A 15-year-old adolescent patient presented with chronic anterior knee pain and persistent gait dysfunction despite normal knee imaging. She reported a 2-year history of right-sided pain and a varus-hyperextension gait pattern with an audible clunk during ambulation that mimicked knee subluxation, resulting in significant functional limitations. She denied prior trauma and was no longer able to participate in sports.
Initial evaluations by multiple orthopedic surgeons did not identify the cause for her symptoms. Magnetic resonance imaging and plain radiography of the knee demonstrated no ligamentous, intra-articular, or structural abnormalities, and conservative management, including physiotherapy and bracing, failed to improve symptoms. On physical examination, right hip internal rotation was 85°, external rotation was 30°, the patient exhibited a right squinting patella, and rotational profile measurements were abnormal. Although coronal alignment appeared normal on radiographs, computed tomography and EOS imaging demonstrated significant axial malalignment, including 44° of femoral anteversion and 35° of external tibial torsion.
Three-dimensional gait analysis provided additional insight, identifying dynamic multiplanar abnormalities not apparent on static imaging. These included excessive knee varus and hyperextension during stance, abnormal external knee rotation, and altered hip and knee joint moments. Based on the convergence of clinical findings, rotational imaging, and gait analysis, the researchers concluded that lower extremity torsional abnormalities (LETA) were the most plausible cause of the patient’s symptoms. However, the investigators noted that their assessment could not establish a definitive causal relationship.
Given persistent pain, functional limitation, and failure of nonoperative management, the patient underwent combined femoral and tibial torsional osteotomies. Surgical correction aimed to restore a more normal torsional arc and knee-forward position during ambulation. At 2 years of follow-up, the patient’s pain and subluxation had resolved. Objective assessments showed normalization of hip rotation, foot progression angle, bimalleolar axis, and gait mechanics on repeat three-dimensional gait analysis. Patient-reported outcome measures, including the Pedi-International Knee Documentation Committee and Pediatric Outcomes Data Collection Instrument scores, also demonstrated clinically meaningful improvement.
The researchers noted that LETA remain an underrecognized cause of anterior knee pain and atypical gait patterns, particularly in adolescents with normal intra-articular imaging. In this patient, three-dimensional gait analysis demonstrated varus and hyperextension during stance in the setting of femoral and tibial torsional deformity.
“This case enhances the understanding of LETA by linking static torsional deformity with compensatory movement patterns, emphasizing the need for clinicians to maintain a high index of suspicion for rotational malalignment in patients with anterior knee pain and atypical gait mechanics,” noted lead author Nour Kabbes, MD, of the McGill Faculty of Medicine, Montreal, Quebec, Canada, and colleagues.
The researchers reported no conflicts of interest.
Source: JBJS
