Self-Reported Patient Outcomes after ACL Reconstruction with Allograft Tissue

Females Have Earlier Muscle Strength and Functional Recovery After Bridge-Enhanced Anterior Cruciate Ligament Repair

Background: While a sex effect on outcomes following anterior cruciate ligament (ACL) reconstruction surgery has been previously documented, less is known following bridge-enhanced ACL repair (BEAR). We hypothesized that female sex would have significantly worse early functional outcomes and higher retear rates following primary repair of the ACL enhanced with a tissue-engineered scaffold. Methods: Sixty-five patients (28 males and 37 females), age 14-35 with a complete ACL tear underwent primary repair of the ACL enhanced with a tissue-engineered scaffold (bridge-enhanced ACL repair) within 45 days of injury. International Knee Documentation Committee (IKDC) and Knee Injury and Osteoarthritis Outcome (KOOS) scores, as well as instrumented anteroposterior (AP) laxity through KT-1000 testing and functional outcome measures were obtained at time points up to 2 years postoperatively and compared between males and females using mixed model repeated measures analyses and chi square tests. Results: There was no significant sex difference on the postoperative IKDC Subjective Score at 3, 6, 12, or 24 months or any of the five KOOS scores at 12 and 24 months. Instrumented AP laxity testing demonstrated mean (standard deviation) side-to-side differences that were similar in the two sexes at 2 years; 1.7 (2.7) mm and 1.5 (3.7) mm in females and males, respectively, p = 0.72. At 6 months postoperatively, males had a larger deficit in hamstring strength on the operated leg (14.0% vs. 1.7%; p = 0.03) and a larger deficit in quadriceps strength on the operated leg (11.3% vs. 2.0%; p = 0.004); however, no sex difference was noted at 12 or 24 months. Females demonstrated superior single leg hop testing at 6 and 12 months ([91.3% vs. 78.1%, p = 0.001], [96.9% vs. 87.0%, p = 0.01] respectively). There were no significant sex differences on ipsilateral (males; 14.3% vs. females; 13.9%, p = 1.00) or contralateral (males; 3.6% vs. females; 2.8%, p = 1.00) ACL reinjury rates. Conclusions: Female subjects had better hamstring and quadriceps strength indices at 6 months than males as well as better hop test results at the 6 and 12-month time period. Despite this, there was no significant sex difference on patient-reported outcomes and objective AP laxity testing at time points up to 2 years postoperatively. Impact statement This is the first study comparing sex specific outcomes following the bridge-enhanced ACL repair technique (BEAR). The results of this study suggest that females have earlier recovery of both muscle strength and functional outcomes compared to their male counterparts. This is an important finding when considering future modifications to postoperative care and rehabilitation in females and males following this tissue-engineered BEAR technique.

Self-reported outcomes are associated with knee strength and functional symmetry in individuals who have undergone anterior cruciate ligament reconstruction with hamstring tendon autograft

BACKGROUND

The aim of this study was to investigate the relationship between self-reported knee outcomes and limb symmetry indices (LSIs) for hip and knee strength, postural control and single-leg hop distance in individuals who had undergone an anterior cruciate ligament (ACL) reconstruction via hamstring tendon autograft (HTG).

METHODS

A total of 72 participants with a history of unilateral ACL reconstruction via HTG (mean ± standard deviation (SD) age: 28.0 ± 7.6 years; height: 178.4 ± 6.7 cm; mass 76.9 ± 14.9 kg) were included. International Knee Documentation Committee 2000 Subjective Knee Form (IKDC), Lysholm, Knee Osteoarthritis Outcomes Scores (KOOS) and Tampa scores were used to evaluate self-reported outcomes. Concentric and eccentric knee extensor and flexor, and hip strength, postural control and single leg hop distance were evaluated for performance-based outcomes. The relationships between the LSI scores and the performance measures were explored using the Pearson correlation coefficient.

RESULTS

The IKDC, Lysholm and KOOS scores were positively correlated with knee extensor and flexor strength LSIs (P < 0.05, r = 0.34 to r = 0.50), and the Tampa score was negatively correlated with eccentric extensor LSI (P = 0.02, r = -0.34). Single-leg hop distance LSI was correlated with IKDC and Lysholm scores (P = 0.003, r = 0.50; P = 0.04, r = 0.29) respectively, while postural control was only correlated with the KOOS scores (P < 0.001, r = 0.51 to r = 0.52).

