Hip morphology and its relationship to pathology: Dyplasia to impingement

Subchondral bone deterioration in femoral heads in patients with osteoarthritis secondary to hip dysplasia: A case-control study

Objectives

Residual hip dysplasia is the most common underlying condition leading to secondary osteoarthritis (OA) of the hip. Subchondral bone alterations in OA secondary to hip dysplasia (HD-OA) are poorly investigated. The aim of the present study was to analyse the microarchitecture, bone remodelling and pathological alterations of subchondral bone in femoral heads from patients with HD-OA.

Methods

Subchondral bone specimens were extracted from both weight-bearing and non–weight-bearing regions of femoral heads from 20 patients with HD-OA and 20 patients with osteoporotic femoral neck fracture, during hip replacement surgery. Micro-CT and histological examination were performed to assess the microarchitecture and histopathological changes.

Results

The weight-bearing subchondral bone showed significantly more sclerotic microarchitecture and higher bone remodelling level in HD-OA as compared with osteoporosis. In the non–weight-bearing region, the two diseases shared similar microarchitectural characteristics, but higher bone remodelling level was detected in HD-OA. Distinct regional differences were observed in HD-OA, whereas the two regions exhibited similar characteristics in osteoporosis. In addition, HD-OA displayed more serious pathological alterations, including subchondral bone cyst, metaplastic cartilaginous tissue, bone marrow oedema and fibrous tissue, especially in the weight-bearing region.

Conclusions

Osteoarthritic deteriorations of subchondral bone induced by hip dysplasia spread throughout the whole joint, but exhibit region-dependent variations, with the weight-bearing region more seriously affected. Biomechanical stress might exert a pivotal impact on subchondral bone homeostasis in hip dysplasia.

The translational potential of this article

The histomorphometric findings in the project indicate an early intervention for the development of hip dysplasia in clinic.

M-Mode Ultrasound Reveals Earlier Gluteus Minimus Activity in Individuals With Chronic Hip Pain During a Step-down Task

STUDY DESIGN

Controlled laboratory study.

BACKGROUND

The hip abductor muscles are important hip joint stabilizers. Hip joint pain may alter muscle recruitment. Motion-mode (M-mode) ultrasound enables noninvasive measurements of the onset of deep and superficial muscle motion, which is associated with activation onset.

OBJECTIVES

To compare (1) the onset of superficial and deep gluteus medius and gluteus minimus muscle motion relative to the instant of peak ground reaction force and (2) the level of swing-phase muscle motion during step-down between subjects with chronic hip pain and controls using M-mode ultrasound.

METHODS

Thirty-five subjects with anterior, nontraumatic hip pain for more than 6 months (mean ± SD age, 54 ± 9 years) and 35 controls (age, 57 ± 7 years) were scanned on the lateral hip of the leading leg during frontal step-down onto a force platform using M-mode ultrasound. Computerized motion detection with the Teager-Kaiser energy operator was applied on the gluteus minimus and the deep and superficial gluteus medius to determine the time lag between muscle motion onset and instant of peak ground reaction force and the level of gluteus minimus motion during the swing phase. Time lags and motion levels were averaged per subject, and t tests were used to determine between-group differences.

RESULTS

In participants with hip pain, gluteus minimus motion onset was 103 milliseconds earlier (P = .002) and superficial gluteus medius motion was 70 milliseconds earlier (P = .047) than those in healthy control participants. The level of gluteus minimus swing-phase motion was higher with pain (P = .006).

CONCLUSION

Increased gluteus minimus motion during the swing phase and earlier gluteus minimus and superficial gluteus medius motion in individuals with hip pain suggest an overall increase of muscle activity, possibly a protective behavior.

Arthroscopic treatment for chondral lesions of the hip

Arthroscopic treatment of chondral lesions of the hip is challenging. Understanding the etiology is paramount not only in treating hip chondral damage but also in mitigating the cause, using arthroscopic means. This article addresses chondral lesions of the hip caused by either injury or morphologic conflicts such as seen in femoroacetabular impingement. Fractures, aseptic necrosis, and metabolic or immunologic damage are not addressed. Methods using arthroscopic surgery for the treatment of chondral lesions are presented.

