Principles of postoperative anterior cruciate ligament rehabilitation

Postoperative Multimodal Approach to Pain Control in Anterior Cruciate Ligament Autograft Surgery: A Single-Center Series

Background: Anterior cruciate ligament (ACL) injuries are prevalent and represent a significant socioeconomic burden, as ACL injuries account for nearly 60% of all knees joint traumas. The purpose of this study is to emphasize the role of arthroscopic ACL reconstruction and the challenges in postoperative pain management. Methods: This study involved 90 patients undergoing ACL reconstruction, categorized into three groups receiving different pain management protocols. The focus was on evaluating the efficacy of multimodal analgesia using lidocaine and magnesium sulfate. The main outcome was pain assessment using the Visual Analog Scale (VAS). Results: Patients receiving fentanyl, lidocaine, and magnesium sulfate (FLM) reported significantly lower pain scores in the postoperative period. Minimal use of additional opioids was observed, suggesting effective pain management with the multimodal analgesia regimen. Conclusions: The study showed that multimodal analgesia, including FLM, effectively manages postoperative pain following ACL reconstruction. This study showed significantly lower pain scores with FLM, highlighting its potential in early postoperative pain relief. Future research should consider long-term outcomes and cost-effectiveness, emphasizing the need for more comprehensive evaluations of multimodal analgesia’s impact.

Cost-Outcome Descriptive Study for Mobile App (UPSCALER) in the Rehabilitation of Anterior Cruciate Ligament (ACL) Injuries After Reconstructive Surgery

Anterior cruciate ligament (ACL) injuries are a significant concern in athletes, often leading to long-term complications and reduced quality of life. Despite advancements in surgical techniques, outcomes following ACL reconstruction remain suboptimal, largely due to poor adherence to postoperative rehabilitation. This study introduces a novel postoperative rehabilitation approach utilizing a smartphone application, UPSCALER, developed by the Universiti Putra Malaysia Sports Injury and Arthroscopic Surgery Center of Excellence. The application delivers a validated accelerated rehabilitation protocol through instructional videos tailored to each patient's recovery phase. Results from the study demonstrate promising outcomes, including improvements in Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales post-rehabilitation, potentially attributed to increased adherence facilitated by the application's accessibility. Furthermore, the study explores the cost-effectiveness of this approach compared to conventional methods. In conclusion, smartphone application-guided rehabilitation shows promise in improving ACL reconstruction outcomes, warranting further research to validate its effectiveness and long-term impact on patient recovery and healthcare costs.

Nordic hamstring exercises in functional knee rehabilitation after anterior cruciate ligament reconstruction: a prospective, randomised, controlled study

To study the effect of using Nordic hamstring exercise method on muscle strength and knee joint stability of patients after ACL reconstruction. 60 patients admitted to our hospital for ACL reconstruction were randomly divided into a test group (n = 30, applying Nordic hamstring exercise) and a control group (n = 30, applying conventional rehabilitation training methods), and the difference in the circumference of the thighs of the patients in the two groups was analysed after training, and the peak torque (PT), total torque (PT), and flexion and extension strength were measured by using the Biodex system3 Multi-joint Isokinetic Testing System at knee joints with an angular velocity of 60°/s and 120°/s. The peak torque (PT), total work (TW), and average peak torque (AVG PT) were measured by extension and flexion strength at angular velocity, and the Lysholm Knee Score was used to assess the knee function of 60 patients. There was no difference in the difference in thigh circumference between the two groups before surgery (P > 0.05); the difference in thigh circumference between the patients in the test group at 12 and 24 weeks after surgery was (- 0.35 ± 0.22) cm and (0.12 ± 0.03) cm, respectively, which were higher than those in the control group, (- 0.51 ± 0.15) cm and (- 0.41 ± 0.34) cm (P < 0.05). At the 12th and 24th postoperative weeks, the popliteal muscle strength of both groups was improved compared with that before surgery; among them, by comparing the popliteal peak moments with different angular velocities, the ratio of popliteal peak moment on the affected side/peak moment on the healthy side of the popliteal muscle of the experimental group was significantly higher than that of the control group, and the difference was significant (P < 0.05), but there was still a gap compared with that of the healthy side. The Lachmen test and the anterior drawer test were negative in the test and control groups at the 24th postoperative week of review, and the anterior tibial shift was < 5 mm in the KT-1000 test, and the difference in the anterior shift was < 3 mm compared with the healthy side, and there was no significant difference between the two groups. By Nordic hamstring exercise can make patients after knee ACL reconstruction reduce patient pain, accelerate the recovery of knee function, improve the swelling of the lower limb, reach the level of flexor strength of the healthy side within 24 weeks, and can increase the stability of the knee joint.

Clinical, Biomechanical, and Self-reported Health Status After ACL Reconstruction With Meniscal Repair in Soccer Players: Results at Minimum 1-Year Follow-up

BACKGROUND

Performing meniscal repair with anterior cruciate ligament reconstruction (ACLR) has been shown to contribute to the long-term preservation of knee health and gait biomechanics.

PURPOSE

To evaluate the role of meniscal repair in the performance of semiprofessional soccer players who returned to sport after ACLR.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This study included 51 male soccer players (mean ± SD age, 28.82 ± 5.33 years) who underwent ACLR at a single institution between July 2018 and July 2019. The players were divided into 3 groups according to surgery type: ACLR only (n = 30), ACLR with lateral meniscal repair (n = 9), and ACLR with medial meniscal repair (n = 12). Outcomes were evaluated through clinical examination, self-reported health questionnaires (Cincinnati Knee Rating System, Tegner activity score, Tegner Lysholm Knee Scoring Scale, Tampa Scale of Kinesiophobia, and ACL-Return to Sport After Injury), and biomechanical performance evaluations (balance, strength, coordination, and symmetry tests). Parametric and nonparametric tests were carried out for multiple comparisons.

RESULTS

The mean ± SD follow-up time was 20.75 ± 9.38 months. Although no significant differences emerged in clinical and self-reported health status, almost all the physical parameters tested resulted in lower performance in players treated with ACLR and meniscal repair. Moreover, patients with ACLR with lateral meniscal repair reported higher pain and fear of reinjury, with lower outcomes in terms of strength, symmetry, and coordination as compared with the other 2 groups. Balance abilities were significantly affected in players who underwent meniscal repair as compared with those who underwent ACLR only.

CONCLUSION

The findings showed that biomechanical performance measures and fear of reinjury were significantly worse in soccer players with associated meniscal repair at a minimum 1-year follow-up, especially in those with a lateral meniscal tear.

