Anterior Cruciate Ligament Reconstruction Registry Research Articles

Posterior Tibial Slope Measured on Plain Radiograph Versus MRI and Its Association With Revision Anterior Cruciate Ligament Reconstruction: A Matched Case-Control Study.

Posterior tibial slope (PTS) has been identified as a possible modifiable risk factor for anterior cruciate ligament (ACL) injury and ACL reconstruction (ACLR) failure. However, the findings in the literature are inconsistent. This may be explained by several different reasons, including different measurement methods, differing definitions of ACLR failure, and possible inclusion of suboptimal films. To compare PTS values obtained using plain radiographs (XR-PTS) in a young (≤21 years of age), skeletally mature patient population with those obtained using magnetic resonance imaging (MRI), as well as to quantify the number of suboptimal lateral knee radiographs obtained across an integrated health care system and determine the potential effect of including these radiographs on summary statistics of XR-PTS. Case-control study; Level of evidence, 3. Skeletally mature adolescent and young adult patients ≤21 years of age were identified from the ACLR registry of Kaiser Permanente. The cases of concern were patients requiring revision ACLR. The controls were patients who had an ACLR and did not require a revision procedure. The XR-PTS measurements were made on plain radiographs by a single blinded reviewer. These results were compared with measurements obtained using MRI. The quality of each plain radiograph was evaluated by measuring posterior/distal femoral condylar overlap and length of tibial diaphysis captured on the radiograph. Summary statistics with and without inclusion of measurements made on suboptimal radiographs were calculated. Of the initial 634 patients with ACLR (317 case-control pairs), 561 (88.5%) had radiographs available and were included for the analysis comparing radiograph to MRI slope measurements. For the evaluation of slope between case and control pairs with radiograph information available, there were 257 case-control pairs; there were 124 pairs when those with suboptimal radiographs were excluded. There was no difference in MRI-measured lateral tibial posterior slope or medial tibial posterior slope for the 257 case-control pairs with XR-PTS information and for the 124 pairs with optimal radiographs. XR-PTS in the revision cohort was significantly steeper than in the control group when suboptimal radiographs were included in the analysis. There was no difference when patients with suboptimal radiographs were excluded. PTS measurements made on plain radiographs were larger than those made on MRI. There was a poor correlation between measurements made using these 2 modalities (r = 0.22 for radiograph and medial PTS). This study did not find a significantly steeper XR-PTS in patients who had to undergo revision ACLR when suboptimal radiographs were not included in the analysis. The present study's results confirmed the findings from a previous study of the same patient population that used MRI. However, there was poor correlation between PTS measurements made using plain radiograph and MRI.

Patient and Operative Risk Factors for Osteoarthritis After Primary Anterior Cruciate Ligament Reconstruction: A Cohort Study of 41,976 Patients

Background: The reported incidence of posttraumatic knee osteoarthritis (PTOA) after primary anterior cruciate ligament reconstruction (ACLR) varies considerably. Further, there are gaps in identifying which patients are at risk for PTOA after ACLR and whether there are modifiable factors. Purpose: To (1) determine the incidence of PTOA in a primary ACLR cohort and (2) identify patient and perioperative factors associated with the development of PTOA after primary ACLR. Study Design: Cohort study; Level of evidence, 3. Methods: Data from the Kaiser Permanente ACLR Registry were used to conduct a cohort study. Patients who had undergone primary ACLR without a previous diagnosis of osteoarthritis were identified (2009-2020). The crude incidence of PTOA was calculated using the Aalen-Johansen estimator with a multistate model. The association of patient and operative factors with the development of PTOA after primary ACLR was modeled as a time to event using multistate Cox proportional hazards regression. Models stratified by age (<22 and ≥22 years) were also conducted because of the effect modification of age. Results: The study sample included 41,976 cases of primary ACLR. The incidence of PTOA was 1.7%, 5.1%, and 13.6% at 2, 5, and 10 year follow-ups, respectively. Risk factors for PTOA that were consistently identified in the overall cohort and age-stratified groups included a body mass index ≥30 versus <30 and an allograft or quadriceps tendon autograft versus a hamstring tendon autograft. Patients presenting with knee pain after ACLR were further identified when considering postoperative factors. Other risk factors for PTOA in the overall cohort included age ≥22 versus <22 years, bone–patellar tendon–bone autograft versus hamstring tendon autograft, hypertension, cartilage injury, meniscal injury, revision after primary ACLR with concomitant meniscal/cartilage surgery, multiligament injury, other activity at the time of injury compared with sport, and tibial tunnel drilling technique rather than the anteromedial portal. Conclusion: Knee pain after ACLR may be an early sign of PTOA. Surgeons should consider the adverse associations of a higher body mass index and an allograft or quadriceps tendon autograft with the development of PTOA, as these were factors identified with a higher risk, regardless of a patient’s age at the time of primary ACLR.