CONCLUSIONS

Compared to Lysholm and Tampa scores, KOOS and IKDC scores were more likely to be correlated with performance-based outcomes. Therefore, KOOS and IKDC scores may help clinicians in return to sport decision making when there is a limited time to perform extensive evaluations or access equipment.

The Importance of Patient Sex in the Outcomes of Anterior Cruciate Ligament Reconstructions: A Systematic Review and Meta-analysis

BACKGROUND

One of the well-studied epidemiological phenomena of anterior cruciate ligament (ACL) injuries is the 2- to 9-fold increase in the relative risk of ACL rupture in female athletes compared with male athletes. However, the influence of patient sex on the outcome after ACL reconstruction remains unclear, with some authors reporting inferior outcomes in females and others noting no significant difference.

PURPOSE

To provide a comprehensive systematic review and meta-analysis to examine the possible association between patient sex and the subjective and objective outcomes after ACL reconstruction.

METHODS

This study was conducted according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. All studies that reported clinical outcomes after ACL reconstruction in males and females independently were included in the review. A quantitative random-effects meta-analysis was performed to compare outcomes between sexes. For outcomes with considerable heterogeneity, meta-regression was used to identify potential moderators. Articles were evaluated qualitatively when quantitative data were not reported.

RESULTS

A total of 135 publications were included in the review. Females had inferior outcomes in instrumented laxity (standardized mean difference [SMD], 0.24; 95% CI, 0.11-0.37), revision rate (relative risk [RR], 1.15; 95% CI, 1.02-1.28), Lysholm score (SMD, -0.33; 95% CI, -0.55 to -0.11), Tegner activity scale (SMD, -0.37; 95% CI, -0.49 to -0.24), and incidence of not returning to sports (RR, 1.12; 95% CI, 1.04-1.21), all of which were statistically significant. Other outcomes were comparable between sexes, including anterior drawer test, Lachman test, pivot-shift test, timed single-legged hop test, single-legged hop test, quadriceps testing, hamstring testing, extension loss, flexion loss, development of cyclops lesion, and International Knee Documentation Committee (IKDC) knee examination score. Females and males were equally likely to develop anterior knee pain and osteoarthritis after ACL reconstruction. The graft rupture and graft failure rates did not differ significantly between sexes.

CONCLUSION

There were comparable or inferior results for females compared with males in all outcomes analyzed. No statistically significant sex difference was identified in most of the objective parameters. However, subjective and functional outcomes, including Lysholm score, Tegner activity scale, and ability to return to sports, have been shown to be poorer in females.

Lower extremity neuromuscular compensations during instrumented single leg hop testing 2-10 years following ACL reconstruction

BACKGROUND

This study compared lower extremity EMG activation and sagittal plane kinematics of subjects at a minimum of 2 years post-successful ACL reconstruction and rehabilitation during instrumented single leg hop testing.

METHODS

Comparisons were made based on subject responses to the following question, "compared to prior to your knee injury how capable are you now in performing sports activities"? Group 1=very capable, Group 2=capable, and Group 3=not capable. In addition to EMG (1000 Hz) and kinematic (60 Hz) data, subjective knee function, internal health locus of control, sports activity characteristics (intensity, frequency) pre-knee injury, and at follow-up were also compared.

RESULTS

Group 3 had lower perceived knee function, decreased perceived sports intensity, and more subjects with decreased sports activity intensity by two levels compared to pre-injury values. Perceived function scores, anterior laxity measurements and grades were similar between groups. During single leg hop propulsion and landing Group 1 (very capable) had greater involved lower extremity gluteus maximus and medial hamstring activation amplitudes than Group 3 (not capable). Perceived sports capability was related to better subjective knee function, and higher perceived sports activity intensity.

CONCLUSION

Neuromuscular compensations suggesting a hip bias with increased gluteus maximus and medial hamstring activation were identified at the involved lower extremity among most subjects who perceived high perceived sports capability compared to pre-injury status. These compensations may be related to a permanent neurosensory deficit, and its influence on afferent pathway changes that influence CNS sensorimotor re-organization.

Outcomes of Schatzker II tibial plateau fracture open reduction internal fixation using structural bone allograft

OBJECTIVES

The purpose of this study is to report the rate of anatomic reduction, articular subsidence, and clinical outcomes for Schatzker II tibial plateau fractures treated with structural bone allografts.

DESIGN

This is a retrospective case series.

SETTING

Academic Level I Trauma Center.

PATIENTS/PARTICIPANTS

A trauma registry was used to identify 77 Schatzker II tibial plateau fractures.

