2015 ISAKOS Biennial Congress ePoster #1326
Incidence and Characterization of Injury to the Infrapatellar Branch of the Saphenous Nerve after ACL Reconstruction: A Prospective Study
Steven B. Cohen, MD, Media, PA UNITED STATES
Russell Flato, BA, Philadelphia, PA UNITED STATES
Jocelyn M. Wascher, BA
Matthew Salminen, MS, Philadelphia, PA UNITED STATES
Daniel O'Brien, BA, Philadelphia, PA UNITED STATES
Ryan A. Watson, BA, Philadelphia, PA UNITED STATES
Christopher C. Dodson, MD, Philadelphia, PA UNITED STATES
John P. Salvo Jr., MD, Marlton, NJ UNITED STATES
Fotios P. Tjoumakaris, MD, Egg Harbor Township, NJ UNITED STATES
Paul Marchetto, MD, Philadelphia, PA UNITED STATES
Michael G. Ciccotti, MD, Philadelphia, PA UNITED STATES
The Rothman Institute of Orthopaedics at Thomas Jefferson University, Philadelphia, PA, USA
FDA Status Not Applicable
Summary: A prospective evaluation of 218 patients undergoing ACL reconstruction was conducted to determine the incidence of postoperative sensory deficits around the knee and characterize the changes in these deficits over time.
The infrapatellar branch of the saphenous nerve is commonly injured in anterior cruciate ligament reconstruction (ACLR) causing sensory deficits around the knee. The incidence of post-operative sensory deficit has varied widely in previous studies, and the effects of time and type of graft on the severity of numbness have not been reported.
Hypothesis/Purpose: The primary purpose of this prospective study was to determine the incidence of patient reported sensory deficits around the knee following ACLR. The secondary purpose was to determine if sensory deficits caused by intraoperative injury present at 6 weeks changed in severity and total area after 6 months and 1 year postoperatively in addition to determining how graft type affects numbness severity.
Two-hundred and eighteen patients that underwent ACLR with or without meniscal repair were prospectively enrolled. Variables for each patient included: type of graft, direction of tibial incision, number of portals, and length of surgical incision. The grafts used were categorized into three types: Allograft, hamstring autograft (HS), or patella tendon autograft (BTB). At 6 weeks, patients completed a questionnaire to ascertain any sensory deficits over their knee. Patients rated their sensory deficit on a scale from 0-10 (“0” = no deficit; “10” = complete lack of sensation) and shaded areas on a picture of a knee split into nine rectangular segments (3 by 3 grid) to determine the location of any numbness. Patients completed the same questionnaire at 6 months and 1 year postoperatively. Any patient who reported no numbness at 6 weeks or 6 months was considered to have completed the study. All patients with numbness at any time point were followed for a minimum of 1 year. A mixed effects linear regression model was used to identify variables that were predictors for the patient-reported severity of numbness.
Overall, 68.8% (150/218) reported numbness at six weeks, 50.0% (97/194) at six months, and 42.2% (78/185) at one year. Twenty-four patients were lost to follow-up at six months, and nine were lost to follow-up at one year despite repeated attempts to contact them. The most common location of numbness was along the inferolateral aspect of the knee. The mean numbness rating for allografts was 2.89 +/- 0.29 (mean +/- standard error) at 6 weeks, decreasing to 1.66 +/- 0.24 at 6 months and 1.36 +/- 0.25 at 1 year for oblique and vertical incisions combined. A statistical model, controlling for time and incision direction, indicated that HS patients were 1.43 +/- 0.45 points higher than allograft patients across all time points, and BTB patients were 1.15 +/- 0.43 points higher than allograft patients. Time had a negative impact on the patient reported severity of numbness score for all graft types. At 6 months this effect was -1.31 +/- 0.16 and at 1 year, -1.70 +/- 0.17. The mean number of segments decreased slightly with time, down by 0.28 +/- 0.07 at 6 months (p=<0.001) and 0.53+- 0.07 at 1 year (p=<0.001).
Sensory deficits after ACLR follow the direction of the infrapatellar branch of the saphenous nerve. Patients who underwent ACLR with allograft were less likely to develop sensory deficits compared to BTB or HS. In addition, sensory deficits in allograft patients were on average, less severe. Surprisingly, there was no significant difference in numbness between HS and BTB grafts. Surgeons should counsel their patients that sensory deficits are common postoperatively after ACLR, but that this sensory disturbance is likely to dissipate with time.