Risk of Revision and Reoperation After Quadriceps Tendon Autograft ACL Reconstruction Compared With Patellar Tendon and Hamstring Autografts in a US Cohort of 21,973 Patients

Background: The use of quadriceps tendon (QT) autografts has increased in the past 10 years. However, there remains a dearth of large studies examining the effects of graft selection on anterior cruciate ligament reconstruction (ACLR) that includes QT grafts. Purpose: To evaluate the risk of subsequent surgical outcomes, including revision and reoperation, for a large cohort of patients with primary ACLR according to autograft selection. Study Design: Cohort study; Level of evidence, 2. Methods: Data from a US health care system ACLR registry were used to conduct a cohort study. Primary isolated autograft ACLRs were identified (2012-2021). The exposure of interest was autograft type: QT, bone–patellar tendon–bone (BPTB), and hamstring tendon (HT). Multivariable Cox regression models were used to evaluate the risk of aseptic revision (defined as a subsequent surgery where removal and replacement of the original graft for noninfectious reasons was required) and risk of aseptic reoperation (defined as any subsequent surgery for noninfectious reasons where the graft was left intact) according to autograft selection. Results: The study sample comprised 21,973 ACLRs performed by 290 surgeons at 53 hospitals. QT, BPTB, and HT autografts were used in 1103 (5.0%), 9519 (43.3%), and 11,351 (51.7%) ACLRs, respectively. In adjusted models, no significant differences were observed in revision risk (hazard ratio [HR], 1.06; 95% CI, 0.60-1.89; P = .837) or reoperation risk (HR, 1.00; 95% CI, 0.70-1.43; P = .993) within 4 years of follow-up when comparing QT ACLR with BPTB ACLR. Additionally, no differences in 4-year revision (HR, 0.62; 95% CI, 0.34-1.12; P = .111) or reoperation (HR, 1.24; 95% CI, 0.85-1.80; P = .262) risks were observed when comparing QT ACLR with HT ACLR. HT ACLRs were noted to have a higher risk of revision (HR, 1.52; 95% CI, 1.25-1.84; P < .001) compared with BPTB ACLRs but a lower risk of reoperation (HR, 0.86; 95% CI, 0.75-0.98; P = .024). Conclusion: In this large multicenter study using data from an ACLR registry, the authors found no difference in the risk of revision or reoperation when QT was compared with BPTB or HT autograft with the numbers available, but they did find a 1.5 times higher risk of revision when HT autograft was compared with BPTB autograft. Surgeons may use this information when choosing the appropriate graft for ACLR in their patients.

No difference in revision risk between autologous hamstring graft less than 8mm versus hybrid graft 8mm or larger in anterior cruciate ligament reconstruction.

Hamstring autograft (HA) is commonly used for primary anterior cruciate ligament reconstruction (ACLR). However, if the harvested HA is inadequate in diameter, it is often augmented with an allograft tendon, forming a hybrid graft (HY). This study sought to evaluate aseptic revision risk following HA versus HY ACLR. A retrospective cohort study was performed using data obtained from our healthcare system's ACLR registry. Patients ≤ 25years of age who underwent primary isolated ACLR were identified (2005-2020). Graft type and diameter size was the primary exposure of interest: < 8mm HA and ≥ 8mm HY. A secondary analysis was performed to examine 7mm HA and 7.5mm HA vs ≥ 8mm HY. Propensity score-weighted Cox proportional hazard regression was used to evaluate the risk of aseptic revision. The study sample included 1,945 ACLR: 548 ≥ 8mm HY, 651 7mm HA, and 672 7.5mm HA. The crude cumulative aseptic revision probability at 8-years for ≥ 8mm HY was 9.1%, 11.1% for 7mm HA, and 11.2% for 7.5mm HA. In adjusted analysis, no difference in revision risk was observed for < 8mm HA (hazard ratio [HR] 1.15, 95% confidence interval [CI] 0.72-1.82), 7mm HA (HR 1.23, 95% CI 0.71-2.11), or 7.5mm HA (HR 1.16, 95% CI 0.74-1.82) compared to ≥ 8mm HY. In a US-based cohort of ACLR patients aged ≤ 25years, we failed to observe any differences in aseptic revision risk for HA < 8mm compared to HY ≥ 8mm. Augmentation of a HA as small as 7mm is not necessary to prevent a revision surgery. Level III.

Paper 13: Risk of Revision and Re-operation after ACL Reconstruction. Comparison of Quadriceps Tendon, BPTB, and Hamstring Autografts in a US-based Cohort Study of 19,960 Patients

Objectives: The purpose of this study was to evaluate risk for subsequent surgical outcomes, including revision and re-operation, for a cohort of primary anterior cruciate ligament reconstruction (ACLR) patients according to autograft selection. Methods: Data from a US healthcare system’s ACLR registry was used to conduct a cohort study. Primary isolated autograft ACLR patients were identified (2012-2020); those with prior procedures in the same knee were excluded. The exposure of interest autograft type: Quadriceps tendon (QT), bone-patellar tendon-bone (BPTB), and hamstring tendons. Multivariable Cox proportional hazard regression models were used to evaluate the risk for revision and risk for re-operation within 3-years follow-up according to autograft selection. Age, body mass index, gender, race/ethnicity, American Society of Anesthesiologist’s classification, activity at the time of injury, prior contralateral ACLR, lateral meniscus injury, medial meniscus injury, femoral fixation method, femoral tunnel drilling technique, average annual surgeon volume, operative time, and operative year were considered as covariates in regression analysis; models also included a cluster term for operating surgeon to account for correlation of ACLR performed by the same surgeon. Hazard ratios (HR) and 95% confidence intervals are reported. Two-sided tests were calculated with p&lt;0.05 the threshold for statistical significance. Results: The study sample comprised 19,960 ACLR performed by 280 surgeons at 51 hospitals. QT, BPTB, and hamstring autograft were used in 733 (3.7%), 8578 (43.0%), and 10,649 (53.3%) ACLR, respectively. The Figure presents the cumulative incidence of revision (left panel) and reoperation (right panel) during follow-up by graft type; number of patients still at risk for each year of follow-up is presented along the x-axis. In adjusted models, no significant differences were observed in revision risk (HR=1.52, 95% CI=0.83-2.80, p=0.177) or re-operation risk (HR=1.00, 95% CI=0.63-1.59, p=0.742) within 3-years follow-up when comparing QT ACLR to BPTB ACLR. Additionally, no differences in 3-year revision (HR=0.89, 95% CI=0.46-1.74, p=0.742) or re-operation (HR=1.21, 95% CI=0.74-1.99, p=0.442) risks were observed when comparing QT ACLR to hamstring ACLR. BPTB were noted to have a significantly lower risk of revision (HR=0.68, 95% CI=0.52-0.89, p=0.006) compared to hamstring tendons but no difference in risk of re-operation (HR=1.24, 95% CI=0.95-1.65, p=0.113). Conclusions: The results of this large multi-center study using data from an ACLR registry found no difference in the risk of revision or re-operation when quadriceps tendon was compared to BPTB or hamstring autograft with the numbers available but did find a 1.5 times higher risk of revision when hamstring tendon autograft was compared with BPTB autograft. Surgeons may use this information when choosing the appropriate graft for ACLR in their patients.