INTERVENTION

Schatzker II tibial plateau fracture open reduction internal fixation and structural bone graft using either Plexur P (N = 29) or fibular allograft (N = 48).

MAIN OUTCOME MEASUREMENT

The primary outcome was articular subsidence. Secondary outcomes included fracture malreduction and clinical outcomes including the Knee Outcome Survey Activities of Daily Living Scale, the Lower Extremity Functional Scale, and the Short Form (SF)-36.

RESULTS

No patients experienced subsidence > 2mm. This rate is significantly lower than published rates for autogenous iliac crest (30.3%, P < 0.0001) and calcium phosphate cement (8.7%, P = 0.0099). The rate of fracture malreduction was 11.7% (9/77); only 4 had more than 3 mm of residual incongruity. Average outcome scores were the following: Knee Outcome Survey Activities of Daily Living Scale, 81.7; Lower Extremity Functional Scale, 78.5; SF-36 physical component, 48.3; and SF-36 mental component, 53.1. There was no difference between patients treated with Plexur P or fibula with regard to the primary or secondary outcomes.

CONCLUSIONS

The use of structural allograft resulted in a high rate of anatomic reduction and negligible rate of articular subsidence and good clinical outcomes in the treatment of this population of Schatzker II tibial plateau fractures. This compares favorably with historical results using nonstructural grafts.

LEVEL OF EVIDENCE

Therapeutic level IV. See instructions for authors for a complete description of levels of evidence.

Sports involvement following ACL reconstruction is related to lower extremity neuromuscular adaptations, subjective knee function and health locus of control

PURPOSE

This retrospective study compared the influence of perceived sports involvement on lower extremity neuromuscular adaptations during single-leg countermovement jumping (CMJ), perceived knee function and internal health locus of control (HLOC) scores at a minimum 2-year post-anterior cruciate ligament reconstruction. The hypothesis was that subjects with higher-level sports involvement would display significant differences compared to subjects with lower-level sports involvement.

METHODS

Uninvolved and involved lower extremity EMG amplitude (1,000 Hz), vertical ground reaction force (VGRF) (500 Hz) and kinematic (60 Hz) displacement differences were determined during single-leg CMJ. These data and International Knee Documentation Committee subjective knee survey scores, Multidimensional Health Locus of Control Survey internal HLOC subscale scores and sports activity characteristics were compared by sports involvement level.

RESULTS

Subjects that regarded themselves as only sporting sometimes (Group 3, n = 26) had lower IKDC survey and internal HLOC scores, were more likely to decrease sports activities by two intensity levels than highly competitive (Group 1, n = 20) and well-trained/frequently sporting (Group 2, n = 24) subjects, and had greater peak landing VGRF differences suggesting decreased involved lower extremity loading compared to Group 2. During propulsion, Group 1 had greater gluteus maximus (GM) and gastrocnemius (G) EMG differences than Groups 2 and 3. Groups 1 and 2 had decreased vastus medialis (VM) EMG differences during propulsion than Group 3. During landing, Group 1 had greater GM and G EMG differences than Group 3.

CONCLUSION

Subjects with higher-level sports involvement up-regulated involved lower extremity GM and G activation and down-regulated VM activation. This adaptation may enable continued higher-level sports participation while minimizing knee joint forces. Perceived higher-level sports involvement was related to neuromuscular adaptations, better subjective knee function, a more internal HLOC and higher sports activity intensity.

LEVEL OF EVIDENCE

Therapeutic case series, level IV.

Clinical Outcomes and Return-to-Sports Participation of 50 Soccer Players After Anterior Cruciate Ligament Reconstruction Through a Sport-Specific Rehabilitation Protocol

Background:

Rehabilitation of soccer players after anterior cruciate ligament reconstruction is usually performed without sport-specific guidelines, and the final phases are often left to the team coaches. The possibility of changing this approach has not yet been investigated.

Study Design:

Case series.

Hypothesis:

A specific rehabilitation protocol for soccer players, with direct control of the last on-field rehabilitation phases, may lead to complete functional recovery.

Methods:

Fifty competitive soccer players who followed a sport-specific rehabilitation protocol for soccer were evaluated during the recovery period until their return to competition. The assessment of the functional outcomes was performed using the Knee Outcome Survey–Sports Activity Scale and isokinetic and aerobic fitness tests.

