattern is more restricted to the rim and the process of joint degeneration is slower. Most hips, however, show a mixed femoroacetabular impingement pattern with cam predominance. Surgical attempts to restore normal anatomy to avoid femoroacetabular impingement should be performed in the early stage before major cartilage damage is present.

LEVEL OF EVIDENCE

Level V, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Arthroscopic offset restoration in femoroacetabular cam impingement: accuracy and early clinical outcome

PURPOSE

The purpose of this study was to determine the accuracy of arthroscopic restoration of femoral offset as well as the early clinical outcome of arthroscopic debridement and femoral offset restoration and whether there is a correlation between accuracy and outcome.

METHODS

Twenty-two patients with symptomatic femoroacetabular cam impingement underwent arthroscopic correction of the femoral offset and debridement. The alpha angle was measured with magnetic resonance imaging preoperatively and postoperatively for quantification of the offset, and the clinical status was determined by documenting the impingement sign, range of motion, intensity of pain on a visual analog scale, Nonarthritic Hip Score, and complications preoperatively and 6 months postoperatively.

RESULTS

The alpha angle improved from a mean of 75 degrees to 54 degrees. Internal rotation increased from a mean of 5 degrees to 22 degrees, flexion increased from a mean of 107 degrees to 124 degrees, and the pain score decreased from a mean of 5.8 to 1.4. The Nonarthritic Hip Score increased from a mean of 49 to 74 points. No major complications were encountered. Patients with early osteoarthritis did substantially worse than those without it. The alpha angle did not correlate with any clinical outcome measure.

CONCLUSIONS

The femoral offset can be precisely restored via an arthroscopic technique in the treatment of femoroacetabular cam impingement. The early clinical outcome of arthroscopic offset restoration and debridement is good in patients with no or only mild osteoarthritis. The accuracy of correction is not correlated with the early clinical outcome.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Hip arthroscopy after previous surgical hip dislocation for femoroacetabular impingement

PURPOSE

The purpose of this study was to examine whether arthroscopic adhesiolysis can relieve symptoms of patients with persistent pain after open surgical hip dislocation for femoroacetabular impingement syndrome without osseous or cartilaginous alterations.

METHODS

This study comprised 16 consecutive patients (6 men and 10 women; mean age, 33.5 years [range, 19 to 60 years]) with persistent pain without osseous or cartilaginous alterations after surgical hip dislocation for the treatment of femoroacetabular impingement. At index surgery, all patients had osteochondroplasty of the head-neck junction and resection of the acetabular rim with reattachment of the labrum in 9 cases. All patients had preoperative magnetic resonance imaging-arthrogram and were treated with arthroscopy of the hip.

RESULTS

At arthroscopy, all reattached labra were stable. In the cases without preservation of the labrum at the index operation, the joint capsule was attached at the level of the acetabular rim and synovitis was noticed. All patients had adhesions between the neck of the femur and joint capsule or between the labrum and capsule. In 3 patients the arthroscopic procedure was technically limited by massive thickening of the capsule. Overall, 81% of patients (13/16) showed less pain or were pain-free. The Merle d'Aubigné score improved from 13 points preoperatively to 16 points at the last follow-up.

CONCLUSIONS

Persistent pain after surgical dislocation of the hip without evidence of cartilaginous and osseous alterations could result from intra-articular adhesions. Hip arthroscopy after previous surgery can be demanding because of scarring. If the adhesions can be released, good results can be achieved.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Femoroacetabular impingement: radiographic diagnosis--what the radiologist should know

OBJECTIVE

The purpose of this article is to show the important radiographic criteria that indicate the two types of femoroacetabular impingement: pincer and cam impingement. In addition, potential pitfalls in pelvic imaging concerning femoroacetabular impingement are shown.

CONCLUSION

Femoroacetabular impingement is a major cause for early "primary" osteoarthritis of the hip. It can easily be recognized on conventional radiographs of the pelvis and the proximal femur.

Range of motion in anterior femoroacetabular impingement

The range of motion of normal hips and hips with femoroacetabular impingement relative to some specific anatomic reference landmarks is unknown. We therefore described: (1) the range of motion pattern relative to landmarks; (2) the location of the impingement zones in normal and impinging hips; and (3) the influence of surgical débridement on the range of motion. We used a previously developed and validated noninvasive 3-D CT-based method for kinematic hip analysis to compare the range of motion pattern, the location of impingement, and the effect of virtual surgical reconstruction in 28 hips with anterior femoroacetabular impingement and a control group of 33 normal hips. Hips with femoroacetabular impingement had decreased flexion, internal rotation, and abduction. Internal rotation decreased with increasing flexion and adduction. The calculated impingement zones were localized in the anterosuperior quadrant of the acetabulum and were similar in the two groups and in impingement subgroups. The average improvement of internal rotation was 5.4 degrees for pincer hips, 8.5 degrees for cam hips, and 15.7 degrees for mixed impingement. This method helps the surgeon quantify the severity of impingement and choose the appropriate treatment option; it provides a basis for future image-guided surgical reconstruction in femoroacetabular impingement with less invasive techniques.