THE COVID-19 PANDEMIC DID NOT AFFECT REHABILITATION FOLLOWING ACL RECONSTRUCTION

ABSTRACT Objective: To assess postoperative rehabilitation patterns in patients who underwent Anterior Cruciate Ligament Reconstruction (ACLR) during the COVID-19 pandemic. Methods: A retrospective study of patients who underwent primary isolated ACLR between February 2019 and July 2020. Two different periods were evaluated. The “COVID group” represents the period from February 1st to July 1st of 2020 and the “non-COVID group” represents the equivalent period in 2019. Rehabilitation features and the effect of the COVID-19 pandemic on rehabilitation habits were assessed. Patient outcome scores were assessed using the Lysholm, Tegner, and International Knee Documentation Committee (IKDC) questionnaires. Subjective satisfaction, post-operative complications, and subsequent surgeries were recorded. Results: The groups did not differ significantly in demographics, functional outcome scores, or subjective satisfaction. There was no significant difference in rehabilitation patterns between the groups. In the COVID group, only one patient (4%) reported participation in online physiotherapy. Conclusions: There were no differences in the post-operative rehabilitation patterns, including duration, length, and environment of the training, between patients who underwent primary isolated ACLR during the COVID-19 pandemic and those who underwent the treatment in the preceding non-COVID year. Patient outcome scores, subjective satisfaction, and subsequent surgery rates did not differ between the groups. Level of evidence IV; Therapeutic studies - investigation of treatment results.

Isometric Knee Strength is Greater in Individuals Who Score Higher on Psychological Readiness to Return to Sport After Primary Anterior Cruciate Ligament Reconstruction

Background

Anterior cruciate ligament (ACL) injury is extremely common among athletes. Rate of second ACL injury due to surgical graft rupture or contralateral limb ACL injury is approximately 15-32%. Psychological readiness to return to sport (RTS) may be an important predictor of successful RTS outcomes. Psychological readiness can be quantified using the ACL Return to Sport after Injury (ACL-RSI) questionnaire, with higher scores demonstrating greater psychological readiness.

Purpose

The purpose of this study was to investigate differences in functional performance and psychological readiness to return to sport among athletes who have undergone primary ACL reconstruction (ACLR).

Study Design

Descriptive cohort study.

Methods

Eighteen athletes who had undergone primary ACLR were tested at time of RTS clearance. The cohort was divided into two groups, high score (HS) and low score (LS), based on median ACL-RSI score, and performance on static and dynamic postural stability testing, lower extremity isokinetic and isometric strength testing, and single leg hop testing was compared between the groups using an independent samples t-test.

Results

The median ACL-RSI score was 74.17. The average ACL-RSI score was 83.1±6.2 for the HS group and 61.8±8.0 for the LS group. High scorers on the ACL-RSI performed significantly better on isometric knee flexion as measured via handheld dynamometry (22.61% ±6.01 vs. 12.12% ±4.88, p=0.001) than the low score group.

Conclusion

The findings suggest that increased knee flexion strength may be important for psychological readiness to RTS after primary ACLR. Further research is indicated to explore this relationship, however, a continued emphasis on improving hamstring strength may be appropriate during rehabilitation following ACLR to positively impact psychological readiness for RTS.

Level of Evidence

III.

Factors Influencing Treatment Outcome and Proprioception after Electrocoagulation of the Femoral Insertion of the Anterior Cruciate Ligament

(1) Background: Studies have established that exercises shaping the sense of deep sensation are an important element of medical rehabilitation of patients after vaporization of the femoral insertion of the anterior cruciate ligament and affect the restoration of correct movement patterns, thus reducing the risk of injuries. The aim of this study was to determine the factors influencing the treatment outcome and deep-feeling function after applying a specific rehabilitation scheme 12 weeks after anterior cruciate ligament electrocoagulation surgery. (2) Methods: The study group consisted of 41 patients after partial rupture of the anterior cruciate ligament, who underwent electrocoagulation of the femoral cruciate ligament attachment and microfracture of the femoral attachment area. All patients were operated on by the same surgeon and then rehabilitated according to the same medical rehabilitation protocol. The anthropometric and clinical data were collected through an anterior drawer test, Lachman test, assessment of the range of movements in the knee joint, muscle strength test, Unterberger test and Lysholm questionnaire. The assessment was performed before the surgery, and then on days 7-10, after 6 and 12 weeks of rehabilitation treatment. (3) Results: Statistical improvement of the parameters was demonstrated by strength of the quadriceps and hamstrings muscle, the Unterberger test, and the Lysholm scale after surgery. A negative correlation was found between the Unterberger test and Lysholm scale at the end of the research period and it differed depending on the gender and the dominant limb. The Lysholm scale and muscle strength were independent of sex, dominant extremity and associated damage of the meniscus and cartilage. The Lysholm scale 6 weeks after surgery negatively correlated with BMI. (4) Conclusions: Stability of the knee joint and improvement of proprioception were demonstrated 12 weeks after treatment with an ACL electrocoagulation and rehabilitation regimen. The factors contributing to a better treatment outcome were greater muscle strength, less thigh asymmetry, better sense of depth, younger age and lower body weight.

Maximizing Recovery in the Postpartum Period: A Timeline for Rehabilitation from Pregnancy through Return to Sport

Increased participation and duration in sport has become commonplace for women with their involvement often including the transition to motherhood in the peak of their athletic careers. No rehabilitation models that assess the full spectrum of pregnancy to postpartum have been developed for women to assist in safe exercise progressions that reduce postpartum symptoms and optimize performance during the return to full activity. Referral to physical therapy both in the prenatal and postnatal period is currently not considered standard of care to reduce prevalence of symptoms such as musculoskeletal pain, diastasis recti, and pelvic floor dysfunction which may ultimately interfere with physical activity and performance. This commentary presents a timeline and suggested progression for exercise participation to improve awareness of the musculoskeletal changes that occur after labor and delivery. The concepts covered may increase the understanding of how to manage pregnant and postpartum athletes from a musculoskeletal perspective and serve as a starting point for establishing appropriate and guided rehabilitation for safe return to sport after childbirth.

Protocolo de reabilitação acelerada precoce versus conservadora retardada após reconstrução do ligamento cruzado anterior: Um ensaio prospectivo randomizado

Objective  To compare the effectiveness of the early accelerated rehabilitation and delayed conservative rehabilitation protocols after arthroscopic anterior cruciate ligament reconstruction, in terms of the International Knee Documentation Committee (IKDC) score, pain (according to the Visual Analog Scale), laxity, and stiffness one year postoperatively to determine the best outcome.

