Basic science of anterior cruciate ligament injury and repair

Acute Anterior Cruciate Ligament Rupture: Repair or Reconstruction? Two-Year Results of a Randomized Controlled Clinical Trial

BACKGROUND

Contemporary anterior cruciate ligament (ACL) suture repair techniques have been subject to renewed interest in recent years. Although several clinical studies have yielded good short-term results, high-quality evidence is lacking in regard to the effectiveness of this treatment compared with ACL reconstruction.

HYPOTHESIS

Dynamic augmented ACL suture repair is at least as effective as anatomic single-bundle ACL reconstruction for the treatment of acute ACL rupture in terms of patient self-reported outcomes at 2 years postoperatively.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

After stratification and randomization, 48 patients underwent either dynamic augmented ACL suture repair or ACL reconstruction with a single-bundle, all-inside, semitendinosus technique. The International Knee Documentation Committee (IKDC) subjective score at 2 years postoperatively was the primary outcome measure. Patient-reported outcomes (IKDC subjective score, Knee injury and Osteoarthritis Outcome Score, Tegner score, visual analog scale for satisfaction), clinical outcomes (IKDC physical examination score, leg symmetry index for the quadriceps, hamstrings strength, and jump test battery), and radiological outcomes as well as adverse events including reruptures were recorded. Analyses were based on an intention-to-treat principle.

RESULTS

The lower limit for the median IKDC subjective score of the repair group (86.2) fell within the prespecified noninferiority margin, confirming noninferiority of dynamic augmented ACL suture repair compared with ACL reconstruction. No statistical difference was found between groups for median IKDC subjective score (repair, 95.4; reconstruction, 94.3). Overall, 2 reruptures (8.7%) occurred in the dynamic ACL suture repair group and 4 reruptures (19.0%) in the ACL reconstruction group; further, 5 repeat surgeries-other than for revision ACL surgery-took place in 4 patients from the dynamic ACL suture repair group (20.8%) and in 3 patients from the ACL reconstruction group (14.3%).

CONCLUSION

Dynamic augmented ACL suture repair is not inferior to ACL reconstruction in terms of subjective patient-reported outcomes as measured with the IKDC subjective score 2 years postoperatively. However, for reasons other than revision ACL surgery due to rerupture, a higher number of related adverse events leading to repeat surgery were seen in the dynamic augmented ACL suture repair group within 2 years postoperatively.

CLINICAL RELEVANCE

Dynamic augmented ACL suture repair might be a viable treatment option for patients with an acute ACL rupture.

REGISTRATION

NCT02310854 ( ClinicalTrials.gov identifier).

Mechanical properties of a hierarchical electrospun scaffold for ovine anterior cruciate ligament replacement

The anterior cruciate ligament (ACL) acts to stabilize the knee and prevent excessive motion of the tibia relative to the femur. Tears of the ACL are common and can result in pain and damage to surrounding tissues. Thus a torn ACL is often surgically replaced with an autograft or allograft material. Drawbacks to clinically available ACL grafts motivate the development of a tissue engineered ACL replacement. Our group has previously developed a polycaprolactone electrospun scaffold that mimics the hierarchical structure of the ACL. The goal of this study was to investigate the mechanical properties of the electrospun scaffold as an ACL replacement. Scaffold mechanical properties were assessed prior to implantation via stress relaxation and pull to failure testing. Following in vitro characterization, electrospun scaffolds and soft tissue grafts were implanted into ovine cadaver stifle joints as ACL replacements. Stifle joints with ACL replacements were tested via a simulated anterior drawer test as well as in situ stress relaxation and pull to failure tests and compared to stifle joints with the native ACL intact. Prior to implantation the scaffold matched the native ovine ACL well in the range of functional strains as evidenced by stress relaxation measures and the toe region stiffness. After implantation the scaffold was more similar to the native ACL than the soft tissue graft, particularly when it came to reducing joint laxity and matching stress relaxation measures. These results demonstrate that the electrospun scaffold has the potential to be a suitable material for ACL replacement. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:421-430, 2019.

