• Sports Medicine
• Orthopaedic Pediatrics
• Orthopaedic Procedures
• Hip & Knee Conditions Clinical Trials

• Sports Medicine
• Orthopaedic Pediatrics
• Orthopaedics
• Orthopaedic Procedures
• Hip & Knee Conditions
• Orthopaedics Clinical Trials

T. David Luo, MD, Mayo Clinic, Rochester, Minnesota, USA, reported on a study that demonstrated long term deficits in muscle strength when anterior cruciate ligament (ACL) reconstruction was accompanied by femoral nerve blockade (FNB) in pediatric and adolescent patients.

FNB is often used to provide analgesia following ACL reconstructive surgery. Although rare, femoral neuropathy can occur, producing weakness, numbness, and pain. The effect that FNB complications might have on patients ≤ 18 years has been unclear.

The retrospective, matched cohort study compared outcomes at 6 months after ACL reconstructive surgery in 169 pediatric and adolescent patients whose surgery, conducted from 2001 to 2010, involved FNB or did not (control). The nerve blockade was accomplished using 20 to 50 ml of .25% or .5% marcaine under nerve stimulator or ultrasound guidance. Because of revision ACL surgery or prior ipsilateral or contralateral knee surgery, 45 patients were excluded. The remaining 124 patients comprised 62 patients in the FNB group (46 via continuous flow over 48 hours, 16 by single injection) and 62 patients in the control group.

The 6-month outcomes were isokinetic strength and function during slow extension and flexion (both 60° per second), fast extension and flexion (both 180° per second), vertical jump, triple jump, and single leg hop. The return to sports of the patients was also assessed. The cohorts were matched for baseline demographics (Table 1).

Concerning surgical factors, the autograft type in patients who received a FNB was predominantly bone-patellar tendon-bone (69%), with hamstring autograft used in 31% of cases. The control group comprised similar percentages of each graft (66% bone-patellar tendon-bone autograft, 34% hamstring autograft). No differences were evident between the groups concerning concomitant procedures, including meniscus and cartilage repair, the type of anesthesia, or mechanism of injury. Significant differences were evident between the FNB and control groups in terms of tourniquet time (81.61 ± 17.9 vs 92.9 ± 17.2 min; p = .002), operative time (134.2 ± 29.4 vs 155.3 ± 45.1 min; p = .003), and anesthesia time (176.6 ± 29.6 vs 199.5 ± 43.0 min; p = .001).

Diminished isokinetic strength at 6 months, measured as fast and slow extension and fast and slow flexion, was more prevalent in patients who received FNB; these differences were significant for fast extension and for fast and slow flexion. Functional testing at 6 months did not reveal significant differences between the patient groups.

At 6 months, 90% of the patients in the control group and 68% of patients who received FNB following ACL reconstruction were cleared for a progressive return to pre-injury sports activities. The difference between the groups was significant (p = .002). Return to sports adjusted for surgical variables revealed significant associations with tourniquet time (OR, 5.6; p = .005), operative time (OR, 5.3; p = .003), and anesthesia time (OR, 6.7; p = .001).

The study findings indicate an association of FNB and significant isokinetic deficits in knee extension and flexion strength at 6 months postoperatively. In addition, the use of FNB delays patient return to sports activities at 6 months.

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