Results:

The average start of on-field rehabilitation was 90 ± 26 days after surgery; the average time to return to the competitions was 185 ± 52 days. The improvement in the Knee Outcome Survey–Sports Activity Scale during on-field rehabilitation was significant (P < 0.01; from 79 ± 15% to 96 ± 7%). The isokinetic and aerobic fitness tests showed a significant improvement of muscle strength (knee extensors, +55%, P < 0.01; knee flexors, +86%, P < 0.01) and aerobic threshold (+23%, P < 0.01) from the beginning to the end of on-field rehabilitation.

Conclusions:

Adding on-field rehabilitation to the traditional protocols after anterior cruciate ligament reconstruction may safely lead to complete functional recovery in soccer players.

Anterior cruciate ligament allograft surgery: underreporting of graft source, graft processing, and donor age

BACKGROUND

There has been much controversy regarding the effects of sterilization techniques and graft history on the structural integrity of allograft ligaments used in reconstruction of the anterior cruciate ligament. The purpose of this review was to comprehensively examine anterior cruciate ligament allograft studies published in the last decade to evaluate the extent to which tissue source, tissue processing techniques, and donor age are reported.

METHODS

The authors reviewed 202 articles published from 1999 through November 2009, of which 68 retrospective, prospective, biomechanical, and histology studies evaluating 4689 allografts were included.

RESULTS

The majority of studies do not accurately report key elements of graft history including tissue bank, processing or sterilization technique, or donor age. Underreporting was particularly prominent in clinical studies as compared with basic science studies. Limited reporting of allograft processing, allograft source, and donor age raises serious questions regarding the generalizability of published studies of allograft tissue for anterior cruciate ligament reconstruction. Conclusion/

CLINICAL RELEVANCE

Orthopaedic surgeons who use allograft tissue must understand the tissue treatments being used (ie, preservation methods, chemical and sterilization processes) to best inform their patients regarding the risks, benefits, and long-term outcomes when such tissues are used. A complete understanding of the implanted tissue, as well as surgeon and recipient demographics, is necessary to ensure appropriate and predictable long-term outcomes.

Lower extremity compensatory neuromuscular and biomechanical adaptations 2 to 11 years after anterior cruciate ligament reconstruction

PURPOSE

To determine whether compensatory neuromuscular and biomechanical adaptations exist after successful anterior cruciate ligament reconstruction and rehabilitation.

METHODS

Seventy subjects, 5.3 +/- 3 years after surgery, participated in this study. Sagittal-plane lower extremity kinematic, gluteus maximus, vastus medialis, medial hamstring, and gastrocnemius electromyography (EMG) and vertical ground reaction force data were collected during single-leg countermovement jump (CMJ) performance.

RESULTS

Women had lower propulsive and landing forces, lower CMJ heights, less hip and knee flexion, and greater angular hip, knee, and ankle velocities than men (P < or = .014). The involved lower extremity of men and women had decreased landing forces (P = .008). During propulsion, men and women had increased involved-lower extremity gluteus maximus (P < .0001) and decreased vastus medialis (P = .013) EMG amplitudes, whereas women had bilaterally increased gastrocnemius EMG amplitudes compared with men (P = .003). During propulsion, men had longer gluteus maximus and vastus medialis EMG durations than women (P < .0001). During landing, both men and women had increased gluteus maximus EMG amplitudes at the involved lower extremity (P < .0001). Women had increased vastus medialis (P = .01) and gastrocnemius (P < .0001) EMG amplitudes compared with men. During landing, men had longer gluteus maximus (P = .004), vastus medialis (P = .012), and gastrocnemius (P = .007) EMG durations than women and the involved-lower extremity vastus medialis EMG durations of both men and women were shorter than at the noninvolved lower extremity (P = .011).

CONCLUSIONS

Decreased involved-lower extremity landing forces, decreased vastus medialis activation, and increased gluteus maximus and gastrocnemius activation suggest a protective mechanism to minimize knee loads that increase anterior translatory knee forces during single-leg jumping. Women showed more balanced gluteus maximus, vastus medialis, and gastrocnemius contributions to dynamic knee stability than men during CMJ landings but used shorter activation durations.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Biomechanical and tissue handling property comparison of decellularized and cryopreserved tibialis anterior tendons following extreme incubation and rehydration

