Bone marrow edema (BME) of the knee is often seen in MRI and has several different underlying pathologies. The correlation between disorders of the knee joint and a BME is not fully understood yet. Persistent or progressive postoperative pain and/or functional impairment after arthroscopic partial meniscectomy is still a common phenomenon in many patients. The aim of this prospective clinical trial was to find a correlation between the typical postoperative disorders and BME in MRI and to identify possible therapeutic consequences.
150 consecutive patients with preoperatively diagnosed meniscus defects and without any previous operation and no BME underwent arthroscopic partial meniscectomy. A two- to three-day resting period was established postoperatively. The patients then rapidly returned to full weight bearing. No crutches were used. As a standard analgetic, we used diclofenac 50 mg three times a day for three days. Clinical control and removal of the sutures was performed on day 8 postoperatively. The patients' pain status was controlled by using the IKDC score and the Visual Analogue Scale (VAS) before and six weeks after surgery. Six weeks after the surgical intervention, the patients underwent a standardized physical examination and, if there was ongoing functional impairment or discomfort of the knee, a new MRI was performed. However, if patients showed signs or severe discomfort prior to the end of the six-week observation period an MRI was scheduled earlier.
Postoperatively 11 of the 150 patients (7,3 %) developed progressive discomfort with pain during stress and also by night. A postoperative BME in the MRI was seen in all 11 symptomatic patients (100 %). We saw a significant correlation to women older than 70 years (p < 0.05). The VAS score six weeks after arthroscopy was significant reduced in the group without any clinical symptoms (2.63 ± 2.83 after arthroscopy and 4.27 ± 2.36 MW ± SEM before arthroscopy) compared to the group with proven BME (5.09 ± 2.74 before arthroscopy and 5.27 ± 2.57 MW ± SEM after arthroscopy; p < 0.05). The IKDC score was significantly enhanced in the clinical asymptomatic group: 58.1 ± 10.53 in comparison to the patients with proven BME, with 35.32 ± 13.2 MW ± SEM (p < 0.05).
Patients with clinical symptomatic BME showed a significantly higher VAS score and a significantly lower IKDC score postoperatively. Therefore, in patients with postoperative discomfort, a prompt MRI should be performed and, if a BME is proven, further therapy should be modified.