gms | German Medical Science

Objectives: Leg length inequalities (LLIs) are a common orthopaedic condition that can lead to temporary or even permanent changes in pelvic position and spinal posture causing musculoskeletal disorders, such as lower back pain, functional scoliosis, gait disorders and hip/knee osteoarthritis. Usually, minor LLIs can be left untreated since they can be compensated for by the patients; however, LLIs of 2 cm and more should be treated as they can lead to clinical symptoms. So far, the exact amount of LLIs that is clinically relevant is still unknown, therefore we seek to compare and study the direct effects of LLIs >=2cm versus < 2cm on the pelvic position and spinal posture.

Methods: We included 32 patients (10 females, 22 male) with real LLIs of >=2cm (mean: 2.72cm; n=10) and compared their pelvic position and spinal posture to patients with LLIs <2cm (mean: 1.24cm; n=22). All patients were measured with a surface topography system (Diers International GmbH) during standing and while walking on a treadmill. To compare patient groups, we used Student t-tests for independent samples.

Results and Conclusion: During standing, we found significantly higher pelvic obliquity in patients with LLI >=2cm (p=0.045). However, there were no differences found for pelvic torsion and inclination between the groups (p=0.79, 0.35). No differences were measured for spinal posture (kyphotic and lordotic angle, lateral deviation, surface rotation) between patients with LLIs >2cm and < 2cm. During walking patients with LLIs>=2cm compensated for their difference in leg length so that we did not find any differences between the two groups in terms of spinal posture and pelvic position (p=0.06-0.706).Significant differences were only shown for pelvic obliquity in the midstance phase of the longer leg (p=0.023).

The results of our study suggest that relevant LLIs of >=2cm mostly affect pelvic obliquity and do not lead to significant alterations in the spinal posture during a standing trial. To our surprise, patients with >=2cm LLIs can even further compensate for their LLIs while walking on a treadmill, since we did not find any differences between the 2 groups. This study shows for the first time that LLIs >=2cm can still be compensated; however, we do not know if the compensation mechanisms may lead to long-term clinical pathologies.