Materials and Methods  A total of 80 subjects were divided into 2e groups (early accelerated group and delayed conservative group), which were analyzed by the Pearson Chi-squared and Wilcoxon rank-sum tests.

Results  One year postoperatively, knee laxity was significantly higher ( p  = 0.039) in the early accelerated group compared with the delayed conservative group. Regarding postoperative pain (according to the Visual Analogue Scale) and IKDC scores, both groups presented similar results. The postoperative range of motion was better in the early accelerated group, but this was not statistically significant ( p  = 0.36).

Conclusion  One year postoperatively, the early accelerated rehabilitation protocol was associated with significant knee laxity compared to the delayed conservative rehabilitation protocol.

Current Standards of Early Rehabilitation after Anterior Cruciate Ligament Reconstruction in German Speaking Countries-Differentiation Based on Tendon Graft and Concomitant Injuries

Background: Although anterior cruciate ligament reconstruction (ACLR) is a well-established procedure and is standardly performed by orthopedic surgeons all over the world, there does not seem to be a standard protocol for early rehabilitation. The purpose of this study was to give answers to the following questions: (i) Does (a) the use of a specific tendon graft, and (b) potentially additional therapy of concomitant pathologies influence surgeons’ choice of a distinct postoperative rehabilitation protocol after ACLR? (ii) To what extent do these rehabilitation recommendations differ? Methods: Retrospective analysis of currently used early rehabilitation protocols after ACLR in German-speaking countries (GER, AUT and SUI) was conducted. Rehabilitation criteria included weight bearing, range of motion (ROM), the utilization of braces, continuous passive/active motion therapy (CPM/CAM), rehabilitation training and sport-specific training. Tendon grafts were differentiated as hamstring (HAM) and bone−patellar tendon−bone grafts (BTB). Concomitant pathologies included meniscus injuries (+M) and unhappy triad injuries (+UTI). Results: Most of the surveyed protocols were differentiated according to the used tendon graft or additional therapy of concomitant injuries (ACLR-differentiated, n = 147 vs. ACLR without graft differentiation, n = 58). When comparing ACLR-HAM and ACLR-BTB, significant differences were found regarding weight bearing (p = 0.01), ROM (p = 0.05) and the utilization of braces (p = 0.03). Regarding ACLR+M, an overall significant decelerated rehabilitation could be detected. After ACLR+UTI-therapy, a significant delayed start to full weight bearing (p = 0.002) and ROM (p < 0.001) was found. Conclusions: Most orthopedic surgeons from German-speaking countries differentiate early rehabilitation after ACLR according to the tendon graft used and therapy of concomitant pathologies. No consensus about early rehabilitation after ACLR is available. However, tendencies for an accelerated rehabilitation after ACLR-BTB and a more restrained rehabilitation of multiple injured knees were detected.

THE EFFECTS OF NEUROMUSCULAR ELECTRICAL STIMULATION IN ASSOCIATION WITH WHEY PROTEIN SUPPLEMENTATION AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

OBJECTIVE

To analyze the effects of neuromuscular electrical stimulation of the femoral quadriceps associated or not with whey protein supplementation on the electromyographic activity and body mass distribution in volunteers undergoing anterior cruciate ligament reconstruction.

METHODS

24 volunteers were randomly divided into three groups: basal control, whey protein in association with neuromuscular electrical stimulation, and neuromuscular electrical stimulation alone.

RESULTS

In the postoperative evaluation, during the mini squat, the basal group showed a decrease in the electromyographic activity of the vastus medialis (p = 0.005, eyes open; p = 0.003, eyes closed), vastus lateralis (p = 0.005, eyes open; p = 0.020; eyes closed) and rectus femoris (p = 0.075, eyes open; p = 0.074, eyes closed) and of body mass distribution in the injured limb (p < 0.001, eyes open; p < 0.001, eyes closed), and in the healthy limb (p < 0.001, eyes open; p < 0.001, eyes closed).

CONCLUSION

The early use of neuromuscular electrical stimulation of the quadriceps femoris maintained the electromyographic activity of the vastus medialis and vastus lateralis muscles and prevented asymmetries in body mass distribution 15 days after anterior cruciate ligament reconstruction. Level of Evidence I, High quality randomized trial.

The use of an alternating magnetic field in the resorption of postoperative joint effusion following anterior cruciate ligament reconstruction: A randomized double-blind controlled trial

CONTEXT

There are no scientific reports unambiguously describing the efficacy of alternating magnetic field therapy in patients after anterior cruciate ligament (ACL) reconstruction in the early postoperative period.

OBJECTIVE

This study aims to evaluate the efficacy of using an alternating magnetic field in the resorption of postoperative joint effusion in patients after ACL reconstruction.

STUDY DESIGN

A randomized, double-blind placebo-controlled study.

SETTING

Inpatients.

PARTICIPANTS

Forty patients were enrolled in the trial. However, the final study group consisted of 38 patients (28 men and 10 women) after ACL reconstruction who were randomly divided into an experimental group (19 patients) and a control group (19 patients).

INTERVENTION

Each group received magnetic field therapy in the postoperative period, but only 1 apparatus emitted a magnetic field (the experimental group). Patients used the apparatus every day for 30 minutes for the next 11 days. The parameters in both devices were the same-3 mT and 10 Hz.

MAIN OUTCOME MEASURES

The measurement of the knee circumference and range of motion were made. The knee circumference measurement was performed before magnetic field therapy began and for 11 days after magnetic field treatment. The active knee range of motion was evaluated before and after magnetic field therapy was completed.

RESULTS

There were no statistically significant differences between the groups in the reduction of post-operative joint effusion or knee joint function.

CONCLUSION

In patients after ACL reconstruction, in whom an alternating magnetic field was used to treat postoperative joint effusion, there were no beneficial effects on the analyzed variables compared to the control group.

The importance of biomechanical assessment after Return to Play in athletes with ACL-Reconstruction

BACKGROUND

Barriers to successful return to previous level of activity following Anterior Cruciate Ligament Reconstruction (ACLR) are multifactorial and recent research suggests that athletic performance deficits persist after completion of the rehabilitation course in a large percentage of patients.

RESEARCH QUESTION

Do technology-based biomechanical assessments reveal underneath differences in both recreational and competitive athletes in Return to Play after ACL-Reconstruction?

