Poor Functional Outcome Following Total Knee Replacement Due to Underlying Lumbar Canal Stenosis: A Case Report.

The current era of orthopedic practice is marked by increasing subspecialization. Many surgeons concentrate primarily on conditions within their specific area of expertise, which can inadvertently narrow their clinical perspective. As a result, patients may not always be evaluated holistically, and this limitation can lead to the misdiagnosis of the underlying primary condition. Total knee replacement (TKR) is an effective treatment for advanced osteoarthritis; however, persistent postoperative lower limb pain may indicate an alternative diagnosis. Pre-existing lumbar canal stenosis (LCS) is one common cause. Overlapping symptomatology between knee pathology and spine problems can lead to misdiagnosis and suboptimal surgical outcomes. We report a 59-year-old woman with bilateral lower limb pain for two years, worsening over the preceding three months. She underwent bilateral TKR for radiologically confirmed severe osteoarthritis in an arthroplasty center but continued to experience disabling leg pain and poor functional improvement despite structured rehabilitation. Evaluation at our spine clinic revealed neurogenic claudication with limited walking tolerance, preserved prosthetic alignment, and significant stiffness of both knees. Magnetic resonance imaging (MRI) of the lumbar spine demonstrated severe L4-L5 LCS. Following lumbar decompression surgery, the patient experienced substantial relief of leg pain and neurogenic symptoms, enabling improved participation in knee rehabilitation. This case illustrates how unrecognized LCS can contribute to persistent postoperative symptoms and poor functional recovery following TKR. Lumbar decompression effectively resolved the patient's neurogenic symptoms, confirming spinal pathology as the primary cause of persistent pain rather than prosthetic complications. Persistent lower limb pain after TKR warrants a thorough evaluation of other causes of pain including lumbar spine pathology. Early recognition and treatment of LCS are essential to optimize postoperative outcomes and prevent prolonged dysfunction. Spine assessment should be integral to the preoperative planning of TKR especially in patients with atypical or disproportionate symptoms.