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.

Surgical correction of "cam-type" femoroacetabular impingement: a cadaveric comparison of open versus arthroscopic debridement

PURPOSE

The goal of this study was to compare open and arthroscopic surgical techniques for "cam-type" femoroacetabular impingement in terms of feasibility and reliability.

METHODS

We used 5 fresh-frozen cadaver specimens (10 hips). Anteroposterior and cross-table radiographs were taken for each. The head-neck union diameter was measured for each. The amount of bone resection at the anterolateral quadrant of the head-neck union was planned for each, with specific references to width, length, depth, and position. One side was randomly assigned to the open group and the other to the arthroscopic group. Surgical time, position of the osteotomy, and variation of the length, width, and depth of the final osteotomy with respect to the proposed dimensions were compared.

RESULTS

In all specimens partial resection of the anterior-lateral femoral head-neck junction with improvement of the femoral head-neck offset was accomplished. A statistically significant difference (P < .05) was observed for surgical time between the open and arthroscopic groups (shorter in open group).

CONCLUSIONS

When comparing surgical precision, no statistically significant differences were found between the open and arthroscopic procedures in any of the measurements. The depth and width of the osteoplasty were reliably obtained by the arthroscopic technique. However, there was a tendency to underestimate the osteoplasty length with the arthroscopic procedure. Positioning the osteoplasty was also less reliable with the arthroscopic procedure than with the open procedure because of the tendency to place the osteoplasty more posterior and distally than intended.

CLINICAL RELEVANCE

Surgical resection of the femoral neck prominence and/or part of the anterolateral neck has been reported to improve femoral head offset and alleviate impingement. This study attempts to document the accuracy of this resection when done arthroscopically compared with an open procedure.

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.

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.

Descriptive profile of hip rotation range of motion in elite tennis players and professional baseball pitchers

BACKGROUND

Repetitive loading to the hip joint in athletes has been reported as a factor in the development of degenerative joint disease and intra-articular injury. Little information is available on the bilateral symmetry of hip rotational measures in unilaterally dominant upper extremity athletes.

HYPOTHESIS

Side-to-side differences in hip joint range of motion may be present because of asymmetrical loading in the lower extremities of elite tennis players and professional baseball pitchers.

STUDY DESIGN

Cohort (cross-sectional) study (prevalence); Level of evidence, 1.

METHODS

Descriptive measures of hip internal and external rotation active range of motion were taken in the prone position of 64 male and 83 female elite tennis players and 101 male professional baseball pitchers using digital photos and computerized angle calculation software. Bilateral differences in active range of motion between the dominant and nondominant hip were compared using paired t tests and Bonferroni correction for hip internal, external, and total rotation range of motion. A Pearson correlation test was used to test the relationship between years of competition and hip rotation active range of motion.

RESULTS

No significant bilateral difference (P > .005) was measured for mean hip internal or external rotation for the elite tennis players or the professional baseball pitchers. An analysis of the number of subjects in each group with a bilateral difference in hip rotation greater than 10 degrees identified 17% of the professional baseball pitchers with internal rotation differences and 42% with external rotation differences. Differences in the elite male tennis players occurred in only 15% of the players for internal rotation and 9% in external rotation. Female subjects had differences in 8% and 12% of the players for internal and external rotation, respectively. Statistical differences were found between the mean total arc of hip range of internal and external rotation in the elite tennis players with the dominant side being greater by a clinically insignificant mean value of 2.5 degrees. Significantly less (P < .005) dominant hip internal rotation and less dominant and nondominant hip total rotation range of motion were found in the professional baseball pitchers compared with the elite male tennis players.