METHODS

Thirty soccer athletes (26.9 ± 5.7 years old, male) with ACL injury were surgically treated with all-inside technique and semitendinosus tendon autograft. Before 2 years from surgery, they were called back for clinical examination, self-reported psychological scores, and biomechanical outcomes (balance, strength, agility and velocity, and symmetry). Athletes were classified into recreational (n = 15) and competitive (n = 15) according to the self-reported Return to Play Level based on the TALS post-injury. Nonparametric statistical tests have been adopted for group comparisons in terms of age, concomitant presence of meniscus tear, injury on dominant leg, presence of knee laxity, presence of varus/valgus, body sides, and return to different levels of sports.

RESULTS

Competitive athletes showed better in terms of strength (45.3 ± 5.4 W kg-1 vs 39.3 ± 3.4 W kg-1, P ≤ 0.01) associated with good self-reported outcomes (TLKS, CRSQ) and low fear of reinjury (TSK). However, all the athletes had a functional deficit in at least one subtest, and a safe return to sports could not have been recommended. Our findings confirmed that demographics, physical function, and psychological factors were related to playing the preinjury level sport at mean 2 years after surgery, supporting the notion that returning to sport after surgery is multifactorial.

SIGNIFICANCE

A strict qualitative and quantitative assessment of athletes' status should be performed at different follow-ups after surgery to guarantee a safe and controlled RTP.

Single leg aerobic capacity and strength in individuals with surgically repaired anterior cruciate ligaments

OBJECTIVES

Compare single-leg aerobic capacity and strength differences between the surgically repaired ACL leg (injured) and the uninjured leg.

DESIGN

Cross-sectional study.

SETTING

Laboratory.

PARTICIPANTS

Eight participants (5 female, 3 male, age = 23 ± 3.5 y, mass = 72.3 ± 17.3 kg, height = 169.7 ± 9.4 cm) that returned to play from ACL surgery between six and 18 months.

MAIN OUTCOME MEASURES

Participants performed an aerobically-based, single-leg cycling protocol to determine maximum oxygen consumption, ventilatory threshold, heart rate, rating of perceived exertion, and maximal watts cycled. Participants also performed isokinetic knee flexion and extension on a dynamometer to assess peak torque, total work, work fatigue, and power.

RESULTS

There were no statistical differences in single-leg aerobic capacity or strength outcomes between the injured and uninjured legs.

CONCLUSIONS

Individuals who have had an ACL surgically repaired six to 18 months after return to play do not appear to have aerobic capacity or strength deficits between the injured leg and uninjured leg.

Analgesic efficacy of a single-dose, intraoperative, intra-articular morphine application in ACL reconstruction

Background

Anterior cruciate ligament (ACL) reconstruction is the mainstay treatment for the symptomatic anterior cruciate ligament insufficiency. Postoperative rehabilitation is the key main factor in successful surgical outcome but, the postoperative pain is a major obstacle to achieve good postoperative rehabilitation. The purpose of this study is to compare the effects of intra-articular morphine (IAMO) with normal saline [control group (C)] for postoperative pain control in the ACL reconstruction knees.

Methods

Patients who underwent ACL reconstruction during 2017-2019 were included, prospectively, from Khon Kaen hospital and randomized into 2 groups: IAMO group and the control group (C). After surgery, all patients received the same rehabilitation protocols. The results were assessed using the visual analogue scale (VAS), following the spinal block anesthesia at 6, 12,18 and 24 hours. Time to first analgesic request, range of motion and adverse effects were recorded.

Results

Forty patients were included and twenty were designated to the IAMO group. The mean age was 25.3±7.6 years and 80 percent of the patients were males. The IAMO group had lower VAS scores at the 12 and 24 hour postoperative periods [greatest variance at 12 hours (4.7±1.7 vs 5.8±1.6)]. In the IAMO group, time to first analgesic request was longer and morphine consumption was less, but these were not statistically significant. No complications were observed in both groups.

Conclusions

The trend of VAS in the IAMO group was lower than in the control group, especially at 12 hours after surgery with no statistically significant differences. From this study and with the advantages of IAMO after ACL reconstruction, IAMO is useful in ACL reconstruction patients without complications.

Isokinetic eccentric training is more effective than constant load eccentric training for quadriceps rehabilitation following anterior cruciate ligament reconstruction: a randomized controlled trial

OBJECTIVE

To compare the effects of conventional (constant load) eccentric training and isokinetic eccentric training on quadriceps muscle mass, strength and functional performance in recreational athletes following anterior cruciate ligament (ACL) reconstruction.

METHODS

Thirty recreational male athletes (25 years old) undergoing ACL reconstruction received a standard rehabilitation program. Volunteers were randomized to conventional group (CG; n = 15) or isokinetic group (IG; n = 15) to be engaged in a 6-week (2 sessions/week) quadriceps eccentric training program at the extensor chair or at the isokinetic dynamometer, respectively. Assessments of quadriceps muscle mass (through magnetic resonance imaging), strength (through isokinetic dynamometry) and self-aware functionality (through questionnaire) were performed before and after the training programs. Single leg hop test performance was assessed only at post-training evaluation.

RESULTS

IG had significantly higher improvements than CG (p < 0.05) for all muscle mass outcomes (+17-23% vs. +5-9%), as well as for isometric (+34% vs. +20%) and eccentric (+85% vs. +23%) peak torques. There was no between-group difference (p > 0.05) for concentric peak torque, Lysholm score, and single leg hop test.

CONCLUSION

Isokinetic eccentric training promotes greater responses than conventional eccentric training on quadriceps muscle mass and strength of recreational athletes following ACL reconstruction.

Knee Extensors Muscle Plasticity Over a 5-Years Rehabilitation Process After Open Knee Surgery

