Bilateral Anterior Cruciate Ligament Reconstruction Research Articles

Functional outcomes in single stage bilateral ACL reconstruction with a maximum follow up of 10 years

BackgroundBilateral ACL injuries are a rarity and there is no particular consensus on whether this rare problem has to be tackled in stages or in a single stage. There are a few studies and case reports in the literature about the outcomes in single staged bilateral Anterior cruciate ligament reconstruction (ACLR). This study is focused on functional outcomes after a single staged bilateral ACLR, as well as impact of simultaneity of the injury, meniscal tears, notch stenosis and hyperlaxity. Materials and methodsA retrospective study was conducted from 2013 to 2021. Patients with bilateral ACL injury either simultaneous or non simultaneous, with or without meniscal tears were included in this study. Pre operative diagnosis was made both clinically and by MR imaging. All patients underwent a single staged bilateral ACL reconstruction. Pre operative functional scores (IKDC and Lysholm) were taken at admission and patients were examined at regular follow ups. Final functional scores were collected in a phone interview. Results33 patients underwent bilateral ACLR in a single stage during the study period but one patient had revision ACLR in one knee and so was excluded. Of the 32 patients, 25 (78%) had non simultaneous injury and 7 (22%) had a simultaneous injury, meniscus tear was noted in 27 (84.4%), notch stenosis in 19 (59.3%) and hyperlaxity in 12 (37.5%). IKDC and Lysholm scores have improved postoperatively. No statistically significant difference was found with or without simultaneous injury or meniscus tears. ConclusionSingle stage bilateral ACL reconstruction is a safe, reproducible approach to bilateral ACL injuries whether they were simultaneous or non simultaneous or with or without meniscal tears.

Patients with Bilateral ACL Reconstruction (ACLR) have 3x the Rate of Posterior Tibial Slope Greater than 12-Degrees Compared to Unilateral ACLR: MRI and Radiographic Evaluation

Objectives: Increased posterior tibial slope (PTS) is a risk factor for primary anterior cruciate ligament (ACL) tear and graft failure, but PTS has not been well-defined in those who have experienced bilateral ACL injuries. We aimed to compare PTS angles, as well as the rate of elevated PTS (>12° on lateral radiograph; >7° on MRI), between patients who underwent bilateral ACL reconstruction (ACLR) vs unilateral ACLR. A secondary purpose was to examine whether these associations remained consistent on both plain radiographs and MRIs. Methods: We retrospectively identified patients who underwent primary ACLR at our institution from the years 2012 to 2020. Patients with non-simultaneous bilateral ACLR (n=53) were propensity matched to those with unilateral ACLR (n=53) by age, sex, and BMI. Exclusion criteria were: rotated lateral radiographs, inadequate quality MRI, concomitant ligament injury or fracture. Unilateral ACLRs with less than 5-year follow-up were further excluded. Three blinded readers measured PTS on lateral radiographs, while medial (MPTS) and lateral PTS (LPTS) were measured on MRI. Bivariate regression was performed to determine correlation between radiograph and MRI measurements. Results: A final cohort of 106 patients was analyzed (mean age: 27.4 ± 10.5 years, 49.1% male, BMI: 25.5 ± 4.3). PTS in the bilateral ACLR cohort was significantly greater than the unilateral ACLR cohort on radiographs (11.26° vs 10.13°, p=0.044) and LPTS (7.32° vs 6.08°, p=0.012), but not MPTS (4.55° vs 4.17°, p=0.467). The percentage of bilateral patients with radiograph PTS >12° was 41.0%, compared to 13.2% in unilateral cohort (p=0.012). The bilateral cohort had a significantly greater rate of LPTS >7° compared to unilateral patients (53.8% vs 32.1%, p=0.016), but not MPTS (p=0.467). On MRI, LPTS (5.93° ± 3.20°) was significantly greater than MPTS (5.12° ± 2.78°, p<0.001). There was weak correlation between MPTS-radiograph ( R=0.24, p=0.02) and LPTS-radiograph was not significantly correlated ( R=0.03, p=0.810). Conclusions: Patients who underwent bilateral ACLR had significantly greater PTS on radiographs and LPTS on MRI compared to those with unilateral ACLR. The rate of PTS >12° was 3.1x greater among bilateral ACLR compared to unilateral ACLR. PTS measurements on radiographs demonstrated weak-to-negligible correlation with MRI measurements, suggesting future normative PTS values should be reported specific to the imaging modality.

Psychological Readiness to Return to Sport and Return to Sport Rates Are Similar in Patients After Either Bilateral or Unilateral Anterior Cruciate Ligament Reconstruction

