Abstract
INTRODUCTION:
Proximally coated femoral stems have been designed to address the shortcomings of fully coated femoral stems including proximal femoral stress shielding. The design improvements leading to more optimized proximal femoral loading condition in the “Neck preserving stems” have increased the popularity of such implants (e.g., Minihip). Neck preserving stems depict better biological outcomes compared to more traditional stems 1 by utilizing more natural mechanical stress/strain distribution over the femur. These stems provide significant reduction in both torsional and bending moments at the stem/bone interface. This reduction may result in decreasing the micromotion and failure of osseointegration 1. Figure 1 demonstrates the differences between the cutting areas of a neck preserving versus traditional stem. The Minihip stem demonstrate a curved structure that is designed to match the shape of the femoral neck. The stability of the implant is achieved in the femoral neck and intertrochanteric area of the proximal femur. Further investigations are needed to establish a solid ground for the outcome of these stem in total hip arthroplasty (THA).
OBJECTIVES:
The current study was conducted to report the short-term clinical outcome of the THA by using Minihip neck preserving stem.
METHODS:
In the current study the short-term clinical outcomes of the patients in the patients who were treated by Minihip THA is analyzed. All patients were evaluated via Hip Disability and Osteoarthritis Outcome Score (HOOS). In addition we explored the effect of obesity on the perceived difficulty of surgery performance. A multinomial logistic regression was used in addition to a multivariate repeated ANCOVA was performed to determine significance of the demographics (i.e., BMI, Height, Weight, Age, and Gender). The signed consent was obtained from each participant.
RESULTS:
26 of the patients reported their symptoms to evaluate the HOOS (20 male, 6 female, Age 61.7 ± 8.5 years and BMI of 27.5 ± 3.88). Six patients demonstrated obesity (BMI>30). Post-operative data were collected at a mean followup time of 3 months. The results indicated significantly higher HOOS in individuals during postop depicting better quality of life (F(1, 25) = 186.695, p < .001), lower pain (F(1,25) = 249.317, p < .001), and higher activity level (F(1,25) = 202.233, p < .001). The increase in the performance of the patients however was not affected by the obesity of the individuals. We have also explored the effect of BMI on the difficulty of the surgery perceived by the surgeon and found that the surgeries were more difficult in obese patients (p = .023).
CONCLUSION:
In this pilot study we have demonstrated that Minihip has the potential to exhibit excellent short-term clinical outcome in THA. In our study all individuals reported better quality of life after receiving the surgery. Future study should be conducted on comparing the differences in the outcome of the THA between commonly used implants and neck preserving stems.
