Thirty-seven patients (17 females, 20 males) underwent resection of an IBSN neuroma at our institution between the years 2001 and 2015. Among them, 25 patients were available to answer a follow-up self-reported functional outcome questionnaire. The average age was 38.9±12.5 years and average follow-up from surgery was 94±52.9 months. Injury to the IBSN resulted from a previous orthopedic surgery in 20 patients, in 13 of them this was an arthroscopic surgery of the knee, 5 underwent anterior cruciate ligament (ACL) reconstruction and 4 open reduction and fixation of a fracture. Three patients had undergone previous vascular surgery involving either saphenous vein harvesting or a femoral-popliteal arterial graft. Six patients were post resection of a tumor from the area of the distal femur or proximal tibia. These included two osteochondromas, one schwannoma, one benign fibrous histiocytoma, one glomus tumor and one peripheral Schwannoma.
In the remaining 8 patients, a precipitating trauma or skin infection to the lower limb caused the initial nerve injury consisting of a blunt trauma to the leg in 5, skin laceration in 2 patients and Erysipelas in one patient. All patients had failed a trial of non-operative treatment for a minimum of 6 months and 20 patients reported undergoing numerous surgeries at the knee area prior to their referral to our institute. Six patients were after two prior surgeries, 3 had had three and 1 patient had undergone 4 prior knee surgeries. Three of these patients, also reported undergoing a prior unsuccessful resection of an IBSN neuroma. Table 1.
Preoperative sensory NCV study focusing on the infrapatellar nerve was done in 27 patients. The NCV study was able to locate a conduction impairment of the saphenous nerve and the IBSN in 89 % of the cases. Additionally, ultrasound imaging of the nerve was done in a subgroup of 15 patients, of them, only in 7 patients the neuroma was identified prior to surgery. All patients were operated at a same day surgery service and were released from the hospital in the evening of the surgery. No complications were noted during surgery. One patient developed a postoperative wound infection that was treated by surgical wound revision and an antibiotic treatment.
Following surgery, statistically and clinically significant improvement in pain was seen in 80% of patients. The NRS pain score improved from 9.4 ±1.3 to 5.1 ±3.3 (P<0.01). Nevertheless, 52% of patients reported that they continued to use analgesic treatment regularly and 36% continued pain clinic treatments.
Five patients (20%) underwent revision surgery in our institute due to recurrent knee pain. The time interval between the primary and the revision surgery was 21.4±17.1 months.
The EQ-5D functional score improved from 10.48±2.33 to 7.84±2.19 (P<0.01). Overall patient reported satisfaction from the surgical results was good in 72% of patients. Table 2.
Using regression analysis, the following variables were found to correlate with favorable pain improvement: younger age, male gender, higher level of self-reported anxiety and depression status, preoperative pain level and mobility limitations. A non-favorable outcome was correlated with the following variables: high number of prior surgeries, prior resection of a IBSN neuroma and higher level of limitations in activity and self-care (p<0.001). Figure 2
Favorable functional outcome improvement was correlated with younger age, male gender, high level of preoperative anxiety and depression. Non-favorable improvement was correlated with high number of prior surgeries, and higher levels of activity limitation (p=0.001). Figure 3
Other variables including: preoperative pain, limitations in mobility and self-care limitation, side of surgery and prior surgery for resection of a neuroma were not associated with improvement in patients’ functional outcome.