To compare psychological readiness to return to sport (RTS), RTS rate, level of return, and time to return between patients who underwent bilateral anterior cruciate ligament reconstruction (ACLR) and those who underwent unilateral ACLR. The electronic medical record at a single academic medical center was queried for patients who underwent ACLR from January 2012 to May 2020. The inclusion criteria were skeletally mature patients who underwent either single or sequential bilateral ACLR and who had undergone either the primary ACLR or second contralateral ACLR at least 2 years earlier. Bilateral ACLRs were matched 1:3 to unilateral reconstructions based on age, sex, and body mass index. Psychological readiness to RTS was assessed using the validated ACL Return to Sport After Injury (ACL-RSI) scale. This, along with time to return and level of RTS, was compared between the 2 cohorts. In total, 170 patients were included, of whom 44 underwent bilateral ACLR and 132 underwent unilateral ACLR. At the time of the first surgical procedure, patients in the unilateral cohort were aged 28.8 ± 9.4 years and those in the bilateral cohort were aged 25.7 ± 9.8 years (P= .06). The average time difference between the first and second surgical procedures was 28.4 ± 22.3 months. There was no difference in psychological readiness to RTS (50.5 in bilateral cohort vs 48.1 in unilateral cohort, P= .66), RTS rate (78.0% in unilateral cohort vs 65.9% in bilateral cohort, P= .16), percentage of return to preinjury sport level (61.2% in unilateral cohort vs 69.0% in bilateral cohort, P= .21), or time to return (41.2± 29.3 weeks in unilateral cohort vs 35.2 ± 23.7 weeks in bilateral cohort, P= .31) between the 2 cohorts. Compared with patients who undergo unilateral ACLR, patients who undergo bilateral ACLR are equally as psychologically ready to RTS, showing equal rates of RTS, time to return, and level of return. Level III, retrospective cohort study.

Poster 340: Return to Sport and Psychological Readiness to Return to Sport in Individuals who Have Undergone Bilateral vs Unilateral ACL Surgeries

Objectives: Prior studies report lower return to preinjury level of sport in patients who undergo bilateral anterior cruciate ligament (ACL) reconstructions compared to unilateral reconstructions, with the most common cited reason being fear of reinjury. The purpose of our investigation was to compare subsequent return rates and psychological readiness to return to sport (RTS) in patients who underwent bilateral versus unilateral ACL reconstructions. Methods: A retrospective review of patients who underwent ACL reconstruction at a single academic institution between 2012-2021 with a minimum of 1-year follow-up was conducted. Patients were divided into bilateral and unilateral cohorts. Those who underwent bilateral ACL reconstruction were matched 1:3 to unilateral reconstruction based on age, sex, BMI, and primary sport. Primary outcomes included return to sport, level of RTS and psychological readiness to RTS, assessed by the validated ACL- Return to Sport after Injury (ACL-RSI) scale. Within the ACL-RSI questionnaire, fear and confidence to return to sport were specifically analyzed. Fear to RTS was measured on a scale of 0-100 with 0 equal to extremely fearful and 100 equal to no fear at all. Confidence to RTS was measured on a scale of 0-100 with 0 equal to not at all confidence and 100 equal to fully confident. Statistical analysis was performed in R studio, with chi-square used for categorical values and two-sided t-test for continuous. Results: One hundred eighty-one patients were included, forty-three bilateral ACL reconstructions and one hundred thirty-eight unilateral. The unilateral cohort included 69 (50.0%) males and 69 (50.0%) females and the bilateral cohort included 22 (51.2%) males and 21 (48.8%) females. Mean age was 26.0 (14-56) in the unilateral cohort and 25.2 (14-50) in the bilateral cohort. Mean BMI was 25 (15.3-39.2) in the unilateral cohort and 28 (15.1-39.7[SM1] ) in the bilateral cohorts (p=.08). The percentage of individuals who returned to sport in the bilateral reconstruction cohort was not significantly different from those who returned in the unilateral cohort (79.6% vs 76.7%, p=0.85). There was no significant difference in psychological readiness to RTS (mean score 52.6 for bilateral and 47.4 for unilateral, p=0.31). There was also no significant difference between the level at which bilateral versus unilateral patients returned to sport. 59.6% unilateral returned to the same or higher level and 60.6% bilateral returned to the same or higher level, p=0.92. There was no significant difference in the reported scale of psychological readiness to return to sport (52.6 for bilateral and 47.4 for unilateral, p=0.31). When asked about fear to RTS, the mean scale response was 42.2 in the unilateral cohort and 46.5 in the bilateral (p=0.45). Conclusions: There is no difference in RTS and level of sport returned to between patients who undergo bilateral ACL reconstructions compared to patients who undergo unilateral ACL reconstructions. Psychological readiness, fear and confidence to return to sport were not different between unilateral and bilateral injuries.

Posterior Tibial Slope in Patients Undergoing Bilateral Versus Unilateral ACL Reconstruction: MRI and Radiographic Analyses