International cooperation needed to improve national anterior cruciate ligament registries.

The aim of this study is to illustrate an overview of the registries currently operative in many countries to support the introduction of new prospective registries in other countries. The authors carried out a systematic web research in July 2021 to identify national ACL registries' annual reports and scientific literature on national ACL registries. The latest annual public registry reports were collected and analyzed in this study. There are currently established national ACL registries in Norway, Denmark, Sweden, Luxembourg, New Zealand, the United Kingdom (UK), and the Kaiser Permanente National Anterior Cruciate Ligament Reconstruction Registry in the United States (US). Some differences can be found among the various registries due to the local healthcare system structure, data management rules, and general national laws. It is possible to develop accessible, cost-effective and entirely web-based ACL registries-as demonstrated by the Danish and Swedish registries-respecting the national legislation of different countries. This study supports the introduction of new ACL prospective registries in other countries to obtain valuable information for implementing daily clinical practice. IV.

Poster 252: Revision Risk of Hamstring Versus Hybrid Graft in Anterior Cruciate Ligament Reconstruction

Objectives:Hamstring autograft (HA) is a commonly used graft for anterior cruciate ligament reconstruction (ACLR). Hamstring tendon harvest can occasionally result in a small diameter graft, leaving the surgeon with several options. One option is to augment the hamstring graft with allograft tendon to increase the combined graft diameter forming a hybrid graft (HG). Inconsistent results of HG reconstructions have been reported, with some studies reporting worse outcomes for HG while others showing no difference between the two types of grafts. However, these studies have small sample sizes or are of an older patient population. The purpose of our study was to compare the revision rates of HA versus HG grafts in a young patient population.Methods:We conducted a retrospective cohort study of prospectively collected data from our integrated healthcare system’s ACLR Registry. Patients <25 years of age with a primary, isolated ACLR performed between 2005-2020 were identified; those with prior surgery in the index knee, double bundle, and infections (septic revisions) were excluded. The exposure of interest was graft type and diameter size, including <8mm HA and >8mm HG. Hybrid graft was defined as a hamstring tendon augmented with an allograft tendon to increase the graft diameter. Grafts with unknown diameter sizes and other graft types were excluded. A secondary analysis examined 7mm and 7.5mm HA vs >8mm HG. Propensity score-weighted Cox proportional hazard regression was used to evaluate the risk of aseptic revision during follow-up. Propensity score weights were calculated prior to evaluation of the outcome using multivariable logistic regression analysis and included age, sex, body mass index, race/ethnicity, femoral fixation, tibial fixation, femoral tunnel method, and activity at injury. Hazard ratios (HR) and 95% confidence intervals (CI) are presented. A P<0.05 was considered statistically significant.Results:The final cohort comprised 1,945 ACLR (548 were >8mm HG and 1397 were <8mm HA, including 651 with 7mm diameters and 672 with 7.5mm). At 8-years follow-up, the crude cumulative aseptic revision probability for >8mm HG was 9.1%, while <8mm HA was 10.9% (Figure 1); corresponding cumulative probabilities for 7mm and 7.5mm HA were 11.1% and 11.2% respectively. After adjustment with propensity score weighting, we failed to observe a difference in aseptic revision risk for <8mm HA compared with >8mm HG (HR=1.15, 95% CI = 0.72-1.82, p=0.56) (Table 1). Similarly, no difference was observed for 7mm HA (HR= 1.23, 95% CI=0.71-2.11, p=0.46) and 7.5mm HA (HR=1.16, 95% CI =0.74-1.82, p=0.52) compared to HG.Conclusions:In our cohort study of 1,945 patients, we failed to detect a statistical difference in the risk of aseptic revision between a HA < 8mm and a HG > 8mm. The clinical significance is that augmentation of HA with an allograft does not appear to decrease the risk of aseptic revision and may not be necessary. Future studies should be conducted to confirm these findings.Figure 1.Cumulative Incidence of Aseptic Revision by Graft Type/Diameter Size.Table 1.Crude Cumulative Revision Probability And Adjusted Risk After Aclr By Graft Type/Diameter Size.

