The association between femoral neck shaft angle and degenerative disease of the hip in a cadaveric model

BACKGROUND

While the influences of acetabular dysplasia and overcoverage on hip arthritis have been studied, the impact of femoral neck-shaft angle on hip arthritis is much more poorly understood. The purpose of this study is to determine if a relationship exists between neck shaft angle and the development of osteoarthritis, a better understanding of which would be useful to surgeons planning osteotomies about the hip.

METHODS

533 cadaveric femora and acetabulae (1066 total) from the Hamann-Todd Osteological Collection (Cleveland, OH) were acquired. We measured true neck shaft angle using an AP photograph with the femoral neck parallel to the table. Femoral head volume to acetabular volume ratio, representing femoral head coverage, as well as femoral version were utilised. Correlation between neck shaft angle, femoral version, femoral head coverage and osteoarthritis were evaluated with multiple regression analysis.

RESULTS

The mean age and standard deviation was 56 ± 10 years. There were 64 females (12%) and 469 males. There were 380 Caucasians (71%) and 153 African-Americans. Mean femoral version was 11° ± 12° and mean true neck shaft angle was 127.7° ± 5.9° There was a strong correlation between age and arthritis (standardised beta 0.488, p < 0.001). There was a significant correlation between increasing true neck shaft angle and decreasing hip arthritis (standardised beta -0.024, p = 0.038). In the femoral head overcoverage subset, increasing true neck shaft angle was still significantly associated with decreasing hip arthritis (standardised beta -0.088, p = 0.018), although this relationship was not significant with femoral head undercoverage subset.

CONCLUSIONS

With sufficient acetabular coverage, a relative increase in femoral neck shaft angle within the physiologic range is associated with decreased hip osteoarthritis.

CLINICAL RELEVANCE

An understanding of the relationship between femoral neck shaft angle and hip osteoarthritis could be useful for surgeons planning pelvic or proximal femur osteotomies in children.

Multivariate analysis of the relationship between gluteal muscle contracture and coxa valga

Background

Gluteal muscle contracture (GMC) is a disease characterized by the limited function of the hip joint, knee pain, and abnormal gait. There is a lack of research on the effect of GMC on the hip joint structure to date. This study aims to analyze the association between GMC and the deformity of the hip and pelvis.

Methods

Standing anteroposterior pelvic radiographs of 214 patients (152 with gluteal muscle contracture and 62 without gluteal muscle contracture) were retrospectively collected. Neck–shaft angle, lateral center edge angle, Tönnis angle, femoral head coverage index, acetabular depth, Sacro-femoral-pubic angle, and obturator foramen ratio were respectively measured and included in the following statistical analysis. The collected data were analyzed using logistical regression and multiple linear regression to explore the factors influencing coxa valga and SFP angle.

Results

GMC was identified as a common factor significantly associated with coxa valga and increased SFP angle. There is a difference of risk factors in logistic regression for coxa valga between the left and right sides.

Conclusion

GMC is a significant risk factor for coxa valga and increased SFP angle. Given that GMC can cause coxa valga and likely alter the pelvis’s position, GMC should be paid attention to and treated early.

Statistical shape modeling of the hip and the association with hip osteoarthritis: a systematic review

OBJECTIVE

To summarize available evidence on the association between hip shape as quantified by statistical shape modeling (SSM) and the incidence or progression of hip osteoarthritis.

DESIGN

We conducted a systematic search of five electronic databases, based on a registered protocol (available: PROSPERO CRD42020145411). Articles presenting original data on the longitudinal relationship between radiographic hip shape (quantified by SSM) and hip OA were eligible. Quantitative meta-analysis was precluded because of the use of different SSM models across studies. We used the Newcastle-Ottawa Scale (NOS) for risk of bias assessment.

RESULTS

Nine studies (6,483 hips analyzed with SSM) were included in this review. The SSM models used to describe hip shape ranged from 16 points on the femoral head to 85 points on the proximal femur and hemipelvis. Multiple hip shape features and combinations thereof were associated with incident or progressive hip OA. Shape variants that seemed to be consistently associated with hip OA across studies were acetabular dysplasia, cam morphology, and deviations in acetabular version (either excessive anteversion or retroversion).

CONCLUSIONS

Various radiographic, SSM-defined hip shape features are associated with hip OA. Some hip shape features only seem to increase the risk for hip OA when combined together. The heterogeneity of the used SSM models across studies precludes the estimation of pooled effect sizes. Further studies using the same SSM model and definition of hip OA are needed to allow for the comparison of outcomes across studies, and to validate the found associations.