Background: An increased posterior tibial slope (PTS) is a risk factor for primary anterior cruciate ligament (ACL) tears and graft failure, but the PTS has not been well-defined in those who have experienced bilateral ACL injuries. Purpose: The primary aim was to compare the PTS, as well as the rate of an elevated PTS (>12° on lateral radiography; >7° on magnetic resonance imaging [MRI]), between patients who have undergone bilateral ACL reconstruction (ACLR) versus unilateral ACLR. A secondary purpose was to examine whether these associations remained consistent on both plain radiography and MRI. Study Design: Cross-sectional study; Level of evidence, 3. Methods: We retrospectively identified patients who underwent primary ACLR at our institution from the years 2012 to 2020. Patients who underwent nonsimultaneous bilateral ACLR (n = 53) were matched to those who underwent unilateral ACLR (n = 53) by age, sex, and body mass index. Exclusion criteria were rotated lateral radiographs, MRI scans of inadequate quality, and concomitant ligament injuries or fractures. Those who had undergone unilateral ACLR with <5-year follow-up were further excluded. There were 3 blinded readers who measured the PTS on lateral radiographs, while the medial PTS (MPTS) and lateral PTS (LPTS) were measured on MRI scans. Bivariate regression was performed to determine the correlation between radiographic and MRI measurements. Results: The PTS on radiography (11.26° vs 10.13°, respectively; P = .044) and the LPTS on MRI (7.32° vs 6.08°, respectively; P = .012) in the bilateral ACLR group were significantly greater than those in the unilateral ACLR group but not the MPTS on MRI (4.55° vs 4.17°, respectively; P = .590). The percentage of patients in the bilateral group with a radiographic PTS >12° was 41.0% compared with 13.2% in the unilateral group (P = .012). The bilateral group had a significantly higher rate of an LPTS >7° compared with the unilateral group (53.8% vs 32.1%, respectively; P = .016) but not for an MPTS >7° (P = .190). On MRI, the LPTS (6.90°± 2.73°) was significantly greater than the MPTS (4.41°± 2.92°) (P < .001). There was a weak correlation between MPTS and radiographic PTS measurements (R = 0.24; P = .021), but LPTS and radiographic PTS measurements were not significantly correlated (R = 0.03; P = .810). Conclusion: Patients who underwent bilateral ACLR had a significantly greater PTS on radiography and a significantly greater LPTS on MRI compared with those who underwent unilateral ACLR. The rate of a radiographic PTS >12° was 2.4 times greater among patients undergoing bilateral ACLR compared with those undergoing unilateral ACLR. PTS measurements on radiography demonstrated a weak to negligible correlation with PTS measurements on MRI, suggesting that future normative PTS values should be reported specific to the imaging modality.

Comparison of Knee Function and Activity Level Between Bilateral and Unilateral ACL Reconstruction: A Matched-Group Analysis With Minimum 5-Year Follow-up.

Background:There is a lack of knowledge regarding knee function and activity level after bilateral anterior cruciate ligament reconstruction (ACLR) at midterm follow-up.Purpose:To compare activity level, patient-reported knee function, and quality of life in patients with bilateral ACLR and matched controls with unilateral ACLR at a minimum 5-year follow-up.Study Design:Cohort study; Level of evidence, 3.Methods:Patients with bilateral ACLR who were aged ≤40 years and had a second ACLR performed between 2010 and 2015 were identified in the authors’ local database. Surgical data and preoperative Knee injury and Osteoarthritis Outcome Score (KOOS) were extracted. The patients were sent a letter with questionnaires including the KOOS, EuroQol 5-Dimensions (EQ-5D), and EuroQol visual analog scale (EQ-VAS) and were asked study-specific questions by telephone regarding activity level and knee function at a minimum 5-year follow-up. For every patient with bilateral ACLR, a control matched for age ±2 years, sex, year ACLR was performed, and preinjury activity level or sport at the time of injury were identified in the database.Results:A total of 98 patients (mean age ± SD, 33.3 ± 7.3 years) with bilateral ACLR and 98 patients with unilateral ACLR (mean age ± SD, 33.1 ± 7.7 years) were included. The mean postoperative follow-up was 7.6 ± 1.8 years (from the second ACLR) for patients with bilateral ACLR and 7.8 ± 1.7 years for patients with unilateral ACLR. Patients with bilateral ACLR reported lower scores on all KOOS subscales, the EQ-5D, and the EQ-VAS at follow-up (P < .05). There was no difference in activity level between the groups at follow-up, but patients with bilateral ACLR were less satisfied with their activity level and knee function (P < .05).Conclusion:Patient-reported knee function and health-related quality of life were inferior in patients with bilateral ACLR compared with patients with unilateral ACLR. Patients with bilateral ACLR cannot expect the same knee function and quality of life as patients with unilateral ACLR.

Autologous Dedifferentiated Osteogenic Bone Marrow Mesenchymal Stem Cells Promote Bone Formation in a Rabbit Model of Anterior Cruciate Ligament Reconstruction versus Bone Marrow Mesenchymal Stem Cells

This study aimed to verify whether transplantation of dedifferentiated osteogenic bone marrow mesenchymal stem cells (De-BMSCs) at the tendon-bone interface could result in more bone formation than BMSC transplantation in anterior cruciate ligament (ACL) reconstruction. BMSCs from femur and tibia of New Zealand White rabbit were subjected to osteogenic induction and then cultured in osteogenic factor-free medium; the obtained cell population was termed De-BMSCs. Bilateral ACL reconstruction was performed in 48 adult rabbits. Three groups were established: control group with alginate gel injection, BMSCs group with the BMSCs injection, and De-BMSCs group with the De-BMSCs injection. At week 4 and 12 postoperatively, tendon-bone healing by histologic staining, micro-computed tomography examination, and biomechanical test were evaluated. The expression of α1 chain of type I collagen, osteocalcin, and osteopontin at the tendon-bone interface in the De-BMSCs group was greater than in the control or BMSCs group. The bone volume/total volume by micro-computed tomography scan was significantly greater in the De-BMSCs group than that in the control group (P= .013) or BMSCs group (P= .045) at 4 weeks, and greater than that in the control group (P= .014) or BMSCs group (P= .017) at 12 weeks. The tunnel area was significantly smaller in the De-BMSCs group than in the control group (P= .013) or BMSCs group (P= .044) at 12 weeks. The failure load and stiffness in De-BMSCs group were both significantly enhanced at 4 and 12 weeks than control group or De-BMSCs group. De-BMSCs transplantation can promote bone formation at the tendon-bone interface better than BMSCs transplantation in ACL reconstruction and increase the early biomechanical strength of the reconstructed ACL CLINICAL RELEVANCE: De-BMSCs transplantation is a potential choice for enhancing early bone formation in the tunnel in ACL reconstruction.