Poster 251: Autograft Associated with Lower Risk of Repeat Revision Anterior Cruciate Ligament Reconstruction than Allograft: Results from a Large Integrated Healthcare System

Objectives:With the rising utilization of primary anterior cruciate ligament reconstruction (ACLR), the burden of revision ACLR (rACLR) has also increased. Graft choice for rACLR is complicated by patient factors and the remaining available graft options. This study examines the relationship between graft type at the time of rACLR and the risk of repeat rACLR (rrACLR).Methods:We conducted a cohort study from a US integrated healthcare system’s ACLR registry. The study population included patients with a primary isolated ACLR, between 2005-2020, who then went on to have an aseptic rACLR. Graft type used at revision surgery, classified as autograft versus allograft, was the exposure of interest. Multivariable Cox proportional hazard regression was used to evaluate the risk of aseptic rrACLR with ipsilateral and contralateral reoperation as secondary outcomes. Models included factors at the time of the revision procedure (age, gender, body mass index, smoking status, staged revision, femoral fixation, tibial fixation, femoral tunnel method, lateral meniscus injury, medial meniscus injury, and cartilage injury) and a factor from the primary ACLR (activity at injury) as covariates.Results:1747 rACLR procedures were included. The crude cumulative aseptic rrACLR incidence at 8-years follow-up was 13.9% for allograft and 6.0% for autografts (Figure 1). Cumulative ipsilateral reoperation incidence at 8-years follow-up was 18.3% for allograft and 18.9% for autograft; contralateral reoperation cumulative incidence was 4.3% for allograft and 6.8% for autograft. With adjustment for covariates, a lower aseptic rrACLR risk was observed for autografts compared with allografts (HR=0.30, 95% CI=0.18-0.50, p <0.0001). No differences were observed for ipsilateral reoperation (HR=1.05, 95% CI=0.73-1.51, p=0.78) nor for contralateral reoperation (HR=1.33, 0.60-2.97, p=0.48) for autografts compared with allografts.Conclusions:The use of autograft at rACLR was associated with a 70% reduced risk of rrACLR compared to allograft in this large integrated health care system registry. When accounting for all reoperations after rACLR, we found no significant difference in risk between autograft and allograft. In order to minimize the risk of rrACLR, surgeons should consider using autograft for rACLR when possible.Figure 1.Cumulative Incidence of Asceptic Re-revision by Graft Type.

Association Between Anteromedial Portal Versus Tibial Tunnel Drilling and Meniscal Reoperation Risk Following Anterior Cruciate Ligament Reconstruction: A Cohort Study

Background: Anterior cruciate ligament reconstruction (ACLR) provides functional stability to an injured knee. While multiple techniques can be used to drill the femoral tunnel during ACLR, a single technique has yet to be proven as clinically superior. One marker of postoperative functional stability is subsequent meniscal tears; a lower risk of subsequent meniscal surgery could be expected with improved knee stability. Purpose: To determine if there is a meniscal protective effect when using an anteromedial portal (AMP) femoral tunnel drilling technique versus transtibial (TT) drilling. Study Design: Cohort study; Level of evidence, 2. Methods: Data from Kaiser Permanente’s ACLR registry were used to identify patients who had a primary isolated ACLR between 2009 and 2018; those with previous surgery in the index knee and meniscal pathology at the time of ACLR were excluded. The exposure of interest was TT (n = 2711) versus AMP (n = 5172) drilling. Multivariable Cox proportional hazard regression was used to evaluate the risk of a subsequent ipsilateral meniscal reoperation with adjustment for age, sex, femoral fixation, and graft choice. We observed a shift in surgeon practice from the TT to AMP over the study time frame; therefore, the relationship between technique and surgeon experience on meniscal reoperation was evaluated using an interaction term in the model. Results: At the 9-year follow-up, the crude cumulative meniscal reoperation probability for AMP procedures was 7.76%, while for TT it was 5.88%. After adjustment for covariates, we observed a higher risk for meniscal reoperation with AMP compared with TT (hazard ratio [HR], 1.53; 95% CI, 1.05-2.23). When stratifying by surgeon experience, this adverse association was observed for patients who had their procedure performed by surgeons with less AMP experience (no previous AMP ACLR: HR, 1.26; 95% CI, 0.84-1.91) while a protective association was observed for patients who had their procedure with more experienced surgeons (40 previous AMP ACLRs: HR, 0.34; 95% CI, 0.13-0.92). Conclusion: Drilling the femoral tunnel via the AMP was associated with a higher risk of subsequent meniscal surgery compared with TT drilling. However, when AMP drilling was used by surgeons experienced with the technique, a meniscal protective effect was observed.

Acute and subacute anterior cruciate ligament reconstructions are associated with a higher risk of revision and reoperation.

