Lower Limbs Alignment in Patients with a Unilateral Completely Dislocated Hip

Area of Science:

• Orthopedics
• Biomedical Engineering
• Rheumatology

Background:

• Severe hip osteoarthritis frequently leads to secondary knee joint osteoarthritis.
• The relative importance of contracture versus leg length discrepancy in influencing knee alignment remains unclear.

Purpose of the Study:

• To investigate lower limb alignment patterns in patients with unilateral completely dislocated hips (Crowe IV).
• To determine the prevalence of specific deformities like "windswept deformity" and "long leg arthropathy" in relation to hip dislocation severity.

Main Methods:

• Study included 48 hips in 48 patients with unilateral Crowe IV hip dislocation, divided into Crowe IVa (with pseudo-articulation) and Crowe IVb (without pseudo-articulation) groups.
• Lower limb alignment was classified based on the femorotibial angle: varus (≥176°), neutral (170-175°), and valgus (≤169°).

Main Results:

• "Windswept deformity" (valgus on the affected side, varus on the unaffected) occurred in 12.5% of patients (18.2% in Crowe IVa, 7.7% in Crowe IVb).
• "Long leg arthropathy" (valgus alignment on the unaffected side) was observed in 6.3% of patients, exclusively in the Crowe IVa group (13.6%).

Conclusions:

• Patients with Crowe IV hip dislocation often exhibit varus alignment on the unaffected lower limb.
• "Windswept deformity" was present in both Crowe IV subgroups, but "long leg arthropathy" was specific to the Crowe IVa subgroup.