Return to Sport After Anterior Cruciate Ligament Reconstruction in a Cohort of Division I NCAA Athletes From a Single Institution.

Background:Anterior cruciate ligament (ACL) tears are common in collegiate athletes. The rate of return to the preinjury level of sport activities after ACL reconstruction continues to evolve.Purpose/Hypothesis:The purpose was to determine the return-to-sport rate after ACL reconstruction in a cohort of National Collegiate Athletic Association Division I athletes in different sports. It was hypothesized that, with intensive supervision of rehabilitation, the return-to-sport rate would be optimal.Study Design:Case series; Level of evidence, 4.Methods:We retrospectively reviewed the records of 75 collegiate athletes from a single institution who had undergone unilateral or bilateral ACL reconstruction between 2001 and 2013 and participated in an extensive supervised rehabilitation program. Prospectively collected athlete data as well as data about preinjury exposure, associated lesions, surgical technique, time lost to injury, number of games missed, time to return to full sport activity or retire, and subsequent surgical procedures were extracted from the medical and athletic trainer records.Results:The 75 patients (40 male, 35 female; mean age, 20.1 years) underwent 81 reconstruction procedures (73 primary, 8 revision). The mean follow-up was 19.3 months. The overall return-to-sport rate was 92%. After reconstruction, 9 athletes (12%) retired from collegiate sports, but 3 of them returned to sport activities after graduation. Overall, 8 athletes (11%) experienced an ACL graft retear.Conclusion:The return-to-sport rate in our National Collegiate Athletic Association Division I athletes compared favorably with that reported in other studies in the literature. The strict follow-up by the surgeon, together with the high-profile, almost daily technical and psychological support given mainly by the athletic trainers during the recovery period, may have contributed to preparing the athletes for a competitive rate of return to sport at their preinjury level.

Enhancement of tendon-bone interface healing and graft maturation with cylindrical titanium-web (TW) in a miniature swine anterior cruciate ligament reconstruction model: histological and collagen-based analysis

BackgroundTendon-bone interface healing and ligamentization of the graft in anterior cruciate ligament (ACL) reconstruction with autografts are important factors affecting treatment outcome. This study aimed to investigate the effectiveness of a cylindrical titanium-web (TW) in tendon-bone interface healing and graft maturation in ACL reconstruction.MethodsFourteen mature female CLAWN miniature swine underwent bilateral ACL reconstructions with patellar tendon (PT) autografts. In one limb, the TW/tendon complex was placed into the proximal side of the tibial tunnel. Only the graft was transplanted into the tunnel in the control limb. The proximal side of the graft was sutured into the stump of the native ACL and the distal end was stapled to the tibia. The animals were euthanized at 4 and 15 weeks postoperatively, for histological and biochemical analyses.ResultsMicroscopic images in TW limbs showed that ingrowth of tendon-like tissue and mineralized bone tissue into the TW connected the bone and the tendon directly. In contrast, fibrous tissue intervened between the bone and tendon in the control limbs. The total amount of collagen cross-links (which defines the strength of collagen fibers) and the maturation of collagen cross-links in TW tendons were significantly higher (p < 0.05) than those of control limbs. There was no significant difference in the ratio of dihydroxy-lysinonorleucine to hydroxy-lysinonorleucine (an indicator of tissue specific collagen maturation) between TW tendons and that of the native PT.ConclusionsTW promoted the maturation and formation of collagen cross-links in the grafted tendon while maintaining the cross-links pattern of native tendon collagen, and enabled direct binding of tendon to bone.

Low Rates of Return to Preinjury Sport After Bilateral Anterior Cruciate Ligament Reconstruction

Background: Patients with bilateral anterior cruciate ligament (ACL) injuries tend to report worse results in terms of knee function and quality of life as compared with those with unilateral injury. There are limited data regarding return to preinjury sport in this group. Purpose: To report return-to-sport rates for patients who had bilateral ACL reconstruction and to compare outcomes according to age and sex. Study Design: Case series; Level of evidence, 4. Methods: A total of 107 patients (62 male, 45 female) who underwent primary ACL reconstruction surgery to both knees completed a detailed sports activity survey at a mean 5-year follow-up (range, 2.5-10 years). Follow-up also included the International Knee Documentation Committee subjective form, Marx Activity Scale, and Knee injury and Osteoarthritis Outcome Score–Quality of Life subscale. Rates of return to preinjury levels of sport were calculated for the whole cohort, and for further analysis, the group was divided according to age (<25 vs ≥25 years), sex, and time between the reconstruction procedures (<3 vs ≥3 years). Results: The rate of return to preinjury sport after bilateral ACL reconstruction was 40% (95% CI, 31%-50%), as compared with an 83% (95% CI, 74%-88%) return rate after the first reconstruction procedure. Although not statistically significant, return rates were higher for male versus female patients (47% vs 31%) and older versus younger patients (45% vs 31%). Of those who returned to their preinjury levels of sport after the second reconstruction, 72% thought that they could perform as well as before their ACL injuries. In contrast, only 20% thought that they could perform as well if they returned to a lower level. Fear of reinjury was the most common reason cited for failure to return to sport after the second reconstruction. Patient-reported outcome scores were higher for those who returned to their preinjury levels of sport but did not differ for sex and age. Conclusion: Return-to-sport rates drop markedly after a second (contralateral) ACL reconstruction, with less than half of the investigated cohort returning to its preinjury level of sport. Return-to-sport outcomes are less than ideal for patients who have ACL reconstruction surgery to both knees.