(1) Report concomitant cartilage and meniscal injury at the time of anterior cruciate ligament reconstruction (ACLR), (2) evaluate the risk of aseptic revision ACLR during follow-up, and (3) evaluate the risk of aseptic ipsilateral reoperation during follow-up. Using a United States integrated healthcare system's ACLR registry, patients who underwent primary isolated ACLR were identified (2010-2018). Multivariable Cox proportional-hazards regression was used to evaluate the risk of aseptic revision, with a secondary outcome evaluating ipsilateral aseptic reoperation. Outcomes were evaluated by time from injury to ACLR: acute (< 3weeks), subacute (3weeks-3months), delayed (3-9months), and chronic (≥ 9months). The final sample included 270 acute (< 3weeks), 5971 subacute (3weeks-3months), 5959 delayed (3-9months), and 3595 chronic (≥ 9months) ACLR. Medial meniscus [55.4% (1990/3595 chronic) vs 38.9% (105/270 acute)] and chondral injuries [40.0% (1437/3595 chronic) vs 24.8% (67/270 acute)] at the time of ACLR were more common in the chronic versus acute groups. The crude 6-year revision rate was 12.9% for acute ACLR, 7.0% for subacute, 5.1% for delayed, and 4.4% for chronic ACLR; reoperation rates a 6-year follow-up was 15.0% for acute ACLR, 9.6% for subacute, 6.4% for delayed, and 8.1% for chronic ACLR. After adjustment for covariates, acute and subacute ACLR had higher risks for aseptic revision (acute HR 1.70, 95% CI 1.07-2.72, p = 0.026; subacute HR 1.25, 95% CI 1.01-1.55, p = 0.040) and aseptic reoperation (acute HR 2.04, 95% CI 1.43-2.91, p < 0.001; subacute HR 1.31, 95% CI 1.11-1.54, p = 0.002) when compared to chronic ACLR. In this cohort study, while more meniscal and chondral injuries were reported for ACLR performed ≥ 9months after the date of injury, a lower risk of revision and reoperation was observed following chronic ACLR relative to patients undergoing surgery in acute or subacute fashions.

Optimizing anterior cruciate ligament reconstruction: Individualizing the decision-making process using data from the Kaiser Permanente ACLR Registry: 2018 OREF award paper.

Despite years of study, controversy remains regarding the optimal graft for anterior cruciate ligament reconstruction (ACLR), suggesting that a single graft type is not ideal for all patients. A large community based ACLR Registry that collects prospective data is a powerful tool that captures information and can be analyzed to optimize surgery for individual patients. The studies highlighted in this paper were designed to optimize and individualize ACLR surgery and have led to changes in surgeon behavior and improvements in patient outcomes. Kaiser Permanente (KP) is an integrated health care system with 10.6 million members and more than 50 hospitals. Every KP member who undergoes an ACLR is entered into the Registry, and prospectively monitored. The Registry uses a variety of feedback mechanisms to disseminate Registry findings to the ACLRR surgeons and appropriately influence clinical practices and enhance quality of care. Allografts were found to have a 3.0 times higher risk of revision than bone-patellar tendon-bone (BPTB) autografts. Allograft irradiation >1.8 Mrad, chemical graft processing, younger patients, BPTB allograft, and male patients were all associated with a higher risk of revision surgery. By providing feedback to surgeons, overall allograft use has decreased by 27% and allograft use in high-risk patients ≤21 years of age decreased 68%. We have identified factors that influence the outcomes of ACLR. Statement of Clinical Significance: We found that information derived from an ACLR Registry and shared with the participating surgeons directly decreased the use of specific procedures and implants associated with poor outcomes.

Aseptic Revision and Reoperation Risks After Meniscectomy at the Time of Anterior Cruciate Ligament Reconstruction

Background: An intact meniscus is considered a secondary stabilizer of the knee after anterior cruciate ligament reconstruction (ACLR). While loss of the meniscus can increase forces on the anterior cruciate ligament graft after reconstruction, it is unclear whether this increased loading affects the success of the graft after ACLR. Purpose: To identify the risk of subsequent knee surgery when meniscectomy, either partial or total, is performed at the time of index ACLR. Study Design: Cohort study; Level of evidence, 3. Methods: We conducted a matched cohort study using data from the Kaiser Permanente Anterior Cruciate Ligament Reconstruction Registry. Patients were identified who had a primary ACLR performed between January 1, 2005 and December 31, 2016, with up to 12 years of follow-up. The study sample comprised patients with ACLR who had a lateral meniscectomy (n = 2581), medial meniscectomy (n = 1802), or lateral and medial meniscectomies (n = 666). For each meniscectomy subgroup, patients with ACLR alone were matched to patients with a meniscectomy on a number of patient and procedure characteristics. After the application of matching, Cox proportional hazards regression was used to evaluate the risk of aseptic revision, while competing risks regression was used to evaluate the risk of cause-specific ipsilateral reoperation between meniscectomy and ACLR alone. Analysis was performed for each meniscectomy subgroup. Results: After the application of matching, we failed to observe a difference in aseptic revision risk for patients with ACLR and a meniscectomy—lateral (hazard ratio [HR], 0.80; 95% CI, 0.63-1.02), medial (HR, 0.95; 95% CI, 0.70-1.29), or both (HR, 1.25; 95% CI, 0.77-2.04)—as compared with ACLR alone. When compared with patients who had ACLR alone, patients with a lateral meniscectomy had a higher risk for subsequent lateral meniscectomy (HR, 1.89; 95% CI, 1.18-3.02; P = .008), and those with a medial meniscectomy had a lower risk for manipulation under anesthesia (HR, 0.13; 95% CI, 0.02-0.92; P = .041). Conclusion: No difference in aseptic revision risk was observed for patients undergoing primary ACLR between groups with and without meniscectomy at the time of index surgery. Partial lateral meniscectomy at the time of index ACLR did associate with a higher risk of subsequent lateral meniscectomy.

