Anatomy of the proximal femur as seen with three-dimensional magnetic resonance imaging

Morphometric analysis of all 24 hip muscles: A cadaveric study of 18 hip specimens with proposal of a new classification of muscles

PURPOSE

There are few papers investigating the morphometry of hip muscles and reporting either a single muscle or a group of synergistic muscles. With the development of hip joint simulation, hip arthroplasty implants, and gait analysis, a set of biometric data covering all the muscles that act on the hip joint is needed.

METHODS

Using a rigorous dissection process on 18 cadaveric hips, measurements of all 24 hip muscles and bone parameters were conducted. We measured the following: (a) total femur, femoral shaft, and neck lengths, (b) total muscle lengths, (c) intra-muscular and extra-muscular (free) tendon lengths, (d) bone angles, (e) muscle pennation, sagittal, and frontal angles, (f) muscle weight, (g) muscle volume, (h) muscle cross-sectional area, and (i) and bending moment. Data on more than 12,000 morphometric or anatomical parameters were collected. Correlation values between bone variables, muscle variables, and in-between muscle variables were computed. Based on their compliance, muscles were classified using the ratio of belly length over the sum of intra-muscular and free tendons.

RESULTS

Values of the neck, shaft, and total femur lengths were highly correlated in relation to each other. The long muscles and the pelvitrochanteric muscles were highly correlated with femoral bone lengths. The proximal and distal intra-muscular tendon lengths were correlated to the total muscle length for all long muscles, independently of free tendon (extra-muscular) or muscle belly lengths. A very significant correlation was found between muscle weight variations among specimens. Three groups of muscles were identified based on their compliance.

CONCLUSION

This is the first comprehensive anatomical morphometric study which includes all the 24 muscles acting on the hip joint. It generates a unique anatomical dataset comprising all necessary data for musculoskeletal modeling and arthroplasty implants of the hip joint. A new muscle classification was proposed based on compliance where muscles of the same group would exhibit similar compliance and functional anatomy.

A computertomographic study on the congruence of the hip joint

This study describes investigations into the appearance of intra-articular spaces of hip joints. In CT scans of cadaver hip joints in the supine position an increased intra-articular space was found dorsally, while in the prone position the same hip joint showed an increased intra-articular space ventrally. It is assumed generally that the gap between the bone ends seen on plane X-rays represents the cartilage, but this study indicates that there may in fact be a space between the cartilage surfaces in the unloaded joint.