Objectively Measured Physical Activity in Patients after ACL Reconstruction

Return to a healthy level of physical activity is a common clinical goal for patients recovering from anterior cruciate ligament reconstruction (ACLR). Objective measures of physical activity may provide useful information regarding achievement of rehabilitation goals in patients with ACLR. PURPOSE: To investigate differences in the average minutes per day (min/day) spent in moderate-to-vigorous physical activity (MVPA) as well as the total number of steps per day (steps/day) between individuals with ACLR and matched controls. A second purpose was to investigate relationships between MVPA and steps/day subjective activity scales Tegner and Marx activity scales. METHODS: Physical activity was assessed using ActiGraph accelerometers in 33 participants (22 females; 20.3±1.8 years; 171.8±10.5cm; 69.9±11.3kg; 27.8±17.5 months from surgery) with a history of primary unilateral or bilateral ACLR as well as 33 healthy controls (CON) (20.8±1.6 years; 172.9±8.5cm; 70.2±13.5kg) (matched on age, sex, and Tegner activity level). Participants wore the accelerometer for 7 consecutive days and completed the IKDC 2000 subjective form and the Tegner and Marx activity scales. Independent t-tests were used to examine between group differences. Bivariate correlation coefficients were calculated between objective and subjective activity levels. RESULTS: Patients with ACLR participated in less MVPA per day (ACLR: 78.3±26.6 min/day; CON: 94.2±26.6 min/day; P=0.02) and less steps/day (ACLR: 7,982±3,020 steps/day; CON: 9,945±2,885 steps/day; P=0.02) compared to healthy matched controls. Only 25% of participants with ACLR met the 10,000 steps/day guidelines compared to 42% of controls. However, Marx (ACLR: 10.2±4.8; CON: 10.8±3.8; P=0.63) and Tegner (ACLR: 6.2±2.1; CON: 6.7±1.7; P=0.11) activity levels did not differ between groups. No relationships were observed between objectively measured physical activity and scale measures (P>0.05). CONCLUSIONS: Patients with ACLR accumulate less MVPA and fewer steps/day compared to highly matched controls despite reporting similar subjective activity levels. These findings highlight the importance of objective monitoring of physical activity level following return to activity due to the potential risk associated with reduced levels of physical activity.

Objectively Measured Physical Activity in Patients After Anterior Cruciate Ligament Reconstruction

Background: Returning to a healthy level of physical activity is among the most commonly discussed clinical goals for patients recovering from anterior cruciate ligament reconstruction (ACLR). However, physical activity has not been objectively measured in this population. Purpose: To investigate differences in the mean time (min/d) spent in moderate-to-vigorous physical activity (MVPA) as well as the daily step count (steps/d) between patients who underwent ACLR and matched controls. A second purpose was to investigate relationships between MVPA and objective assessments of the daily step count and Tegner and Marx activity scales. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Physical activity was assessed using ActiGraph accelerometers in 33 participants with a history of primary unilateral or bilateral ACLR (mean time from surgery, 27.8 ± 17.5 months; range, 6-67 months) as well as in 33 healthy controls (matched on age, sex, and activity level). Participants wore the accelerometer for 7 days and completed the International Knee Documentation Committee subjective form and the Tegner and Marx activity scales. Independent t tests were used to determine differences in each dependent variable per group. Results: Patients who underwent ACLR spent less time in MVPA (ACLR: 79.37 ± 23.95 min/d; control: 93.12 ± 23.94 min/d; P = .02) and had a lower daily step count (ACLR: 8158 ± 2780 steps/d; control: 9769 ± 2785 steps/d; P = .02) compared with healthy matched controls. However, the Marx (ACLR median: 11.0 [interquartile range (IQR), 7-14]; control median: 12.0 [IQR, 8-13]; P = .85) and Tegner (ACLR median: 6.0 [IQR, 5-8]; control median: 7.0 [IQR, 6-8]; P = .12) scores did not differ between the groups, and no relationships were observed between objectively measured physical activity and scale measures (P > .05), except for a moderate relationship between the Tegner score and daily step count in the ACLR group (r = 0.36, P = .04). Only 24% of patients who underwent ACLR met the guideline of 10,000 steps per day compared with 42% of controls. Conclusion: Patients who underwent ACLR spent less time in MVPA and had a lower daily step count compared with highly matched controls (age, sex, and activity level) with no history of knee injuries. This was true despite being similar in activity levels, which brings into question the utility of the Tegner and Marx activity scales.