Revision Risk of Soft Tissue Allograft Versus Hybrid Graft After Anterior Cruciate Ligament Reconstruction

Background: When a harvested hamstring autograft is deemed by the surgeon to be of inadequate diameter, the options include using the small graft, using another autograft from a different site, augmenting with an allograft (hybrid graft), using a different configuration of the graft (eg, 5- or 6-stranded), or abandoning the autograft and using allograft alone. A small graft diameter is associated with a higher revision risk, and using another autograft site includes added harvest-site morbidity; therefore, use of a hybrid graft or an allograft alone may be appealing alternative options. Revision risk for hybrid graft compared with soft tissue allograft is not known. Purpose: To evaluate the risk for aseptic revision surgery after primary anterior cruciate ligament reconstruction (ACLR) using a soft tissue allograft compared with ACLR using a hybrid graft in patients 25 years and younger. Study Design: Cohort study; Level of evidence, 3. Methods: Data from a health care system’s ACLR registry were used to identify primary isolated unilateral ACLRs between 2009 and 2016 using either a hybrid graft (hamstring autograft with soft tissue allograft) or a soft tissue allograft alone. Multivariable Cox proportional hazards regression was used to evaluate risk for aseptic revision after ACLR according to graft used after adjustment for age, allograft processing, tunnel drilling technique, and region where the primary ACLR was performed. Results: The cohort included 2080 ACLR procedures; a hybrid graft was used for 479 (23.0%) ACLRs. Median follow-up time was 3.4 years (interquartile range, 1.8-5.1 years). The crude 2-year aseptic revision probability was 5.4% (95% CI, 4.3%-6.7%) for soft tissue allograft ACLR and 3.8% (95% CI, 2.3%-6.4%) for hybrid graft ACLR. After adjustment for covariates, soft tissue allograft ACLR had a higher risk of aseptic revision during follow-up compared with hybrid graft ACLR (hazard ratio, 2.00; 95% CI, 1.21-3.31; P = .007). Conclusion: Soft tissue allografts had a 2-fold higher risk of aseptic revision compared with hybrid graft after ACLR. Future studies evaluating the indications for using hybrid grafts and the optimal hybrid graft diameter is needed.

Revision Risk Of Soft Tissue Allograft Versus Hybrid Graft Following Anterior Cruciate Ligament Reconstruction

Objectives: Prior studies have found smaller hamstring autograft diameter to be associated with a higher revision risk following anterior cruciate ligament reconstruction (ACLR). Therefore, when a harvested hamstring autograft is deemed by the surgeon to be of inadequate diameter, the options include: using the small graft, using another autograft from a different site, augmenting with an allograft (hybrid graft), or abandoning the autograft and using allograft alone. Using another autograft site includes added harvest-site morbidity, therefore utilization of an allograft to augment the autograft (hybrid) or allograft alone may be an appealing alternative option. Revision risk for hybrid graft compared to soft tissue allograft in is not known. The purpose of our study was to determine the risk for aseptic revision following soft tissue allograft ACLR compared to hybrid graft ACLR in patients 25 years and younger. Methods: Data from a healthcare system’s ACLR registry was used to conduct a cohort study. Primary isolated unilateral ACLR from 2009-2016 using either a hybrid graft (hamstring autograft + soft tissue allograft) or soft tissue allograft alone were identified. Time-to-aseptic revision surgery following primary ACLR was the primary endpoint. Multivariable Cox proportional hazard regression was used to evaluate risk for aseptic revision according to graft utilization after adjustment for age, allograft processing, tunnel drilling technique, and region where the primary ACLR was performed. Analysis censored patients at the time lost to follow-up (healthcare plan termination or death) or the end of study follow-up. A sandwich covariance matrix estimator was used to account for clustering of ACLR at the surgeon level. Results: The cohort included 2080 ACLR performed by 161 surgeons at 42 healthcare centers. Soft tissue allograft was used for 1601 (77.0%) ACLR and hybrid graft for 478 (23.0%). For the soft tissue allograft ACLR group, mean age was 19.2 (standard deviation [SD]=3.5) years, 79.1% of allografts were irradiated or chemically processed, and 50.4% of femoral tunnels were through the trans-tibial technique. For the hybrid graft ACLR group, mean age was 18.4 (SD=3.3) years, 81.5% were irradiated or chemically processed, and 72.3% of femoral tunnels were through the trans-tibial technique. Median follow-up time was 3.4 years (interquartile range=1.8-5.1 years). The crude 2-year aseptic revision probability was 5.4% (95% confidence interval [CI]=4.3-6.7) for soft tissue allograft ACLR and 3.8% (95% CI=2.3-6.4) for hybrid ACLR. After adjustment for covariates, soft tissue allograft ACLR had a higher risk of aseptic revision during follow-up compared to hybrid graft ACLR (hazard ratio=2.00, 95% CI=1.21-3.31, p=0.007). Conclusion: Soft tissue allograft had twice the risk of aseptic revision compared to hybrid graft following ACLR. Based on our findings, when faced with a hamstring autograft that is deemed to have an inadequate diameter, augmenting it with allograft tendon may be preferred over abandoning it for an allograft alone. Future study evaluating the indications and the optimal hybrid graft diameter is needed.

The Association Between Race/Ethnicity and Revision Following ACL Reconstruction in a Universally Insured Cohort.