We investigated molecular and cellular parameters which set metabolic and mechanical functioning of knee extensor muscles in the operated and contralateral control leg of 9 patients with a chronically insufficient anterior cruciate ligament (ACL; 26.6 ± 8.3 years, 8 males, 1 female) after open reconstructive surgery (week 0), after ambulant physiotherapy under cast immobilization (week 9), succeeding rehabilitation training (up to week 26), and subsequent voluntary physical activity (week 260). Clinical indices of knee function in the operated leg were improved at 52 weeks and remained at a comparable level at week 260. CSA of the quadriceps (-18%), MCSA of muscle fibers (-24%), and capillary-to-fiber ratio (-24%) in m. vastus lateralis from the ACL insufficient leg were lower at week 0 than reference values in the contralateral leg at week 260. Slow type fiber percentage (-35%) and mitochondrial volume density (-39%) were reduced in m. vastus lateralis from the operated leg at weeks 9 and 26. Composition alterations in the operated leg exceeded those in the contralateral leg and, with the exception of the volume density of subsarcolemmal mitochondria, returned to the reference levels at week 260. Leg-specific deterioration of metabolic characteristics in the vasti from the operated leg was reflected by the down-regulation of mitochondrial respiration complex I-III markers (-41-57%) at week 9. After rehabilitation training at week 26, the specific Y397 phosphorylation of focal adhesion kinase (FAK), which is a proxy for mechano-regulation, was elevated by 71% in the operated leg but not in the contralateral leg, which had performed strengthening type exercise during ambulant physiotherapy. Total FAK protein and Y397 phosphorylation levels were lowered in both legs at week 26 resulting in positive correlations with mitochondrial volume densities and mitochondrial protein levels. The findings emphasize that a loss of mechanical and metabolic characteristics in knee extensor muscle remains detectable years after untreated ACL rupture, which may be aggravated in the post-operative phase by the deterioration of slow-oxidative characteristics after reconstruction due to insufficient load-bearing muscle activity. The reestablishment of muscle composition subsequent to years of voluntary physical activity reinforces that slow-to-fast fiber transformation is reversible in humans.

Strength and functional symmetry is associated with post-operative rehabilitation in patients following anterior cruciate ligament reconstruction

PURPOSE

To investigate strength and functional symmetry during common tests in patients after anterior cruciate ligament reconstruction (ACLR), and its association with post-operative rehabilitation.

METHODS

At a median 11.0 months post-surgery (range 10-14), 111 ACLR patients were assessed. A rehabilitation grading tool was employed to evaluate the duration and supervision of rehabilitation, as well as whether structured jumping, landing and agility exercises were undertaken. Patients completed the Noyes Activity Score (NSARS), maximal isokinetic knee extensor and flexor strength assessment, and a 4-hop test battery. Limb Symmetry Indices (LSIs) were calculated, presented for the entire group and also stratified by activity level. ANOVA evaluated differences between the operated and unaffected limbs across all tests. Correlations were undertaken to assess the relationship between post-operative rehabilitation and objective test LSIs.

RESULTS

The unaffected limb was significantly better (p < 0.0001) than the operated limb for all tests. Only 52-61 patients (47-55%) demonstrated LSIs ≥ 90% for each of the hop tests. Only 34 (30.6%) and 61 (55.0%) patients were ≥ 90% LSI for peak quadriceps and hamstring strength, respectively. Specifically in patients actively participating in jumping, pivoting, cutting, twisting and/or turning sports, 21 patients (36.8%) still demonstrated an LSI < 90% for the single hop for distance, with 37 patients (65.0%) at < 90% for peak knee extension strength. Rehabilitation was significantly associated with the LSIs for all tests.

CONCLUSION

Rehabilitation was significantly correlated with limb symmetry, and lower limb symmetry was below recommended criterion for many community-level ACLR patients, including those already engaging in riskier activities. It is clear that many patients are not undertaking the rehabilitation required to address post-operative strength and functional deficits, and are being cleared to return to sport (or are returning on their own accord) without appropriate evaluation and further guidance.

LEVEL OF EVIDENCE

IV.

Two-Plane Assessment of Knee Muscles Isometric and Isokinetic Torques After Anterior Cruciate Ligament Reconstruction

Background

We tested the hypothesis that, in patients participating in 17 weeks of postoperative physiotherapy after anterior cruciate ligament reconstruction (ACLR), maximal isometric torque (IT) and peak torque (PT) generated by the muscles affecting the operated knee joint in the sagittal and transverse planes are not restored. We also present the application of IT and PT measurements of the muscles affecting the knee joint in 2 planes of motion.

Material/Methods

IT and PT of the knee extensor and flexor muscles and the muscles internally rotating the shin were measured in 30 males who participated in postoperative physiotherapy for 17 weeks after ACLR (ACLR group) and 30 males with no injuries (control group).

Results

Significantly lower IT and PT values were noted in the operated knee extensors and flexors. The differences were also noted in the PT for the muscles internally rotating the shin and in the IT of those muscles in the position of 25° of internal rotation. Significantly lower relative IT and PT values were noted for studied muscle groups in comparison to the control group.

Conclusions

Seventeen weeks of postoperative physiotherapy after ACLR did not result in complete restoration of IT and PT of the muscles affecting the operated knee joint, suggesting that even after 17 weeks of physiotherapy following ACLR, athletes may not be ready to return to sports. The results demonstrate the usefulness of biplanar analysis of muscle strength under isometric and isokinetic conditions in the monitoring and assessment of physiotherapeutic procedures.

The Timing of Rehabilitation Commencement After Reconstruction of the Anterior Cruciate Ligament

One of the most common injuries of the knee joint is a rupture of the anterior cruciate ligament (ACL). Most authors believe that early rehabilitation of patients after ACL reconstruction promotes better treatment outcomes. Less is known about the influence of the time that passes from injury to surgical reconstruction. Therefore, the goal of this study was to assess the dependence of treatment outcomes of ACL on injury-to-reconstruction and reconstruction-to-rehabilitation time lags. The study included 30 patients of the mean age 34 ± 7 years with trauma-related rupture of ACL and its surgical reconstruction. The time range from ligament rupture to its reconstruction was 120-180 days and from reconstruction to rehabilitation was 1-120 days. Postsurgical rehabilitation outcomes were assessed with the Lysholm knee scale and the IKDC 2000 subjective knee evaluation form. The scales were applied before and after rehabilitation. We found distinct improvements in all physical symptoms in the damaged knee joint, regardless of the time elapsed from trauma to ACL reconstruction and from ACL reconstruction to rehabilitation. The beneficial outcomes of rehabilitation were significantly inversely associated with the time elapsing from reconstruction to rehabilitation commencement but failed to depend on the time from ACL rupture to reconstruction. We conclude that rehabilitation should start as early as possible after ACL reconstruction to optimize the beneficial outcomes in terms of functional physical recovery, whereas the injury-to-reconstruction delay is less meaningful to this end.