Little is known regarding the biomechanical profiles and tissue handling properties of decellularized and cryopreserved human tibialis anterior tendons prepared as allografts for ACL reconstruction. This study compared allografts prepared using two extremes of the same cryoprotectant incubation and rehydration technique with a standardly prepared control group. Porcine tibiae with similar apparent BMD were randomly divided into three groups of ten specimens. Paired tendons were randomly divided into two experimental groups: Group 1 = 8 h incubation/15 min rehydration; Group 2 = 2 h incubation/1 h rehydration. Group 3 (control) consisted of ten standardly prepared tendons with 20 min rehydration. Tissue handling properties were graded during allograft preparation using a modified visual analog scale. Similar diameter allografts were fixed in matched diameter extraction drilled tibial tunnels with 35 mm long, 1 mm > tunnel diameter bioabsorbable interference screws. Potted constructs were mounted in a servo hydraulic device, pretensioned between 10-50 N at 0.1 Hz (10 cycles), and isometric pretensioned at 50 N for 1 min, prior to 500 submaximal loading cycles (50-250 N) at 0.5 Hz, and load to failure testing (20 mm/min). Constructs prepared under extreme conditions generally displayed comparable biomechanical properties to the control condition. Group 1 (8 h incubation/15 min rehydration)(-34 +/- 35 ms) and Group 2 (2 h incubation/1 h rehydration) (-22 +/- 38 ms) displayed smaller mean displacement-load peak phase timing differences over the initial ten cycles compared to Group 3 (control)(-42 +/- 49 ms), P = 0.004, suggesting greater relative construct stiffness. Group 1 (8 h incubation/15 min rehydration) (234.9 +/- 34 N/mm) and Group 2 (2 h incubation/1 h rehydration)(231.3 +/- 43 N/mm) displayed lower construct stiffness during load to failure testing than Group 3 (control)(284.5 +/- 25.2 N/mm), P = 0.003. Group 1 (8 h incubation/15 min rehydration) differed from Group 2 (2 h incubation/1 h rehydration) and Group 3 (control) for perceived tensile stiffness (2.4 +/- 2.0 vs. 7.0 +/- 0.5 and 7.9 +/- 0.3, respectively), compressive resilience (1.7 +/- 0.8 vs. 5.9 +/- 1.0 and 7.8 +/- 0.4, respectively), handling ease (2.8 +/- 1.0 vs. 6.5 +/- 0.5 and 7.0 +/- 0.7, respectively), color (2.6 +/- 0.8 vs. 4.7 +/- 0.7 and 5.1 +/- 0.3, respectively) and texture (4.0 +/- 0.8 vs. 6.2 +/- 0.8 and 6.8 +/- 0.8, respectively) (P < 0.0001). Group 2 (2 h incubation/1 h rehydration)(6.0 +/- 0.7 and 5.9 +/- 1.0, respectively) also differed from Group 3 (control)(6.8 +/- 0.8 and 7.8 +/- 0.4, respectively) for general "feel" and compressive resilience (P < 0.0001). Tensile stiffness and compressive resilience displayed moderate and weak relationships, respectively with displacement during submaximal cyclic loading (r2 = 0.78 and 0.58, respectively), stiffness (r2 = 0.33 and 0.44, respectively) and load at failure (r2 = 0.59 and 0.37, respectively) for Group 3 (control), but not for experimental Group 1 (8 h incubation/15 min rehydration) or Group 2 (2 h incubation/1 h rehydration). Knee surgeons should be aware that soft tissue tendon decellularization and cryopreservation may change the biomechanical stiffness, tissue handling properties, and relationships between these variables compared to standardly prepared allograft tissue.

Effect of cryoprotectant incubation time on handling properties of allogeneic tendons prepared for knee ligament reconstruction

Soft tissue tendon allografts prepared for anterior cruciate ligament reconstruction are becoming increasingly popular; although concerns exist regarding increased long-term laxity and traumatic rupture rates. This qualitative study evaluated the tissue handling properties of human tibialis posterior tendons prepared using a patented process to improve allograft remodeling and ligamentization under differing cryoprotectant incubation times over 60-min rehydration. Tendons that had been incubated for 8 h had smaller diameters than those that were incubated for 2 h (8.5 +/- 1.5 mm vs. 9.1 +/- 1.3 mm, p = 0.02). Qualitative tissue handling property results indicated that the 8-h incubation had a negative affect on tissue color. Both incubation time and rehydration time influenced tensile stiffness, compressive resilience, and ease of tissue handling for allograft preparation with the 8-h group displaying poorer results. This study concludes that an 8-h cryoprotectant incubation time is detrimental to qualitative allogeniec tibialis posterior tendon properties. Both groups tended to improve with longer rehydration times, however the 8-h incubation group remained actively dehydrated as evidenced by its smaller diameter and poorer tissue handling properties. Suboptimally rehydrated tendons would be more likely to accrue damage during allograft preparation or during implantation.