There have been few large studies involving multiethnic cohorts of patients treated with anterior cruciate ligament reconstruction (ACLR), and therefore, little is known about the role that race/ethnicity may play in the differential risk of undergoing revision surgery following primary ACLR. The purpose of this study was to evaluate whether differences exist by race/ethnicity in the risk of undergoing the elective procedure of aseptic revision in a universally insured cohort of patients who had undergone ACLR. This was a retrospective cohort study conducted using our integrated health-care system's ACLR registry and including primary ACLRs from 2008 to 2015. Race/ethnicity was categorized into the following 4 groups: non-Hispanic white, black, Hispanic, and Asian. Multivariable Cox proportional-hazard models were used to evaluate the association between race/ethnicity and revision risk while adjusting for age, sex, highest educational attainment, annual household income, graft type, and geographic region in which the ACLR was performed. Of the 27,258 included patients,13,567 (49.8%) were white, 7,713 (28.3%) were Hispanic, 3,725 (13.7%) were Asian, and 2,253 (8.3%) were black. Asian patients (hazard ratio [HR] = 0.72; 95% confidence interval [CI] = 0.57 to 0.90) and Hispanic patients (HR = 0.83; 95% CI = 0.70 to 0.98) had a lower risk of undergoing revision surgery than did white patients. Within the first 3.5 years postoperatively, we did not observe a difference in revision risk when black patients were compared with white patients (HR = 0.86; 95% CI = 0.64 to 1.14); after 3.5 years postoperatively, black patients had a lower risk of undergoing revision (HR = 0.23; 95% CI = 0.08 to 0.63). In a large, universally insured ACLR cohort with equal access to care, we observed Asian, Hispanic, and black patients to have a similar or lower risk of undergoing elective revision compared with white patients. These findings emphasize the need for additional investigation into barriers to equal access to care. Because of the sensitivity and complexity of race/ethnicity with surgical outcomes, continued assessment into the reasons for the differences observed, as well as any differences in other clinical outcomes, is warranted. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Risk Factors for Opioid Use Following Anterior Cruciate Ligament Reconstruction (ACLR) in a Cohort of 21,202 ACLR

Objectives: The misuse of opioid medication has contributed to a significant national crisis affecting public health, as well as patient morbidity and medical costs. We sought to determine baseline opioid utilization in patients undergoing ACLR and examine demographic, patient characteristics, and medical factors associated with postoperative opioid utilization. Methods: Primary elective ACLR were identified using an integrated healthcare system’s ACLR registry (January 2005-January 2015). Patients with cancer or those who had other knee surgery in the preceding year were excluded. We studied the effect of preoperative and intraoperative risks factors on number of dispensed opioid medication prescriptions (Rx) in the early (0-90 days) and late (91-360 days) postoperative periods using logit regression. Risk factors studied included: number of opioid Rx in preceding year, age, gender, race, American Society of Anesthesiologists (ASA) classification, body mass index (BMI), activity at the time of injury, time from injury to ACLR, concomitant procedure or injury, medical comorbidities, and opioid-use comorbidities. Results: Of 21202 ACLR from 20813 patients, 25.5% used at least 1 opioid Rx in the one-year preoperative period. 17.7% and 2.7% used ≥2 opioid Rx in the early and late recovery periods, respectively. The risk factors associated with greater opioid Rx in both the early and late periods included: preoperative opioid use, age &gt;20 years, ASA classification of ≥3, other activity at the time of injury, repaired cartilage injury, chronic pulmonary disease, and substance abuse. Risk factors associated with opioid Rx use during the early period only included: other race, acute ACL injury, repaired meniscal injury, multi-ligament injury, and dementia/psychoses. Risk factors associated with greater opioid Rx during the late period included: female gender, BMI &gt;25 kg/m2, motor vehicle accident as the mechanism of injury, and hypertension. Conclusion: We identified several risk factors for postoperative opioid usage after ACLR. The strongest predictors of postoperative prescription opioid usage after ACLR included preoperative opioid use, increasing age, ASA classification of 3 or more, other activity at the time of injury, repaired meniscal injury, cartilage repair, chronic pulmonary disease, and substance abuse. Awareness of risk factors for postoperative opioid usage may encourage more targeted utilization of opioids in pain management. Surgeons may consider additional support or referral to a pain specialist for patients with these risk factors. [Figure: see text]

Femoral Tunnel Drilling Method: Risk of Reoperation and Revision After Anterior Cruciate Ligament Reconstruction

Background: The femoral tunnel in anterior cruciate ligament reconstruction (ACLR) can be created by the transtibial (TT) or tibial-independent (TI) methods. An anatomically located femoral tunnel can be more consistently achieved by TI methods, which include the anteromedial portal and lateral (outside-in, retrodrill) techniques. Nonanatomic graft placement in ACLR can result in postoperative instability and meniscal or chondral injury. An anatomically located graft is subjected to higher postoperative physiologic forces than one placed nonanatomically. Purpose: To examine isolated primary ACLR and determine the risk of aseptic revision and reoperation based on femoral tunnel drilling method. Study Design: Cohort study; Level of evidence, 2. Methods: The ACLR registry of an integrated US health care system was used to identify primary isolated unilateral ACLRs from 2009 to 2014. Multivariable Cox proportional hazard regression models were used to evaluate risk for aseptic revision for graft failure and aseptic reoperation for meniscal or chondral injury according to femoral tunnel drilling method: TI versus TT. Models included age, sex, body mass index (BMI), race, graft type, and femoral fixation type as covariates. Results: The cohort included 19,059 patients with primary ACLR. The mean age was 28.9 years (SD, 11.5), 6991 patients (36.8%) were younger than 22 years, 11,795 patients (61.9%) were male, 7648 patients (40.1%) had a BMI less than 25 kg/m2, 8913 patients (46.8%) were white, and 7357 patients (38.6%) received an allograft. Median follow-up was 2.30 years (interquartile range, 1.08-3.77). TI techniques were used for 12,342 (64.8%) of the ACLRs, and the TT method was used for 6717 (35.2%). Use of TI techniques increased from 33.6% of all ACLRs in 2009 to 83.4% in 2014. After adjustment for covariates, the TI group had a higher risk for aseptic revision than the TT group (hazard ratio [HR], 1.28; 95% CI, 1.04-1.56), and this risk was 1.41 times higher in patients younger than 22 years specifically. The 5-year cumulative reoperation probability was lower in the TI group (4.50%; 95% CI, 3.78%-5.36%) compared with the TT group (5.06%; 95% CI, 4.31-5.94%). After adjustment for the covariates, no difference in risk for aseptic reoperation was observed (HR, 1.08; 95% CI, 0.85-1.39). Conclusion: In the largest known study of its type examining femoral tunnel drilling method for primary ACLR, after adjustment for age, sex, BMI, race, graft type, and femoral fixation, TI techniques were found to carry higher risk of aseptic revision compared with the TT method, while no difference was observed in risk for aseptic reoperation.