Radiographic characteristics of the hip joint in skeletally mature patients with multiple hereditary exostoses

OBJECTIVE

To elucidate the radiological characteristics of the hips, especially in proximal femur, of skeletally mature patients with multiple hereditary exostoses (MHE).

MATERIALS AND METHODS

Fifty eligible patients (100 hips) were included in the study and assigned to the MHE group. The control group included age- and sex-matched individuals, and the radiographs of 100 hips were used as controls. We examined the anatomical characteristics of the acetabulum and the proximal femur, including the acetabular depth-width ratio (ADR), Sharp's angle, femoral neck-shaft angle (NSA), Wiberg's centre-edge angle (CEA), femoral neck axis length (FNAL), femoral head diameter, (FHD), femoral neck width (FNW), femoral shaft width (FSW), femoral neck-shaft angle (NSA), and femoral head-neck ratio (FHNR = FHD/FNW). p value < 0.05 was considered significant.

RESULTS

Osteochondroma was frequently observed in the medial femoral neck (79%), but it was rarely found in the femoral head (1%). ADR and Sharp's angle were not significantly different between the MHE and control groups (p = 0.2056, p = 0.5025). CEA was significantly different between the two groups (p < 0.0001). FNW was significantly larger in the MHE group than in the control group (p < 0.0001). FHNR was significantly different between the two groups (p < 0.0001). NSA was significantly larger than the MHE group (141.8° ± 9.7° vs 129.5° ± 5.6°, p < 0.0001).

CONCLUSIONS

Hip dysplasia in the pelvic side was not commonly observed in skeletally mature MHE patients. However, they showed femoral neck widening and coxa valga. The occurrence of osteochondroma around the femoral neck affects the degree of valgus deformity. These facts could be useful for orthopaedic surgeons treating MHE patients.

Femoral neck osteotomy in skeletally mature patients: surgical technique and midterm results

PURPOSE

Using an extended retinacular flap containing the blood supply for the femoral head, proximal femur osteotomies can be performed at the neck level increasing the potential of correction of complex morphologies. The aim of this study was to analyze the safety, clinical, and radiographic results of this intra-articular surgical technique performed in skeletally mature patients with a minimum follow-up of three years.

METHODS

Fourteen symptomatic adult patients (16 hips) with a mean age of 26 years underwent FNO using surgical hip dislocation and an extended soft tissue flap. Radiographs and radial magnetic resonance imaging (MRI) were obtained before and after surgery to evaluate articular congruency, cartilage damage, and morphologic parameters. Clinical functional evaluation was done using the Nonarthritic Hip Score (NAHS), the Hip Outcome Score (HOS), and the modified Harris Hip Score (mHHS).

RESULTS

After surgery, no avascular necrosis was observed, and all the osteotomies healed without complication. The initial neck/shaft angle (range 120 to 150°) improved in all cases to a mean value of 130° ± 4.6 (p < 0.001). In eight of nine valgus hips, the high-positioned fovea capitis changed to a normal position after surgery. The NAHS score improved from a mean of 36.5 ± 14.9 to 82.9 ± 13.9 points after surgery (p < 0.001). After surgery, the mean HOS was 87.1 ± 17.6 points, and the mean mHHS was 78.6 ± 17 points.

CONCLUSIONS

In this series, femoral neck osteotomy in the adult, although technically more demanding compared with other classic osteotomies, can be considered a safe procedure with considerable potential to correct hip deformities.

Femoral neck shortening after internal fixation of Garden I fractures increases the risk of femoral head collapse

BACKGROUND

Arthroplasty has not been proven superior over internal fixation for the treatment of non-displaced femoral neck fractures. However, internal fixation has been followed by high rates of revision for mechanical complications and of femoral neck impaction within the first postoperative year. The objective of this study was to determine whether femoral neck impaction was associated with avascular necrosis (AVN).

HYPOTHESIS

Fracture healing with femoral neck shortening by impaction after internal fixation of a femoral neck fracture is associated with AVN.

MATERIAL AND METHODS

A single-centre retrospective study in patients with Garden I fractures managed by screw fixation was performed to compare outcomes in the groups with and without femoral neck impaction. Follow-up radiographs were assessed for evidence of the femoral neck impaction during fracture healing. The occurrence of AVN was the primary evaluation criterion. The secondary evaluation criteria were risk factors for impaction and complications.

