Study cohort
Patients with diffuse PVNS, as confirmed on pathological evaluation, who underwent complete arthroscopic synovectomy and external-beam radiotherapy between May 2009 and January 2016, were enrolled into the study. All patients gave informed written consent and the study was approved by the Ethical Committee of Zhongnan Hospital of Wuhan University. The inclusion criteria were: clinical symptoms and MRI findings of diffuse PVNS; postoperative pathologic confirmation of primary diffuse PVNS; no major degenerative changes of the knee. The exclusion criteria were: diffuse PVNS with extra-articular extension into bone and soft tissue or need open surgery; recurrent diffuse PVNS; PVNS in any other joints than the knee.
18 patients were enrolled in total, 8 were men and 10 were women. The mean age of the patients was 38.3 years (19 to 63). Presenting symptoms were mainly spontaneous swelling, diffuse nonspecific knee pain, and a decreased range of motion. X-rays of the affected knee were performed to detect and exclude other pathologies such as osteoarthritis. All patients were subjected to an MRI scan for better preoperative evaluation (Figure 1). All of the procedures described were performed by the same surgical team comprising all the authors. The team not only provided preoperative and perioperative care to the patients but also participated in postoperative recovery.
Surgical techniques
The patient was supine and a thigh tourniquet was used under spinal anaesthesia. A 30° arthroscope (Linvatec) and a 5.5mm motorized shaver were routinely used. Standard anteriolateral and anteriomedial portals were made. After the examination of the anterior compartment, the complete synovectomy was done including anteromedial and medial gutter, notch area, anterolatearal and lateral gutter, and medial and lateral submeniscal area (Fig. 2). When the popliteal tendon hiatus area was difficult to access, extreme lateral portal was established to facilitate the synovectomy; Then two posteromedial portals were created to finish the synovectomy of posteromedial compartment; the high portal 2.5 cm to 3 cm above the joint line and the low portal level with the joint line. The arthroscope was introduced through the high posteromedial portal, providing a clear view. A power-shaver was inserted through the low posteromedial portal to debride the synovium of posteriomedial compartment (Fig. 3). Then the mid-third of the posterior septum was removed until the posteriolateral compartment could be visualized clearly. Moving the arthroscope through the posterior septum, the posterolaral portal was made and the posterolateral synovectomy was accomplished (Fig. 4). Finally, the suprapatellar pouch region was completely debrided and lateral suprapatellar portal was used if needed. Arthroscopic electroablation was done just when an oozing vessel seen. An intra-articular suction drain was sustained 24 hours after surgery. The suture was removed from the surgical wounds around 2 weeks after the operation.
Rehabilitation protocol
The patients began physical therapy after removing the drain. Straight leg raising and ankle pump were started from the first post-operative day. Passive range of motion exercises with a continuous passive motion was done in the first postoperative two weeks, and then changed to active exercises. Weight bearing was allowed according patient’s tolerance. Therapeutic goals were set to achieve maximum range of motion, restore quadriceps muscle strength, and decrease swelling and pain in the early postoperative period.
Radiotherapy
In 4-6 weeks postoperatively, all patients underwent local adjuvant radiotherapy applied with a 6-MV linear accelerated photon beam. The total dose was 20 Gy, which was performed 10 times, once every other day. Fractioned irradiation doses were delivered to the anterior and posterior fields of the operated knee.
Follow-up and evaluation
After radiotherapy, patients were re-examined MRI and then re-evaluated by the same radiologist every 6 months. Each patient was evaluated before treatment and at the final follow-up visit, the evaluation criteria used in this study was according to Ogilvie-Harris [16]. The criteria comprise four parameters: articular pain, synovitis or articular effusion, range of motion, and functional ability. Each of the four parameters is graded on a scale of 0 to 3 points. To globally evaluate the results of the combined treatment, we calculated the arithmetic average of the scoring obtained by the various parameters considered in homogeneous classes of treatment. The patient's condition was rated as excellent (scores between 10 and 12), good (scores between 7 and 9), fair (scores between 4 and 6), or poor (scores between 0 and 3). Because the parameter of functional ability in this evaluation criteria is non-specific, we used the International Knee Documentation Committee (IKDC) [17] scores to evaluate the knee function. In the process of the follow-up, recurrence case was diagnosed on the basis of renewed onset of clinical symptoms and MRI screening, and was confirmed pathohistologically.
Statistical analysis
The preoperative and final follow-up scores of Ogilvie-Harris criteria and IKDC scores were statistically analyzed using SPSS 17.0 software (SPSS Inc., Chicago, Illinois). The Mann–Whitney U test was used compare the IKDC scores. A p value < 0.05 was considered statistically significant.