Surgical treatment outcome of painful traumatic neuroma of the infrapatellar branch of the saphenous nerve during total knee arthroplasty

BACKGROUND Development of infrapatellar saphenous neuroma(ISN)is a well-recognized reason for knee pain following total knee arthroplasty(TKA).So far,very few studies have addressed the development of painful ISN after TKA and its impact on functional outcome and patient satisfaction.AIM To present the results of surgical treatment for ISN after primary TKA,the level of pain relief,and the improvement of knee motion and function.METHODS Fifteen patients(13 women,2 men)with persistent medial pain for more than six months after primary TKA,due to osteoarthritis,underwent surgical excision of ISN.ISN diagnosis was confirmed with the presence of Tinel’s sign along the course of the infrapatellar branch of the saphenous nerve and with pain relief after selective nerve block using local anesthetic.Component loosening,malalignment,instability and infection were excluded systematically in all patients as a source of pain.Pain relief in terms of visual analog scale(VAS),active knee range of motion(ROM),and the Knee Society Score(KSS)for pain and function were evaluated preoperatively and at least six months postoperatively.RESULTS The mean patients’age was 71.3±5.4 years old.The mean interval between TKA and neuroma excision was 10 mo(range,6 to 14 mo),while the mean follow-up was 8 mo(range:6 to 11 mo).All 15 patients experienced almost complete immediate pain relief and resolution of allodynia and hyperesthesia after surgery.Pain on the VAS scale improved from 8.6±1.3 preoperatively to 0.8±0.9 at the final follow-up(P=0.001).KSS pain and function scores were improved from 49.3±5.9 and 62.7±12.8 before surgery to 91.8±4.2 and 75.3±11.3 after surgery,respectively(P=0.001 and P=0.015).Active knee ROM was also increased postoperatively from 96±4 to 105±6 degrees(P=0.001).There were no complications and no further operations required.CONCLUSION ISN should be considered a potential cause of persistent pain following TKA.Neuroma excision not only provides immediate pain relief and resolution of symptoms but may also improve the knee range of motion.

Relationship between different skin incisions and the injury of the infrapatellar branch of the saphenous nerve during anterior cruciate ligament reconstruction

Background After anterior cruciate ligament （ACL） reconstruction, some patients suffered from sensory disturbance around the surgical incision of the leg. This research was aimed to investigate the relationship between the different skin incisions and the injury of the infrapatellar branch of the saphenous nerve （IPBSN） post ACL reconstruction.Methods ACL reconstructions were performed with quadruple hamstring tendon for 60 patients. Sensory disturbance around the skin incision was followed up at an average of 14.5±4.7 months post operation. Among the 60 patients, vertical incision for 35 patients and oblique incision for 25 patients were used for graft taking during ACL reconstruction. The lengths of the incisions were measured. The patients were asked to mark the sensory disturbance zone at follow up time, and then the marked area was measured. The IPBSN of 15 cadaver knees were anatomized. The distance between the IPBSN and the upper edge of the pes anserinus tendon at the middle point of the incision was measured. independent-samples t-test, chi-square and Mann-Whitney tests were used for statistical analyses. Results The patients＇ age （P=0.329）, the follow-up time （P=0.661）, and the incision length （P=0.732） between the two groups had no significant difference. Twenty-three patients （65.7%） in the vertical incision group had IPBSN injury compared with 6 patients （24.0%） in oblique incision group （P=0.002）. The average sensory disturbance area in vertical incision group （（48.0±75.3） cm^2） was significantly larger （P=0.004） than that in the oblique group （（8.4±19.4） cm^2）. The anatomy measurement showed the average distance between IPBSN and the upper edge of the pes anserinus tendon was 0.6 cm at the incision. Conclusions Oblique incision with less risk of damage for IPBSN may be better for graft harvesting in ACL reconstruction. As the IPBSN is so near and parallel to the hamstring tendons, damage to the IPBSN is one of the potential complications for graft harvesting, regardless of the incision used. That＇s why even in the oblique incision group, 24% patients also had sensory disturbance complication.