Electromyographic activity of selected trunk, core, and thigh muscles in commonly used exercises for ACL rehabilitation

[Purpose] Most of rehabilitation programmes for Anterior Cruciate Ligament (ACL) injury focus on quadriceps-hamstrings activation imbalances and less is known about kinetically linked muscles. This study investigated electromyographic activity of selected trunk, core, and thigh muscles during common rehabilitation exercises for ACL injury. [Subjects and Methods] Twelve active female volunteers participated in this cross-sectional laboratory study. Surface EMG was used to compare activation of eight trunk, hip/core, and lower limb muscles: Erector Spinae (ES), Rectus Abdominis (RA), Gluteus Maximus (GM), Vastus Lateralis (VL), Rectus Femoris (RF), Vastus Medialis (VM), Biceps Femoris (BF), and Semitendinosus (ST) during Forward Lunge, Double Leg Raise, Glute Bridge, Sit-Up, and Squat. [Results] Forward lunge produced significantly higher activation in the VM (61.1 ± 19.4), VL (59.2 ± 12.9), and RF (32.0 ± 2.6). Double leg raise generated highest activity in the RF (26.6 ± 2.8) and RA (43.3 ± 4.4); and Glute Bridge in the GM (44.5 ± 19.0) and BF (22.4 ± 4.3). Sit-up produced the highest activation in the RF (36.6 ± 4.7) followed by RA (18.9 ± 3.8). Squat produced a higher activation in VL (55.0 ± 12.9), VM (51.5 ± 18.2), and ES (40.4 ± 18.3). [Conclusion] This study provide further evidence for developing training programmes for ACL injury prevention and rehabilitation. A combination of exercises to reinstate quadriceps-hamstrings activation balance and enhance core stability is recommended.

Factors Affecting Subjective and Objective Outcomes and Return to Play in Anterior Cruciate Ligament Reconstruction: A Retrospective Cohort Study

Purpose  To analyze the prognostic factors influencing subjective and objective outcomes and return to play (RTP) after anterior cruciate ligament reconstruction (ACL-R).

Methods  Primary ACL-Rs using a transtibial technique performed between 2008 and 2012 were included. Data regarding patients, surgery, sports, and rehabilitation, including an on-field rehabilitation (OFR) and duration of the rehabilitation program, were collected. The International Knee Documentation Committee (IKDC) subjective and objective evaluation forms, and the Knee Injury and Osteoarthritis Outcome Score and Lysholm questionnaires were used for the assessment of subjective and objective outcomes. The Subjective Patient Outcome for Return to Sports and ACL–return to sport after injury (RSI) scores were used for RTP evaluation. Several potential predictors of outcome were tested with a univariate analysis. All the variables with p  < 0.1 were retested in a logistic regression model to evaluate their association with the outcomes.

Results  In total, 176 cases were included with an average follow-up of 44.1 months. Of the patients, 92.2% were rated as normal or nearly normal at the IKDC evaluation. In addition, 90.1% of the patients returned to sport, with 57.6% returning to the same preinjury level. Objective outcomes were negatively influenced by late rehabilitation (odds ratio [OR] = 2.75). Performing an OFR phase during the rehabilitation was associated with better subjective outcomes (OR = 2.71). Length of rehabilitation strongly influenced the RTP rate (OR = 13.16). Conversely, higher ACL-RSI score was inversely related to RTP. Objective IKDC score was inversely related to the ACL-RSI (OR = 0.31), whereas subjective score was correlated with both the total ACL-RSI score (OR = 0.15) and the level of activity (OR = 0.20).

Conclusion  This study confirmed the role of rehabilitation on subjective and objective outcomes and on RTP. Particularly, the complete adherence to a rehabilitation program, including an OFR phase, resulted in better subjective outcomes and higher RTP rate. The relationship between psychological factors, measured through the ACL-RSI score, and RTP was confirmed.

Level of Evidence  Level III, observational study without a control group.

Comparison of Clinical Results, Second-Look Arthroscopic Findings, and MRI Findings Between the Transportal and Outside-In Techniques for Double-Bundle Anatomic Anterior Cruciate Ligament Reconstruction: A Prospective, Randomized Controlled Trial With a Minimum 2-Year Follow-up

BACKGROUND

Although image analysis has shown that the outside-in (OI) technique is associated with different femoral tunnel geometry than the transportal (TP) technique in anatomic anterior cruciate ligament (ACL) reconstruction, it is not known whether clinical results differ between the 2 techniques.

PURPOSE

To compare clinical results, second-look arthroscopic findings, and magnetic resonance imaging (MRI) findings between the TP and OI techniques in anatomic double-bundle (DB) ACL reconstruction.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

From November 2010 to March 2013, 128 patients were enrolled in this study and were randomly assigned to either the TP group (64 patients) or the OI group (64 patients), and DB ACL reconstructions were performed. At the minimum 2-year follow-up (34.9 ± 10.9 months), 111 patients (86.7%) were evaluated with multiple clinical scores and stability tests (KT-2000 arthrometer, Lachman test, and pivot-shift test). Ninety-three knees were evaluated for graft continuity, graft tension, and synovialization by use of second-look arthroscopy. Seventy-eight knees were evaluated on MRI for graft continuity, femoral graft tunnel healing, and graft signal/noise quotient (SNQ). The primary outcome was KT-2000 arthrometer results. Results were compared between the TP and OI groups.

RESULTS

No significant differences were found between the 2 groups in terms of KT-2000 arthrometer results, which was the primary outcome, and other clinical results, with the exception of the postoperative functional test of International Knee Documentation Committee (IKDC) objective score. The ratio of grade A and B on the postoperative functional test of IKDC objective score was significantly larger for the OI group (51/58) than the TP group (36/53) ( P = .005). The second-look arthroscopic findings were not significantly different between the 2 groups in either bundle ( P > .05). In addition, MRI findings did not differ significantly between the 2 groups ( P > .05).

CONCLUSION

With the exception of the functional test of IKDC objective score, we found that clinical results, second-look arthroscopic findings, and MRI findings did not differ significantly between the OI and TP techniques for anatomic ACL reconstruction, although femoral tunnel geometries differed significantly between the 2 techniques.

Neuromuscular electrical stimulation is effective in strengthening the quadriceps muscle after anterior cruciate ligament surgery

PURPOSE

Reduced ability to contract the quadriceps muscles is often found immediately following anterior cruciate ligament (ACL) surgery. This can lead to muscle atrophy and decreased function. Application of neuromuscular electrical stimulation (NMES) may be a useful adjunct intervention to ameliorate these deficits following ACL surgery. The purpose of this review was to determine whether NMES in addition to standard physical therapy is superior to standard physical therapy alone in improving quadriceps strength or physical function following ACL surgery.

METHODS

A computer-assisted literature search was conducted utilizing PubMed, CINAHL, PEDro and Cochrane Library databases for randomized clinical trials where patients after ACL surgery received NMES with the outcome of muscle strength and/or physical function. Random effect models were used to pool summary estimates using standardized mean differences (SMD) for strength outcomes. Physical function outcomes were assessed qualitatively. Methodological quality was assessed from the Physiotherapy Evidence Database (PEDro)-score.

