Abstract
Objective: In patients with hip fracture we have frequently identified postoperative knee joint pain, which may adversely affect the rehabilitation outcome. The purpose of our study was to clarify the relationship between knee osteoarthritis (OA) and postoperative knee pain after hip fracture.
Materials and Methods: Thirty four patients with acute hip fracture were enrolled in the study, and divided into two groups; patients with (OA group) or without (non-OA group) radiographic knee osteoarthritis. Radiographic knee osteoarthritis was defined as a severity greater than grade 2 using the Kellgren-Lawrence Grade. We compared the age and number of patients with intertrochanteric fracture, knee effusion at the time of surgery, and postoperative knee pain during rehabilitation between the 2 groups. In addition, synovial fluid was collected with syringes in 10 randomly selected with knee effusion at the time of surgery, and one drop of synovial fluid from each patient was analyzed for calcium pyrophosphate dihydrate crystals using a compensated polarized light microscope.
Results: Eighteen of the 34 patients were allocated to the OA group. Patients in the OA group were significantly older than those in the non-OA group. Seven patients in the OA group and 11 in the non-OA group were diagnosed as having a femoral neck fracture (P=0.16). Twelve patients in the OA group and 4 in the non-OA group had knee joint effusion on the hip fracture side at the time of surgery (P=0.037). Five patients in the OA group and 3 in the non-OA group had postoperative knee pain during rehabilitation (P=0.69). Most patients with postoperative knee pain in both groups had knee effusion at the time of surgery. In addition, calcium pyrophosphate dihydrate deposit (CPPD) was seen in 8 of 10 patients.
Conclusion: In many patients, knee effusion was found at the time of surgery, and this phenomenon basically originated from CPPD. Postoperative knee pain after hip fracture could be caused by CPPD even if the patients did not have radiographic knee osteoarthritis.
