Age-Associated Changes in Proximal Femur Morphology Affect Femoral Component Sizing in Cementless Hip Arthroplasty.

Background: In cementless hip arthroplasty, the femoral component should obtain firm fixation within the endosteal bone and achieve adequate reconstruction of hip joint biomechanics simultaneously. Previous anatomical studies described age-related changes of the proximal femoral canal, such as canal widening, which theoretically necessitates the use of larger stem sizes in elderly patients. This study examines a potential association between patients' age at surgery and the implant size of a cementless femoral component. Material and methods: A total of 13,423 primary hip arthroplasties with a single cementless stem registered in the Dutch Arthroplasty Register (LROI) were included. Patient characteristics (ie patients' age, sex, height and weight at time of surgery) and femoral component size were derived. A one-way ANCOVA was used to compare the mean stem size between age groups, and multivariable linear regression analysis was used in order to investigate to which extent ageing impacted stem size. Results: Each subsequent age- group (ten-year intervals) had a significantly larger mean stem size than the prior age- group. Multivariable linear regression analysis revealed that age is positively correlated with stem size and that this correlation is more prominent in females than in males (beta = .046, P < .001 and beta = .028, P < .001 respectively). Interpretation: Implant size is positively correlated with age, in particular in females and independently from investigated anthropometric characteristics. The present study endorses that the femoral canal morphology is related to patients' characteristics such as age and sex. The morphology will subsequently influence implant sizing and therefore may have biomechanical and clinical implications.

Metallic hemiarthroplasty or arthrodesis of the first metatarsophalangeal joint as treatment for hallux rigidus: A systematic review and meta-analysis.

BACKGROUND: Arthrodesis and metallic hemiarthroplasty are two surgical interventions for the treatment of end-stage osteoarthritis of the first metatarsophalangeal (MTP1) joint. This systematic review and meta-analysis aims to compare the two operations with regards to patient-reported outcomes, pain reduction, complications and revision rates. METHODS: A systematic literature search identified all relevant studies. The methodological quality was assessed using two validated tools. Data of interest were derived and presented. For non-comparative studies, data was assessed for trends, while for comparative studies pooling statistics were performed. RESULTS: A total of 33 studies were included for analysis. The majority of studies (>75%) reported an AOFAS-HMI score greater than 80 points after both metallic hemiarthroplasty and arthrodesis. The lowest VAS pain score was observed after arthrodesis (weighted mean difference -1.58, 95% confidence interval (CI) -2.16 to -1.00 P< 0.00001). Comparable numbers of complications (odds radio 1.48, 95% CI 0.81 to 2.73, P = 0.21, favoring: hemiarthroplasty) and revisions (odds ratio 1.16, 95% CI 0.62 to 2.15 P = 0.64, favoring: hemiarthroplasty) were observed after both interventions. The included non-comparative studies seem to confirm these findings of the comparative studies. CONCLUSION: Metallic hemiarthroplasty and arthrodesis have excellent clinical outcomes and acceptable complication- and revision rates. Arthrodesis seems to be superior in pain reduction, while metallic hemiarthroplasty is a suitable alternative for patients performing activities that requires motion in the first metatarsophalangeal joint.

Femoral Head Size is Correlated With Head Position in Very Elderly Patients.

BACKGROUND: In cases of femoral neck fracture, it is often not possible to accurately determine the original position of the head center to assess appropriate restoration of leg length. The aim of this study was to determine the accuracy of predicting the position of the femoral head center based on new and established correlations between the femoral head diameter (FHD) and the distance between the lesser trochanter and the femoral head center (LT-FHC) in the very elderly (aged ≥80 years) as the mainly affected but yet underinvestigated group. METHODS: The FHD and the LT-FHC distance were determined in 148 subjects (104 males, 44 females); 90 aged ≥80 years and 58 aged <80 years. For each age and gender subgroup one specific (LT-FHC)/FHD ratio was determined. The accuracy of the new determined ratios and the established ratios by others were compared by recalculating the LT-FHC distance of each individual subject. RESULTS: The FHD and the LT-FHC were significantly correlated, most strongly in elderly females (R = 0.554, P < .001). Using the new age- and gender-specific ratios, the LT-FHC distance could be predicted within 10 mm of the true value in 95% of the cases and in only 77% using previously reported formulas. CONCLUSION: Age- and gender-specific formulas yield higher accuracy than generic formulas. The formulas presented in this study can offer a practical, easy to use instrument for orthopedic surgeons performing hip arthroplasty in very elderly patients in addition to classic techniques to prevent significant leg-length discrepancy.

The Femoral Head Center Shifts in a Mediocaudal Direction During Aging.

BACKGROUND: Accurate reconstruction of hip joint biomechanics is the key stone in total hip arthroplasty. Although proximal femur morphology is known to vary with both age and gender, few studies investigated this in the very elderly (ie, ≥80 years). The purpose of this study was to compare basic morphological parameters describing the position of the femoral head between very elderly and middle-aged subjects. METHODS: Computed tomographic scans of the femur of 90 very elderly (mean 84 years, range 80-105 years) and 58 middle-aged subjects (mean 52 years, range 20-79 years) were made. After 3-dimensional reconstruction, the neck-shaft angle, femoral neck anteversion angle, femoral head height, femoral neck length, and mediolateral offset (ML-offset) were determined. RESULTS: The neck-shaft angle was on average 3.6° less in elderly males (125.9° ± 5.0°) than in middle-aged males (129.5° ± 5.1°) (P < .001). The femoral neck anteversion angle was not significantly different between both age and gender groups. The femoral head height was -12.3 mm in elderly females compared to -10.5 mm (Δ 17%) in elderly males (P = .284) and even -8.0 mm (Δ 54%) in middle-aged males. The ML-offset was 10% (4.1 mm) larger in elderly compared to middle-aged males (P < .001). CONCLUSION: These findings suggest that the femoral neck and head shift in a relative varus position during aging. Femoral prostheses with increased ML-offset and a lower caput-collum-diaphyseal angle are needed to accommodate the morphology of the femur in the very elderly. Care must be taken not to lengthen the operated leg, particularly in very elderly females.