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Published 4/1/2014
Maureen Leahy

Study Examines Outcomes of Hamstring Autograft and Tibialis Posterior Allograft for ACL Reconstruction

Study data presented at the AAOS Annual Meeting in New Orleans revealed that more than 80 percent of all grafts used in anterior cruciate ligament (ACL) reconstruction in a young athletic population were intact and had maintained stability at 10-year follow-up. However, tibialis posterior allograft ACL reconstructions failed at a rate more than three times higher than hamstring autograft reconstructions.

“Although patellar tendon autograft has been considered the ‘gold-standard,’ the use of soft tissue grafts has become more common due to improved techniques for femoral and tibial fixation,” wrote the authors. “Specifically, the hamstring autograft has increased in popularity due to comparable clinical outcomes, decreased anterior knee pain and kneeling discomfort, lower donor-site morbidity, and decreased potential injury to the extensor mechanism.”

“The use of allografts for ACL reconstructions in young athletes is controversial,” said presenter Craig R. Bottoni, MD, of Tripler Army Medical Center, Honolulu. “Our study was unique in that it evaluated the long-term success of two types of grafts commonly employed in ACL reconstructions: hamstring autograft and tibialis posterior allograft.”

Level I evidence
The researchers conducted a prospective randomized clinical trial involving 99 patients (100 knees) with acute ACL rupture who were seen at their military medical center from June 2002 through August 2003. Knees were randomized into either hamstring autograft or tibialis posterior allograft for their ACL reconstruction.

The mean age in both groups was 29 years; most (87 percent) patients were male and most (95 percent) were on active duty, with sports the most common mechanism of injury. All allografts were from a single certified tissue bank, aseptically processed and fresh frozen without terminal irradiation. Concomitant meniscal and chondral pathology, microfracture, and meniscal repairs performed at the time of reconstruction were similar in both groups.

“We attempted to eliminate as many variables as possible in designing the study,” Dr. Bottoni explained. “All surgeries were performed either by me or Eric L. Smith, MD, and all reconstructions were via the exact same technique. The physical therapists were blinded to the graft choice, and all patients followed the same therapy and postoperative rehabilitation protocol.”

Preoperative and postoperative assessments were performed via physical examination and/or telephone or internet-based questionnaires. Subjective outcome measures included the Single Assessment Numeric Evaluation (SANE) score, Tegner Activity Score, and the International Knee Documentation Committee (IKDC) Subjective Knee Form. The primary outcome measures were graft integrity, subjective knee stability, and functional status.

Long-term results
“Amazingly, we were able to contact or examine nearly all the patients in the study at a minimum of 10-year follow-up. Unfortunately, 2 patients had died, 1 required bilateral knee replacements, and only 1 was lost to follow-up,” saidDr. Bottoni.

In the remaining patients, 17 graft failures were identified—13 allograft and 4 autograft—requiring revision ACL reconstruction. No differences were found in the SANE, Tegner, or IKDC scores in the patients with intact grafts.

“The hamstring autograft demonstrated a better survival rate than the tibialis allograft at latest follow-up—91.7 percent vs. 73.5 percent, respectively (P = 0.03). Interestingly, the activity level and subjective outcomes were identical in patients with intact grafts; that is, both types of grafts provided sufficient stability to enable patients to return to high levels of military and athletic activities,” Dr. Bottoni said.

With respect to the timing of the failures, Dr. Bottoni added, “The 2-year results showed about the same proportion of graft failures, with the other half of the total number of failures occurring in the next 8+ years.”

He concluded, “Our study found that in comparing a hamstring autograft with a tibialis posterior allograft for ACL reconstruction, long-term survival was better in the autograft group.”

Dr. Bottoni’s coauthors of “Autograft vs Allograft ACL Reconstructions: A Prospective, Randomized Clinical Study with Minimum 10-year Follow-up” are Eric L. Smith, MD; Sarah G. Raybin, BA; CPT James S. Shaha, MD; Steven H. Shaha, PhD, DBA; Col. John M. Tokish, MD; and CDR Douglas J. Rowles, MD.

Disclosures: Dr. Bottoni—Arthrex, Inc; Musculoskeletal Transplant Foundation. Dr. Smith—Arthrocare; DePuy, A Johnson & Johnson Company; Omni Life Science; Pfizer; Stryker. Dr. Tokish—Journal of Shoulder and Elbow Surgery; Orthopedics Today. Dr. James Shaha, Dr. Steven Shaha, Dr. Rowles, and Ms. Raybin—no conflicts.

Maureen Leahy is assistant managing editor of AAOS Now. She can be reached at leahy@aaos.org

Bottom Line

  • The use of allografts for ACL reconstructions in young athletes is controversial.
  • This prospective randomized trial compared hamstring autograft and tibialis posterior allograft from a single certified tissue bank, aseptically processed and fresh frozen without terminal irradiation.
  • At 10-year follow-up, 80 percent of all grafts used were intact and had maintained stability.
  • However, hamstring autograft demonstrated a better survival rate than that of the tibialis posterior allograft.

Additional Information
Presentation Abstract