External rotation strength deficit after hip resurfacing surgery

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Musculoskeletal Rehabilitation

Background:

• Hip resurfacing arthroplasty is an alternative to total hip replacement.
• The posterior surgical approach involves dividing the piriformis tendon and outer hip rotators.
• Assessing the impact of this approach on hip muscle function is crucial for patient recovery.

Purpose of the Study:

• To evaluate the effect of hip resurfacing with a posterior approach on hip muscle function.
• To compare muscle strength and pain between the operated and un-operated sides.
• To determine the extent of strength deficit in hip external rotators post-surgery.

Main Methods:

• A study involving 33 patients (55 years mean age, 73% males) who underwent hip resurfacing via a posterior approach.
• Isometric muscle strength testing of hip external/internal rotators and extensors.
• Hip pain assessment during rest, loading, and strength testing.

Main Results:

• Pre-operative external rotation and leg extension strength were lower on the operated side.
• Post-operatively, external rotation strength decreased by 29% and internal rotation strength increased by 28% on the operated side.
• Three months after surgery, operated side external rotation and leg extension strength were 50% and 26% lower, respectively, compared to the un-operated side. Significant pain reduction was observed.

Conclusions:

• Hip resurfacing provides substantial pain relief.
• A significant strength deficit in hip external rotators remains three months post-surgery.
• Further research into mitigating this strength deficit is warranted.