Anterior Cruciate Ligament–Derived Stem Cells Transduced With BMP2 Accelerate Graft-Bone Integration After ACL Reconstruction

Background: Strong graft-bone integration is a prerequisite for successful graft remodeling after reconstruction of the anterior cruciate ligament (ACL) using soft tissue grafts. Novel strategies to accelerate soft tissue graft-bone integration are needed to reduce the need for bone-tendon-bone graft harvest, reduce patient convalescence, facilitate rehabilitation, and reduce total recovery time after ACL reconstruction. Hypothesis: The application of ACL-derived stem cells with enhanced expression of bone morphogenetic protein 2 (BMP2) onto soft tissue grafts in the form of cell sheets will both accelerate and improve the quality of graft-bone integration after ACL reconstruction in a rat model. Study Design: Controlled laboratory study. Methods: ACL-derived CD34+ cells were isolated from remnant human ACL tissues, virally transduced to express BMP2, and embedded within cell sheets. In a rat model of ACL injury, bilateral single-bundle ACL reconstructions were performed, in which cell sheets were wrapped around tendon autografts before reconstruction. Four groups containing a total of 48 rats (96 knees) were established (n = 12 rats; 24 knees per group): CD34+BMP2 (100%), CD34+BMP2 (25%), CD34+ (untransduced), and a control group containing no cells. Six rats from each group were euthanized 2 and 4 weeks after surgery, and each graft was harvested for immunohistochemical and histological analyses. The remaining 6 rats in each group were euthanized at 4 and 8 weeks to evaluate in situ tensile load to failure in each femur-graft-tibia complex. Results: In vitro, BMP2 transduction promoted the osteogenic differentiation of ACL-derived CD34+ cells while retaining their intrinsic multipotent capabilities. Osteoblast densities were greatest in the BMP2 (100%) and BMP2 (25%) groups. Bone tunnels in the CD34+BMP2 (100%) and CD34+BMP2 (25%) groups had the smallest cross-sectional areas according to micro–computed tomography analyses. Graft-bone integration occurred most rapidly in the CD34+BMP2 (25%) group. Tensile load to failure was significantly greater in the groups containing stem cells at 4 and 8 weeks after surgery. Tensile strength was greatest in the CD34+BMP2 (100%) group at 4 weeks, and in the CD34+BMP2 (25%) group at 8 weeks. Conclusion: ACL-derived CD34+ cells transduced with BMP2 accelerated graft-bone integration after ACL reconstruction using soft tissue autografts in a rat model, as evidenced by improved histological appearance and graft-bone interface biology along with tensile load to failure at each time point up to 8 weeks after surgery. Clinical Relevance: A primary disadvantage of using soft tissue grafts for ACL reconstruction is the prolonged time required for bony ingrowth, which delays the initiation of midsubstance graft remodeling. The lack of consistent correlation between the appearance of a “healed” ACL on postoperative magnetic resonance imaging and readiness to return to sport results in athletes being released to sport before the graft is ready to handle high-intensity loading. Therefore, it is desirable to identify strategies that accelerate graft-bone integration, which would reduce the time to biologic fixation, improve the reliability of biologic fixation, allow for accelerated rehabilitation, and potentially reduce the incidence of early graft pullout and late midsubstance failure.

Relationship Between Posterior-Inferior Tibial Slope and Bilateral Noncontact ACL Injury.

Is there a correlation between increased posterior-inferior tibial slope angle and noncontact anterior cruciate ligament (ACL) injury? Does increasing the posterior-inferior tibial slope angle increase the risk of bilateral ACL injury? A computerized relational database (Access 2007; Microsoft Inc, Redmond, Washington) was used to conduct a retrospective review of patients undergoing bilateral or unilateral ACL reconstruction surgery or treatment by a single surgeon between 1995 and 2013. Included in the study were patients with bilateral and unilateral ACL injuries and patellofemoral pain syndrome with no associated ACL deficiency. Exclusion criteria included concomitant ligament injury, previous ACL reconstruction, and previous knee surgery. Also excluded were patients who did not have plain lateral radiographs. Fifty patients were randomly selected from each group. After controlling for age and Tegner activity level, the authors found that the posterior-inferior tibial slope angle was a significant predictor (P=.002) of noncontact ACL injury. Mean posterior-inferior tibial slope angle for the bilateral, unilateral, and control groups was 11.8°±2.3°, 9.3°±2.4°, and 7.5°±2.3°, respectively. In the group with unilateral ACL injury vs the group without ACL deficiency, a 1° increase in posterior-inferior tibial slope angle (P=.03) was associated with a 20% increase in unilateral ACL injury. In those with bilateral ACL injury vs those without ACL deficiency, a 1° increase in posterior-inferior tibial slope angle (P=.001) increased bilateral knee injury by 34%. The difference between the mean angles of the control group without ACL deficiency and both the bilateral injury and unilateral injury cohorts was statistically significant (P=.003). Increased posterior-inferior tibial slope angle is associated with an increased risk of noncontact bilateral and unilateral ACL injury. [Orthopedics. 2017; 40(1):e136-e140.].