RESULTS

Eleven studies met our inclusion criteria; results from six of these were pooled in the meta-analysis showing a statistically significant short-term effect of NMES (4-12 weeks) after surgery compared to standard physical therapy [SMD = 0.73 (95% CI 0.29, 1.16)]. Physical function also improved significantly more in the NMES groups. PEDro scores ranged from 3/10 to 7/10 points.

CONCLUSION

NMES in addition to standard physical therapy appears to significantly improve quadriceps strength and physical function in the early post-operative period compared to standard physical therapy alone.

LEVEL OF EVIDENCE

I.

Taxonomy for the Rehabilitation of Knee Conditions (TRAK), a Digital Intervention to Support the Self-Care Components of Anterior Cruciate Ligament Rehabilitation: Protocol of a Feasibility Study

BACKGROUND

Rupture of the anterior cruciate ligament (ACL) is common, especially in the active population. In defining the problem of ACL rehabilitation, this study draws from the knowledge that improved self-care, strength, and fitness are associated with better outcomes. Traditional rehabilitation involves regular physiotherapy, but it is not clear what the optimal way for delivering rehabilitation is, and it varies widely across the world. Evidence for treatments are discussed in the literature, however standard length of rehabilitation and frequency of appointments are unknown. Additionally, current rehabilitation models in the National Health Service (NHS) struggle with catering to large volumes of patients and the lengthy time span over which rehabilitation is delivered. The use of eHealth (the Internet in health care) has been successful at delivering behavior change to a number of diverse patient groups. In physiotherapy, problems such as exercise compliance, exercise technique, and managing a broad program of rehabilitation and advice can be challenging. An eHealth intervention called Taxonomy for the Rehabilitation of Knee Conditions (TRAK) to support self-management and behavior change has been developed by patients and clinicians, and acceptability studies have yielded positive results. TRAK is not an exercise rehabilitation protocol; it is a tool to support ACL rehabilitation with personalized plans, prompts, and logs to help adherence and videos and instructions to improve quality and address queries. The patients have their own log-ins and can email their physiotherapist through the website. This novel platform is directly in line with current NHS England, National Institute for Health and Care Excellence, and NHS Improvement agendas that call for rehabilitation initiatives using both technology and supported self-management for patients. This study forms part of a research platform to identify a best practice model of ACL care from the literature and opinions of key stakeholders. Patients' exercise programs and duration of treatment are still based on individual needs, but use of the website may offer improved self-management and function and reduced health resource use.

OBJECTIVE

This is a feasibility study to establish recruitment, retention, sample size estimates, and practicality of collecting outcome measures to inform a future trial comparing the TRAK intervention, which has been rigorously designed to address the challenges of ACL rehabilitation, to usual care.

METHODS

This is a feasibility study comparing 2 groups: standard care and standard care plus eHealth. It will use convergent parallel mixed methods where both qualitative and quantitative data are sought for a more thorough understanding of the objectives. Primary outcomes relate to feasibility, including recruitment, retention, and usage. Secondary outcomes relate to health resource use and patient-rated outcome measures.

RESULTS

This research expects to establish the feasibility of a full-scale randomized controlled trial to explore whether patients who use an eHealth intervention to support ACL rehabilitation have better outcomes plus improved self-efficacy and reduced health resource use than a usual care group.

CONCLUSIONS

The study will provide essential information to support the development and powering of a future clinical trial of eHealth and physiotherapy for patients with ACL reconstruction in the NHS.

Immediate post-operative pain in anterior cruciate ligament reconstruction surgery with bone patellar tendon bone graft versus hamstring graft

Background

Pain in the immediate post-operative period after anterior cruciate ligament (ACL) surgery, apart from an unpleasant experience for the patient, can act as a barrier for static quadriceps contractions and optimum execution of the initial rehabilitation protocol resulting in slow recovery and a later return to full function for a sportsperson. There is no report in the literature comparing pain in the immediate post-operative period after using the two most widely used autografts, bone patellar tendon bone (BPTB) graft and hamstring graft.

Methods

The present study compared the visual analogue scale (VAS) pain score in the immediate post-operative period after arthroscopic ACL reconstruction with the BPTB and hamstring autografts. Both groups consisted of 50 patients each. The mean age of the BPTB and hamstring cohorts was 26.9 ± 7.3 years (age range 18–59 years) and 26.7 ± 9.0 years (age range 17–52 years), respectively. Unpaired t test was applied to compare pain scores between the BPTB and hamstring cohorts.

Results

In the present study, patients in the BPTB cohort showed higher mean pain scores across all the post-operative time intervals except at 6 h. However, the difference in the mean VAS pain score at post-operative 6, 12,18, 24, 36 and 48 h in the two groups was statistically not significant (p value of 1, 0.665, 0.798, 0.377, 0.651 and 0.215 at 6, 12, 18, 24, 36 and 48 h, respectively).

Conclusions

Our study concludes that the arthroscopic ACL reconstruction with BPTB autograft and hamstring autograft is associated with similar pain in the immediate post-operative period. As a result, aggressive physiotherapy regime is not affected by the type of graft being used for ACL reconstruction, as the pain scores in the immediate post-operative period are similar for both techniques.

Trial registration

Clinical Trials Registry-India, CTRI/2016/01/006502

The Degree of Knee Extension Does Not Affect Postoperative Stability or Subsequent Graft Tear Rate After Anterior Cruciate Ligament Reconstruction With Patellar Tendon Autograft

BACKGROUND

There is concern that high degrees of hyperextension may lead to an increase in graft laxity or graft failure after anterior cruciate ligament (ACL) reconstruction.

HYPOTHESIS

Patients with a high degree of hyperextension will have a higher rate of graft tear/failure and lower subjective scores after surgery compared with patients with less knee extension.

STUDY DESIGN

Cohort study, Level of evidence, 2.

METHODS

Of 2329 patients who underwent ACL reconstruction with patellar tendon autograft between 1998 and 2008, there were 625 patients who met the inclusion criteria of having primary ACL surgery, no bilateral ACL injuries, no existing osteoarthritis, and having either ≥6° of knee hyperextension before and after surgery (group A: n = 318; mean hyperextension, 8° ± 2° [range, 6°-15°]) or ≤3° of knee hyperextension before and after surgery (group B: n = 307; mean hyperextension, 0° ± 3° [range, 3° hyperextension to -4° short of 0° neutral]). KT-1000 arthrometer manual maximum difference between knees, range of motion measurements, and subjective follow-up with International Knee Documentation Committee (IKDC) and Cincinnati Knee Ratings Scale (CKRS) surveys were used to evaluate results. Subsequent graft tear related to specific injury within 5 years of surgery was recorded. Graft failure was defined as a KT-1000 manual maximum difference of >5 mm.

