Osteonecrosis of the Knee after Arthroscopic Partial Meniscectomy
A 50-year-old male visited our clinic with a major complaint of pain in the right knee that had started five days earlier. He had no history of trauma and complained of a pulling sensation behind the right knee and giving way symptoms when walking down stairs. The patient had been working as a medical technician carrying gurneys for 21 years and had no significant medical history or history of trauma, alcohol abuse, and intra-articular steroid injections. Physical examination revealed tenderness over the medial femoral condyle but no edema. The range of motion and lower limb alignment were normal. McMurray's test was negative, joint instability was not present, and early radiography was normal (), Magnetic resonance imaging (MRI) showed evidence of posterior meniscal tear without any chondral or bone marrow damage (). Surgical treatment of the posterior tear of the medial meniscus was performed. A complex tear of the posterior horn of the medial meniscus and an International Cartilage Repair Society grade II cartilage lesion (lesions involving <50% of the total cartilage thickness) in the medial femoral condyle were observed with arthroscopy (). Surgery was performed under spinal anesthesia while maintaining 70 mmHg of pressure with an arthroscopy pump, and a tourniquet was not used. Partial meniscectomy was performed with a basket forceps and a shaver without using a razor or radiofrequency device and the cartilage damage was treated with debridement. The total surgical time was approximately 20 minutes.\nThe patient complained of pain at the second postoperative week, which was managed with medication. At the sixth postoperative week, the patient felt severer pain and had the greatest difficulty in walking with straight legs, for which an increased dose of anti-inflammatory analgesics was administered. At the 12th postoperative week, an MRI scan was performed because the pain increased except for temporary relief.\nThe MRI scan revealed cartilage delamination of the medial femoral condyle that exhibited a low intensity signal on the T1-weighted image and a high intensity signal on the T2-weighted image (). Since the symptoms deteriorated during three months of medication therapy, another MRI examination was performed six months postoperatively, which showed more extensive cartilage delamination and cyst formation. An MRI scan taken nine months postoperatively showed an enlarged cyst, increased swelling around the bone, and severe cartilage delamination, all of which were the symptoms of osteonecrosis (). Thus, unicompartmental knee arthroplasty was performed (). Currently, at six months after surgery, the patient has been pain-free and returned to work.