The Utility of Limb Symmetry Indices in Return-to-Sport Assessment in Patients With Bilateral Anterior Cruciate Ligament Reconstruction

Background: The incidence of contralateral anterior cruciate ligament (ACL) injury after ACL reconstruction (ACLR) is high. Often, return-to-sport (RTS) tests of strength and functional hopping rely on limb symmetry indices (LSIs) to identify deficits, although the utility of these measures in athletes with bilateral ACL injuries is unknown. Purpose/Hypothesis: The aim of this study was to investigate if LSIs used as RTS criteria in female patients after unilateral ACLR were appropriate for female patients with bilateral ACL involvement. The hypothesis tested was that asymmetries with traditional LSI measures would be present in a population after unilateral ACLR but would not be present in a population with bilateral ACLR due to the lack of a healthy internal control limb. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 45 female subjects were classified into 3 groups: after second (contralateral) ACLR (ACLR-B; n = 15); after primary unilateral ACLR (ACLR-U; n = 15); and uninjured controls (CTRL; n = 15). After being cleared for RTS, each subject completed a single-legged hop for distance (SLHD), triple hop for distance (THD), and triple-crossover hop for distance (CHD) test, in addition to an isometric quadriceps strength test on both limbs. Means and LSI ([involved limb/uninvolved limb] × 100) were calculated for each test. Limb symmetry deficits were defined by LSI <90%. Results: Analysis of functional hop testing revealed a side × group interaction for SLHD (P = .001), THD (P = .019), and CHD (P = .04). Side-to-side differences were found in the ACLR-U group for all hop tests (P = .001-.003) and in the ACLR-B group for SLHD (P = .002) and THD tests (P = .024). No side-to side differences were seen in the CTRL group (P > .05). A side × group interaction was found for isometric quadriceps strength (P = .006), with lower LSI seen in the ACLR-U group (81% ± 17.6%) compared with the CTRL group (102.2% ± 10.8%) and the ACLR-B group (95.6% ± 24.9%). Although no interaction was seen, side-to-side differences were noted in the THD in the ACLR-U group (P = .013) and ACLR-B group (P = .024) and in the CHD in the ACLR-U group (P = .001). Despite absence of an LSI deficit, bilateral peak quadriceps strength in the ACLR-B group was comparable to the involved limb of the ACLR-U group and less than in the CTRL group (P = .012). Conclusion: Both the ACLR-U and the ACLR-B groups demonstrated side-to-side deficits during functional hop tests; however, these deficits were not identified according to the clinically accepted LSI values of ≥90%, calling into question the efficacy of current RTS criteria. At the time of RTS, only individuals in the ACLR-U group demonstrated an altered LSI in quadriceps strength. Significantly lower quadriceps strength of both limbs in the ACLR-B group was seen compared with the CTRL group, despite no LSI deficits in quadriceps strength. Current use of LSIs during strength and performance tests may not be an appropriate means of identifying residual deficits in female patients after bilateral ACLR at time of RTS. Furthermore, a better indicator of strength performance in this population may need to include a comparison of strength performance values to the normative values of healthy controls.

Validity of the twitch interpolation technique for the assessment of quadriceps neuromuscular asymmetries

This study examined the validity of the twitch interpolation technique for evaluating side-to-side asymmetries in quadriceps neuromuscular function. Fifty-six subjects with a wide range of asymmetries (19 healthy, 24 with unilateral and 13 with bilateral anterior cruciate ligament reconstruction) took part in the study. Supramaximal electrical paired stimuli were delivered to the quadriceps muscle during and immediately after a maximal voluntary contraction (MVC) of the knee extensors (twitch interpolation technique). MVC torque, voluntary activation and resting doublet-evoked torque were measured separately for the two sides, and percent side-to-side asymmetries were calculated for each parameter. MVC torque asymmetry was plotted against voluntary activation asymmetry and doublet-evoked torque asymmetry, and a multiple regression analysis was also conducted. Significant positive correlations were observed between MVC torque asymmetry and both voluntary activation asymmetry (r=0.40; p=0.002) and doublet-evoked torque asymmetry (r=0.53; p<0.001), and their relative contribution to MVC torque asymmetry was comparable (r=0.64; p<0.001). These results establish the validity of the twitch interpolation technique for the assessment of neuromuscular asymmetries. This methodology could provide useful insights into the contribution of some neural and muscular mechanisms that underlie quadriceps strength deficits.

Bilateral ACL Reconstructions with Hamstring Autografts.

Bilateral anterior cruciate ligament (ACL) injuries are rare with incidence between 2 and 4%, and presently no definitive guidelines for proper management exist. Ideal treatment protocol remains controversial between a single-stage and two-stage bilateral ACL reconstruction. The purpose of this study is to evaluate the outcome of single-stage bilateral ACL reconstruction with hamstring tendon autografts in bilateral ACL injuries. A prospective study was undertaken including a total of 14 consecutive patients with bilateral ACL deficient knee who underwent single-stage bilateral ACL reconstruction with hamstring tendon autograft with a mean follow-up duration of 28 months (24-38 months). Functional outcomes were evaluated by range of movements, International Knee Documentation Committee (IKDC), Lysholm and Tegner activity score, and stability tests. The mean age was 30 years (range 18-42 years). Average duration of rehabilitation was 8 weeks. Time to return to full-time work and full sports was 5.6 weeks and 6.2 months, respectively. Clinical examination demonstrated full range of motion; a total of 12 patients (86%) had a negative Lachman test and 13 patients (93%) had a negative pivot shift at the final follow-ups. The mean IKDC evaluation score was 89 points, the mean Tegner activity score was 7 points, and the mean Lysholm knee score was 91 points. A total of 12 patients (86%) returned to their preinjury level of activity and an overall greater than 90% satisfaction rate was achieved. Single-stage bilateral ACL reconstruction using hamstring autografts is clinically safe, effective, and cost-effective with better patient compliance and with comparable functional outcome as opposed to two-stage ACL reconstructions.

