A Systematic Review of Anterior Cruciate Ligament Reconstructions with Hamstring Autograft in Patients Over 50 Years of Age

Anterior cruciate ligament (ACL) rupture is one of the most
common injuries seen in orthopedic sports medicine with over...


Introduction
Anterior cruciate ligament (ACL) rupture is one of the most common injuries seen in orthopedic sports medicine with over 129,000 occurring every year [1]. Until relatively recently, operative treatment has focused mostly on younger active athletes while older individuals were treated conservatively. Ciccotti et al. have reported an 83% satisfaction rate at final follow-up for older patients with an ACL tear treated conservatively [2]. Despite the high patient satisfaction rate, the authors noted persistent instability on exam in 97% of the patients and a reinjury rate of close to 40%, calling into question the benefit of conservative treatment in this age group. With an ever-increasing number of active individuals and increasing life expectancy, more and more patients are participating in high risk activities for ACL injury well into the later years of life. As a result, there has been an increasing number of studies evaluating the clinical outcomes of ACL reconstruction in older patients [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. While 40 years of age has traditionally been the cut off for older patients, several published case reports have documented satisfactory clinical outcomes in patients in their 70s and 80s [11][12][13][14][15]. Because of this growing evidence, many have advocated for ACL reconstruction (ACLR) regardless of the age of the patient in the absence of advanced degenerative changes in the knee. Despite the positive outcomes of ACL reconstruction in older patients, the ideal graft choice in patients over the age of 50 remains

Search Strategy and Criteria
A literature search was conducted in the PubMed, Ovid, EMBASE, and Medline databases for studies in the English language between January 2000 and March 2020. Keywords used to identify relevant articles included "anterior cruciate ligament" OR "ACL" AND "50" OR "aged" OR "aging" OR "older patient". Filters activated included: clinical trial, comparative study, controlled clinical trial, meta-analysis, multicenter study, observational study, randomized controlled trial, review, systematic reviews, validation studies, humans, and English. The focus was to study the various outcomes reported after ACLR among patients who are 50 years or older and had a hamstring autograft. Studies included prospective cohort studies, retrospective studies, and case series. A cohort of patients over the age of 50 years undergoing ACL reconstruction with a hamstring autograft was the primary inclusion criteria.
Studies that did not have all patients treated with hamstring autograft, expert opinions, nonclinical studies, clinical studies that did not include a cohort over 50 years of age, clinical studies that were primarily centered on arthroplasty and studies in which the primary pathology did not involve the ACL were excluded from the analysis.

Extraction of Data and Synthesis
The primary outcomes were clinical and functional results such as Lysholm score and International Knee Documentation Committee (IKDC) score. These scores were extracted independently (M.M and G.Y) and presented as the mean with range of values listed in parentheses. Both pre-operative and post-operative scores were evaluated when available. To evaluate patient's activity level, the Tegner activity score was used where 0 represented disability because of knee problems, and 10 represented the highest score corresponding to national and international elite competitive sports. Failure rate was also extracted which corresponded to a need for surgical revision due to recurrent ACL tear. The Lachman test and pivot-shift test were also assessed. An exam of 0-1 was listed as negative and 2-3 were listed as positive for both tests.
Patient satisfaction information was also evaluated when listed.

Statistical Analysis
The meta-analyses were carried out using STATA software version 14 (Stata Corp, College Station, TX) and R software version 3.6.3. Heterogeneity was quantified by I2 statistic. A random-effect model was used when significant heterogeneity was detected among studies (p < 0.10, I2 ≥ 50%). The Egger's linear regression test and funnel plots were used to examine the possibility of publication bias due to small-study effects (Figure 1

Study Selection
After application of our inclusion and exclusion criteria using the PRISMA guidelines, our initial search yielded 5,248 articles for consideration on PubMed and 10,020 on Ovid databases ( Table 1).
The selected articles were then filtered by abstract for relevance, and 34 studies were identified. After a thorough full-text review, 17 articles were identified that contained only patients aged over 50 years but, these were further filtered to 6 studies, which only contained patients treated with a hamstring autograft.

Study Characteristics and Quality
The six studies identified were English language articles with 3 retrospective case studies, 2 retrospective cohort study, and 1 prospective cohort series. These studies aggregated to 167 knees with 167 hamstring autograft ACLR.

Patient Demographics
The minimum and maximum reported mean age was 50 and 71 years respectively (

Discussion
This systematic review provides significant insights into the Patients also appeared to be highly satisfied with their graft choice and the patient satisfaction rate was reported to be 100% in both studies that included this metric [13,14]. Physical exam findings were reported in 87 patients and 95% were found to have a stable knee with a negative pivot shift and Lachman exams.
Interestingly the 4 patients with a positive Lachman and pivot shift test, did not clinically feel unstable and did not require revision surgery. This finding is consistent with other similar studies [5][6][7][8][9][10][11][12] and is likely explained by the lower functional demands placed on the knee in this older cohort.
Another important finding in this study is that both functional outcome scores and overall activity level increased post-operatively as reflected by the improvement in Lysholm and Tegner scores, respectively. Lysholm, IKDC, and Tegner scores were all comparable to results seen in younger control groups and previous studies on ACLR for patients over 40 years of age which suggests that age alone should not be a cutoff for ACLR. A normative study by Anderson et al found that in a population 51-55 years of age, the mean IKDC score was 77 which suggests that post-operative ACLR patients have a higher score than their peers as our score was 83.2 [18]. In a validation study of the Lysholm score and Tegner activity scale by Briggs et al, the minimum detectable difference was found to be 8.9 for Lysholm and 1 for Tegner [19]. The results from our review indicate that the difference between pre-operative and post-operative Lysholm score (Δ-27.5) represent an increase while the Tegner scores (Δ0.3) indicate that pre-injury and postoperative scores are statistically the same. A study by Wolfson et al suggests the only factor portending a negative outcome was found to be patellofemoral arthritis [20]. This finding suggests that while medial compartment or lateral compartment arthritis are often cited as reasons to avoid ACLR, this does not necessarily lead to worse outcomes.

Conclusion
The results of this systematic review support hamstring autograft as a viable graft option for ACLR in patients over 50 with excellent functional outcomes, high patient satisfaction, low failure rates and minimal donor site morbidity.