CONCLUSION

This study established typical range of motion patterns and identified bilaterally symmetric hip active range of motion rotation values in elite tennis players and professional baseball pitchers. Asymmetric hip joint rotational active range of motion encountered during clinical examination and screening may indicate abnormalities and would indicate the application of flexibility training, rehabilitation, and further evaluation.

The Role of Hip Arthroscopy in the Athletic Hip

Hip joint problems in the athlete can be disabling, yet remain elusive to investigation. The arthroscope has proved essential in both the detection and treatment of many of these disorders. Less invasive methods with quicker return to safe competition has been a sine qua non of sports medicine. The incentive to return motivated athletes to a sport has proven fertile ground for advancement of arthroscopic techniques. This has been especially exemplified in the rapidly evolving field of hip arthroscopy, and has allowed these methodologies to find application in the management of patients of all levels of activity. As has been stated, the athletic field of competition represents one of the most fertile clinical laboratories in the world.

Arthroscopic treatment of femoroacetabular impingement

The etiology of degenerative joint disease of the hip remains unsolved. A precursor for some patients, especially younger ones, may be hip impingement. Repetitive microtrauma at maximal flexion can cause chronic pain from the abutment at the femoral head-neck junction caused by an abnormal offset. Chronic impingement from an aspherical head can lead to degenerative labral tears and acetabular chondral degeneration, which may contribute to the degenerative cascade. Arthroscopic treatment of hip impingement caused by an abnormal head-neck offset improves symptoms, restores hip morphology, and ultimately may halt the progression toward degenerative joint disease in certain patients. Early results show that if debridement of the impinging lesion and injured labrum is performed in the setting of normal femoral and acetabular articular surfaces, the results are promising.

Degeneration in dysplastic hips. A computer tomography study

BACKGROUND

Hip dysplasia is considered pre-osteoarthritic, causing degeneration in young individuals.

OBJECTIVE

To determine the pattern of degenerative change in moderate to severely dysplastic hips in young patients.

DESIGN AND PATIENTS

One hundred and ninety-three consecutively-referred younger patients with hip pain believed to be caused by hip dysplasia constituted the study cohort. The average age was 35.5 years (range, 15-61 years). They were examined by close-cut transverse pelvic and knee computed tomography and antero-posterior radiographs (CT). We identified 197 hips with moderate to severe dysplasia, and 78 hips with normal morphology in the study cohort, whilst 111 hip joints were borderline dysplastic according to preset definitions. Comparative analyses of anatomy and distribution of degeneration between dysplastic and normal hips in the study cohort were performed.

RESULTS

In dysplastic hips the anterior acetabular sector angle was significantly and inversely associated to femoral anteversion (p < 0.001). The center-edge (CE) angle, the acetabular angle (AA), and the acetabular depth ratio (ADR) were significantly interrelated (p < 0.001; correlation coefficients ranging from -0.8 to 0.7). Fifty-one hips were subluxated (24R/27L). There were no cases of complete dislocation. The formation of subchondral cysts or osteophytes in dysplastic hips was significantly associated with reduced minimum joint space width (p ranging from 0.005 to 0.02). However, in 67 hips with acetabular cysts, only 6 hips had minimum joint space widths = 2.0 mm (8.9%) in the coronal plane. In 96 cases with acetabular cysts found in the sagittal plane, 43 cases had minimum joint space widths = 2.0 mm (44.7%). Bony rim detachment at the site of labral insertion was recorded in 30 hips. Twenty-three of these were dysplastic (p = 0.01).

CONCLUSIONS

Degeneration was most often found in the anterolateral part of the dysplastic hip joints. Most cysts were located above the transition zone between the bony and the fibrocartilaginous acetabulum, and we found a significantly- increased number of cases with avulsed bony fragments at the antero-lateral labral insertion in dysplastic hips compared to normal hips. It seems likely that the early degenerative process in dysplastic hips originates at the watershed zone between the acetabular labrum and the acetabular cartilage in response to subluxation and femoroacetabular impingement.