RESULTS

Follow-up was obtained from 278 (87%) in group A and 275 (90%) in group B at a mean of 4.1 ± 1.1 years after surgery. The KT-1000 arthrometer manual maximum difference between knees was 2.0 ± 1.4 in group A and 2.1 ± 1.6 in group B (P = .701). Subsequent ACL graft tear/failure occurred in 22 patients (6.9%) in group A and 30 patients (9.8%) in group B (P = .246). Further subanalysis showed that the graft tear/failure rate was 6 of 81 (7.4%) for patients with ≥10° of hyperextension versus 16 of 237 (6.8%) for patients with 6° to 9° of hyperextension. There was no difference in IKDC or CKRS scores between groups after surgery (P = .933 and .155, respectively).

CONCLUSION

Obtaining full hyperextension that is anatomically normal for most patients does not affect objective stability, ACL graft tear/failure rates, or subjective scores after ACL reconstruction with patellar tendon autograft.

Returning to sport after anterior cruciate ligament reconstruction in amateur sports men: a retrospective study

BACKGROUND

According to the literature, 95% of professional athletes return to their sport after anterior cruciate ligament (ACL) reconstruction surgery. The main objective of this study was to verify the return to sport after ACL reconstruction in a homogenous group of amateur sportsmen and sportswomen in a series of Italian patients.

MATERIALS AND METHODS

We designed a retrospective study in which we analyzed the amateur sports patients operated for ACL reconstruction. We verified whether they had returned to sporting activities by comparing the pre- and post-operative Tegner activity scores. We then analyzed the average time to restart the sporting activity and the Lysholm and International Knee Documenting Committee (IKDC) scores.

RESULTS

We analyzed 80 subjects: 47.5% restarted a sports activity, on average after eight months, with a significant reduction of their competitive level or physical commitment, as expressed by the Tegner activity score (pre-operative: 6.9; post-operative: 3.9; p<0.01). The functional knee recovery was good, as expressed by the average score of the Lyshom Knee Scoring Scale (93.5) and the IKDC (74.7).

CONCLUSIONS

In the literature, a return to sport for international case studies and amateur sports is higher than our data. In our population we found the lack of information provided by the medical staff at discharge and follow-up. The assessment at a short-term follow up allowed us to verify that at the end of the post-surgical rehabilitation program the patients were uninformed about the timing and the ability to resume a sporting activity. An efficacious relationship between orthopedic doctor, physiotherapist and a doctor in motorial science may ensure proper treatment the patient after ACL reconstruction. It is important to guarantee the restarting of the sports activity to have a better quality of life in amateur sports. Level of evidence: V.

Current Trends in Anterior Cruciate Ligament Reconstruction: A Review

Anterior cruciate ligament reconstruction (ACLR) is an accepted and established surgical technique for anterior cruciate ligament (ACL) injuries and is now being practiced across the globe in increasing numbers. Although most patients get good to excellent results in the short-term after ACLR, its consequences in the long-term in prevention or acceleration of knee osteoarthritis (OA) are not yet well-defined. Still, there are many debatable issues related to ACLR, such as the appropriate timing of surgery, graft selection, fixation methods of the graft, operative techniques, rehabilitation after surgery, and healing augmentation techniques. Most surgeons prefer not to wait long after an ACL injury to do an ACLR, as delayed reconstruction is associated with secondary damages to the intra- and periarticular structures of the knee. Autografts are the preferred choice of graft in primary ACLR, and hamstring tendons are the most popular amongst surgeons. Single bundle ACLR is being practiced by the majority, but double bundle ACLR is getting popular due to its theoretical advantage of providing more anatomical reconstruction. A preferred construct is the interference fixation (Bio-screw) at the tibial site and the suspensory method of fixation at the femoral site. In a single bundle hamstring graft, a transportal approach for creating a femoral tunnel has recently become more popular than the trans-tibial technique. Various healing augmentation techniques, including the platelet rich plasma (PRP), have been tried after ACLR, but there is still no conclusive proof of their efficacy. Accelerated rehabilitation is seemingly more accepted immediately after ACLR.

Mesenchymal stem cells and collagen patches for anterior cruciate ligament repair

AIM: To investigate collagen patches seeded with mesenchymal stem cells (MSCs) and/or tenocytes (TCs) with regards to their suitability for anterior cruciate ligament (ACL) repair.

METHODS: Dynamic intraligamentary stabilization utilizes a dynamic screw system to keep ACL remnants in place and promote biological healing, supplemented by collagen patches. How these scaffolds interact with cells and what type of benefit they provide has not yet been investigated in detail. Primary ACL-derived TCs and human bone marrow derived MSCs were seeded onto two different types of 3D collagen scaffolds, Chondro-Gide^® (CG) and Novocart^® (NC). Cells were seeded onto the scaffolds and cultured for 7 d either as a pure populations or as “premix” containing a 1:1 ratio of TCs to MSCs. Additionally, as controls, cells were seeded in monolayers and in co-cultures on both sides of porous high-density membrane inserts (0.4 μm). We analyzed the patches by real time polymerase chain reaction, glycosaminoglycan (GAG), DNA and hydroxy-proline (HYP) content. To determine cell spreading and adherence in the scaffolds microscopic imaging techniques, i.e., confocal laser scanning microscopy (cLSM) and scanning electron microscopy (SEM), were applied.

RESULTS: CLSM and SEM imaging analysis confirmed cell adherence onto scaffolds. The metabolic cell activity revealed that patches promote adherence and proliferation of cells. The most dramatic increase in absolute metabolic cell activity was measured for CG samples seeded with tenocytes or a 1:1 cell premix. Analysis of DNA content and cLSM imaging also indicated MSCs were not proliferating as nicely as tenocytes on CG. The HYP to GAG ratio significantly changed for the premix group, resulting from a slightly lower GAG content, demonstrating that the cells are modifying the underlying matrix. Real-time quantitative polymerase chain reaction data indicated that MSCs showed a trend of differentiation towards a more tenogenic-like phenotype after 7 d.

CONCLUSION: CG and NC are both cyto-compatible with primary MSCs and TCs; TCs seemed to perform better on these collagen patches than MSCs.