Partial isolated tear of the popliteus tendon following an in-car traffic accident: A rare cause of knee pain: A CARE-compliant case report

RATIONALE: Lesions caused by traffic accidents are often microscopic and minimal; therefore, their diagnosis can be easily overlooked. Moreover, when it is a rarely reported type of lesion, it can be even more easily undiagnosed. Isolated popliteal injuries are uncommon and have rarely been reported. PATIENT CONCERNS: In this case study, we describe a right partially isolated popliteus tendon rupture that was undiagnosed for 2 years in a patient with posterior knee pain after an in-car traffic accident. A 49-year-old female patient presented with right knee pain that had persisted for 2 years and was initiated after an in-car traffic accident. The patient’s right knee pain aggravated while standing and walking. Six months after the accident, her pain was confined to the posterolateral aspect of the knee and subsequently spread throughout her right knee. The pain score was 4 on a numerical rating scale. Physical examination revealed tenderness in the posterolateral corner of the right knee. Additionally, right knee pain was reported in the terminal range of knee flexion during the passive range of motion test. Radiographs of the right knee showed normal findings. DIAGNOSES: A T2-weighted proton density sagittal and coronal knee magnetic resonance imaging revealed a partial-thickness tear with intrasubstance ganglion cysts at the musculotendinous junction of the popliteus tendon. No other abnormalities were observed in the patient. INTERVENTION: Conservative treatment involved strengthening exercises and functional rehabilitation programs. OUTCOMES: Six months later, the knee pain almost completely subsided. LESSONS: Musculoskeletal injuries caused by traffic accidents are frequently overlooked. Therefore, a detailed examination should be conducted for an accurate diagnosis. Clinicians should consider the possibility of popliteal tendon injuries in patients with posterior knee pain.