Economic Analyses in Anterior Cruciate Ligament Reconstruction

Background: As the health care system in the United States (US) transitions toward value-based care, there is an increased emphasis on understanding the cost drivers and high-value procedures within orthopaedics. To date, there has been no systematic review of the economic literature on anterior cruciate ligament reconstruction (ACLR). Purpose: To evaluate the overall evidence base for economic studies published on ACLR in the orthopaedic literature. Data available on the economics of ACLR are summarized and cost drivers associated with the procedure are identified. Study Design: Systematic review. Methods: All economic studies (including US-based and non–US-based) published between inception of the MEDLINE database and October 3, 2014, were identified. Given the heterogeneity of the existing evidence base, a qualitative, descriptive approach was used to assess the collective results from the economic studies on ACLR. When applicable, comparisons were made for the following cost-related variables associated with the procedure for economic implications: outpatient versus inpatient surgery (or outpatient vs overnight hospital stay vs >1-night stay); bone–patellar tendon–bone (BPTB) graft versus hamstring (HS) graft source; autograft versus allograft source; staged unilateral ACLR versus bilateral ACLR in a single setting; single- versus double-bundle technique; ACLR versus nonoperative treatment; and other unique comparisons reported in single studies, including computer-assisted navigation surgery (CANS) versus traditional surgery, early versus delayed ACLR, single- versus double-incision technique, and finally the costs of ACLR without comparison of variables. Results: A total of 24 studies were identified and included; of these, 17 included studies were cost identification studies. The remaining 7 studies were cost utility analyses that used economic models to investigate the effect of variables such as the cost of allograft tissue, fixation devices, and physical therapy, the percentage and timing of revision surgery, and the cost of revision surgery. Of the 24 studies, there were 3 studies with level 1 evidence, 8 with level 2 evidence, 6 with level 3 evidence, and 7 with level 4 evidence. The following economic comparisons were demonstrated: (1) ACLR is more cost-effective than nonoperative treatment with rehabilitation only (per 3 cost utility analyses); (2) autograft use had lower total costs than allograft use, with operating room supply costs and allograft costs most significant (per 5 cost identification studies and 1 cost utility analysis); (3) results on hamstring versus BPTB graft source are conflicting (per 2 cost identification studies); (4) there is significant cost reduction with an outpatient versus inpatient setting (per 5 studies using cost identification analyses); (5) bilateral ACLR is more cost efficient than 2 unilateral ACLRs in separate settings (per 2 cost identification studies); (6) there are lower costs with similarly successful outcomes between single- and double-bundle technique (per 3 cost identification studies and 2 cost utility analyses). Conclusion: Results from this review suggest that early single-bundle, single (endoscopic)-incision outpatient ACLR using either BPTB or HS autograft provides the most value. In the setting of bilateral ACL rupture, single-setting bilateral ACLR is more cost-effective than staged unilateral ACLR. Procedures using CANS technology do not yet yield results that are superior to the results of a standard surgical procedure, and CANS has substantially greater costs.

QUALITY OF LIFE AFTER BILATERAL ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTIONS.

The aim of study was to analyze the influence of bilateral anterior cruciate ligament reconstructions on life quality of patients and their return to sports activities. Thirty-two operated patients took part in this survey during the period of ten years. There were 5 women and 27 men, their average age being 30.46 years (19-55). The participants answered a modified Knee Injury and Osteoarthritis Outcome Score questionnaire set and gave data about preoperative and postoperative periods. The participants' age and parameters of Lysholm scale did not correlate significantly with the subjective level of physical activity after the second knee surgery. After the first anterior cruciate ligament reconstruction, 4 participants (12.5%) did not return to trainings, while 28 did (87.5%); 8 patients (25%) did not return to competitions and 24 of them (75%) achieved the competition level of sports activities. After the anterior cruciate ligament reconstruction of contralatera knee, 6 (18.8%) did not return to trainings, while 26 (81.3%) did; 15 patients (46.9%) did not return to competitions, while 17 (53.1% continued to compete without restrictions. The average values of questionnaire scores were between 95.1-98.2 points. Discussion and Resuming the same or higher level of sports activitie., after the first reconstruction is one of the preconditions for the same injury of another knee. An athlete looses more than two and a half years of competitions on average. Operations of additional meniscu ruptures do not play a crucial role in restitution of sports activities Although we achieved good operative results, only every seconc athlete with bilateral injury has returned to sports activities withou restrictions after the bilateral anterior cruciate reconstructions.

Bilateral agenesis of the anterior cruciate ligament: MRI evaluation

Bilateral agenesis of the anterior cruciate ligament (ACL) is extremely rare. We describe a 13-year-old girl who presented with bilateral knee pain without history of trauma; she has two family members with knee instability. Magnetic resonance imaging showed bilateral absence of the ACL, and medial posterior horn meniscal tears. Bilateral arthroscopic partial meniscectomy and anterior cruciate ligament reconstruction was performed.