RESULTS

Of the 75 included patients, 9 (12%) experienced AVN. Impaction was significantly associated with AVN (p=0.02; relative risk, 4.38). Significant risk factors for impaction were a higher body mass index (p=0.0003) and valgus-impacted fracture reduction between the radiographs at baseline and immediately after surgery (p=0.0001).

DISCUSSION

Femoral neck impaction was a significant risk factor for AVN after screw fixation of Garden I fractures. Valgus-impacted fracture reduction must receive careful attention during fixation. We suggest static internal fixation if the impaction is reduced on a traction table and advise caution when using parallel screws. The diagnostic and therapeutic strategy proposed here deserves to be evaluated in a prospective study.

LEVEL OF EVIDENCE

III, retrospective comparative study.

Determinants of Hip and Femoral Deformities in Children With Spastic Cerebral Palsy

Objective

To find factors affecting hip and femoral deformities in children with spastic cerebral palsy (CP) by comparing various clinical findings with imaging studies including plain radiography and computed tomography (CT) imaging.

Methods

Medical records of 709 children with spastic CP who underwent thorough baseline physical examination and functional assessment between 2 to 6 years old were retrospectively reviewed. Fifty-seven children (31 boys and 26 girls) who had both plain radiography of the hip and three-dimensional CT of the lower extremities at least 5 years after baseline examination were included in this study.

Results

The mean age at physical examination was 3.6 years (SD=1.6; range, 2–5.2 years) and the duration of follow-up imaging after baseline examination was 68.4 months (SD=22.0; range, 60–124 months). The migration percentage correlated with motor impairment and the severity of hip adductor spasticity (R1 angle of hip abduction with knee flexion). The femoral neck and shaft angle correlated with the ambulation ability and severity of hip adductor spasticity (R1 and R2 angles of hip abduction with both knee flexion and extension).

Conclusion

Hip subluxation and coxa valga deformity correlated with both dynamic spasticity and shortening of hip adductor muscles. However, we found no correlation between femoral deformities such as femoral anteversion, coxa valga, and hip subluxation.

[Surgical therapy of ischiofemoral impingement by lateralizing intertrochanteric osteotomy]

OBJECTIVE

Lateralizing, derotating intertrochanteric varus osteotomy to increase the ischiofemoral space to counter painful impingement of the lesser trochanter and the os ischium with resulting entrapment of quadratus femoris muscle.

INDICATIONS

Symptomatic ischiofemoral impingement (IFI) caused by Coxa valga et antetorta, Coxa valga or Coxa antetorta, or a short femoral neck.

CONTRAINDICATIONS

Anatomic configuration suggestive of IFI in asymptomatic patients. Symptomatic IFI caused by another underlying pathology. Valgus deformity of the knee.

SURGICAL TECHNIQUE

Measurement of femoral antetorsion. Planning of the osteotomy, lateralization, varus angle for correction, rotation and offset correction, leg length change, and osteosynthesis plate. General or spinal anesthesia in supine or lateral position. Skin incision (15 cm) beginning lateral of the greater trochanter tip, distally along the axis of the femur. Preparation onto the femur by L‑shaped dissection of the vastus lateralis from the bone. A Kirschner(K-)wire is then positioned along the anterior femoral neck to designate the femoral neck antetorsion. A triangle set on the lateral femoral cortexis is used to determine the osteotomy angle. In the thus determined angle, a second K‑wire is shot centrally along the femoral neck axis just inferior to its cranial cortex. About 5 mm distal to the second wire, the entry for the blade is prepared using a drill. Using the blade setting instrument, the blade is introduced into the femoral neck, then slightly pulled back. The rotation is then marked on the anterior femoral cortex proximal and distal to the planned osteotomy and the osteotomy is performed. A blade plate without displacement is impacted. The osteotomy is then reduced, the distal fragment pulled laterally onto the plate, and the screws inserted after compression of the osteotomy with a tension device.

POSTOPERATIVE MANAGEMENT

Touch-toe bearing for 6 weeks, then radiological assessment of osteotomy healing before an increase in weight bearing (15 kg/week). Hip flexion limited to 90° for 6 weeks. Elective implant removal after 12-18 months.

RESULTS

Studies of this lateralizing varus osteotomy have not been published. The 25-year results of the conventional derotating intertrochanteric varus osteotomy technique show good functional results and low complication rates, with non-union being the most common. Arthroscopic resection of the lesser trochanter has been reported as a surgical alternative in the treatment of IFI in case reports and small series. Advantages of the osteotomy are the restoration of biomechanics and preservation of iliopsoas tendon insertion.