Risk factors associated with ACL registry compliance: can we predict who will follow-up?

The purpose of this study was to determine patient factors that influence patient compliance to fill out anterior cruciate ligament reconstruction (ACLR) registry forms. Patients prospectively enrolled in the ACLR registry at a single institution were retrospectively reviewed. Patients who were followed up for at least 6months were included. Patients who did not fill out initial registry forms were excluded. Patients were asked to fill out forms preoperatively and at 6, 12 and 24months postoperatively. The impacts of age, race, employment status, medical insurance, smoking status, driving distance to the hospital and importance to return to the same level of sporting activity were analyzed against patient compliance (yes/no) to complete registry forms at the respective follow-ups. Multivariate analysis was performed to analyze variables at 6 and 12months postoperatively. The numbers of patients who were followed up for more than 24months were too low to run a multivariate analysis, so only univariate analysis was performed on this cohort. A total of 221 patients filled out the initial preoperative forms at least 6months before data gathering was commenced and were included. At 6months postoperatively, none of the variables significantly influenced patient compliance. At 12months, younger age and longer driving distance to the hospital had a significant negative impact on compliance [OR per year: 0.92 (0.85-0.99), p = 0.0237; OR per mile: 1.01 (1, 1.01), p = 0.0297]. Patients who filled out registry forms at 6months were significantly more compliant at 12months postoperatively (p < 0.0001). At 24months, the influence of age remained significant (p = 0.0262) and, additionally, patients who initially noted that it was important for them to return to the same level of sports were significantly less compliant (p = 0.0367). Younger age and longer driving distance to the hospital were significantly associated with less compliance to fill out ACLR registry forms at 12months postoperatively. Patient perspectives on the importance to return to the same level of sports were inversely related to compliance at 24months postoperatively. This information can be utilized to improve compliance in future studies as we have potentially identified patients that can be viewed as "at-risk" for registry noncompliance.

The presence of concomitant intra-articular injuries and bone bruise does not affect pre-operative knee pain and symptoms in patients undergoing anterior cruciate ligament reconstruction.

Increased knee pain at the time of anterior cruciate ligament (ACL) reconstruction may predict increased pain post-operatively, a prolonged recovery and a more difficult rehabilitation. The main objective of our study was to identify preoperative factors, such as concomitant intra-articular injuries and bone bruises, that may be associated with increased knee pain and symptoms in patients undergoing ACL reconstruction. Patient data was queried from our institution's prospectively maintained ACL reconstruction registry. Two-hundred and seventy patients who underwent primary ACL reconstruction within 3 months of injury were included in the study. Predictors such as demographic characteristics (age, body mass index and gender) and injury characteristics (mechanism of injury, meniscal injury, chondral injury and bone bruise) were recorded. The association between the pre-operative knee injury and Osteoarthritis Outcome Score (KOOS) pain and symptom subscales and the Short Form-36 (SF-36) bodily pain subscale, and the predictors were assessed using logistic regression for categorical variables and linear regression for continuous variables. The mean age of our patient group was 25.4years with 211 out of 270 (78%) being males. Bone bruise was present in 243 patients (90%), meniscal injury in 165 (61%) patients and chondral injury in 40 (15%) patients. The presence of bone bruise, meniscal injury or chondral injury was not significantly associated with worse preoperative KOOS pain and symptom and SF-36 bodily pain scores. Other factors that were not associated were demographic characteristics (age, BMI and gender) and mechanism of injury. The presence of bone bruise and concomitant intra-articular injuries does not affect pre-operative knee pain and symptoms in patients undergoing ACL reconstruction within 3 months of injury. This knowledge would aid the surgeon in pre-operative counselling, and prognostication of post-operative pain and rehabilitation after ACL reconstruction.

Epidemiology of patients with anterior cruciate ligament injuries undergoing reconstruction surgery in a multi-ethnic Asian population

ABSTRACT We conducted an epidemiological study to identify the demographics and pre-operative characteristics of patients undergoing primary anterior cruciate ligament (ACL) reconstruction in a multi-ethnic Asian population. A retrospective study was performed on 696 patients who registered in our ACL reconstruction registry from January 2013 to August 2016. Important inter-ethnic differences were found. Indian patients were significantly older compared to Malay and Chinese patients. Malay and Indian patients were more likely to be male, overweight, and obese compared to Chinese patients. Soccer was the predominant sport involved, although ethnic predominance in specific sports exists. Novel findings from this study include increased prevalence of concomitant chondral injuries in the Chinese population compared to Malays and Indians, and significantly higher rates of concomitant intra-articular injuries in soccer and basketball compared to netball. Identification of these high-risk subgroups would serve useful in guiding the formulation of prevention strategies within our multi-ethnic community.