Anterior cruciate ligament repair with Independent Suture Tape Reinforcement: a case series with 2-year follow-up

PURPOSE

The treatment of acute anterior cruciate ligament (ACL) ruptures with a repair technique has recently regained interest. A novel ACL repair technique was described using Independent Suture Tape Reinforcement with 2-year follow-up results.

METHODS

Forty-two consecutive patients with an acute ACL rupture undergoing repair using this technique were followed up for a minimum of 2 years. Patients with mid-substance, distal ACL ruptures, poor ACL tissue quality or retracted ACL remnants as well as patients with multi-ligament injuries were excluded. Knee Injury and Osteoarthritis Outcome Score (KOOS), Visual Analogue Pain Scale (VAS-pain), Veterans RAND 12 Item Health Survey (VR-12) and the Marx Activity scale were collected by online questionnaires. Two-year postoperative patients were asked by telephone if they had experienced a rerupture.

RESULTS

All the KOOS subscales improved significantly in comparison to the preoperative score. The largest improvement of all scores was seen at 3 months postoperatively which is significant in all cases. The KOOS sport and recreation showed a meaningful change and the largest improvement of the KOOS subscales at 3 months postoperatively, as well as the highest total improvement at 1 year postoperatively compared to preoperatively. The VAS-pain and VR-12 physical score improved significantly, however the Marx activity scale decreased significantly in comparison to preoperative scores. Two patients reported a rerupture (4.8%, CI 1.7-11.2%).

CONCLUSIONS

This is the first case series that described the 2-year follow-up results of patients with an acute, proximal ACL rupture, treated with the Independent Suture Tape Reinforcement repair technique. A meaningful KOOS sport and recreation change and significant improvements in the KOOS, VAS-pain and VR-12 physical scores as well as a significant decrease of the Marx activity scale in comparison to preoperative scores are demonstrated. Two of the 42 patients (4.8%) reported an ACL rerupture. Repair with this technique could be clinically relevant as a treatment option for patients with an acute, proximal ACL rupture which is not retracted and of good tissue quality.

LEVEL OF EVIDENCE

IV.

Dynamic augmentation restores anterior tibial translation in ACL suture repair: a biomechanical comparison of non-, static and dynamic augmentation techniques

PURPOSE

There is a lack of objective evidence investigating how previous non-augmented ACL suture repair techniques and contemporary augmentation techniques in ACL suture repair restrain anterior tibial translation (ATT) across the arc of flexion, and after cyclic loading of the knee. The purpose of this work was to test the null hypotheses that there would be no statistically significant difference in ATT after non-, static- and dynamic-augmented ACL suture repair, and they will not restore ATT to normal values across the arc of flexion of the knee after cyclic loading.

METHODS

Eleven human cadaveric knees were mounted in a test rig, and knee kinematics from 0° to 90° of flexion were recorded by use of an optical tracking system. Measurements were recorded without load and with 89-N tibial anterior force. The knees were tested in the following states: ACL-intact, ACL-deficient, non-augmented suture repair, static tape augmentation and dynamic augmentation after 10 and 300 loading cycles.

RESULTS

Only static tape augmentation and dynamic augmentation restored ATT to values similar to the ACL-intact state directly postoperation, and maintained this after cyclic loading. However, contrary to dynamic augmentation, the ATT after static tape augmentation failed to remain statistically less than for the ACL-deficient state after cyclic loading. Moreover, after cyclic loading, ATT was significantly less with dynamic augmentation when compared to static tape augmentation.

CONCLUSION

In contrast to non-augmented ACL suture repair and static tape augmentation, only dynamic augmentation resulted in restoration of ATT values similar to the ACL-intact knee and decreased ATT values when compared to the ACL-deficient knee immediately post-operation and also after cyclic loading, across the arc of flexion, thus allowing the null hypotheses to be rejected. This may assist healing of the ruptured ACL. Therefore, this study would support further clinical evaluation of dynamic augmentation of ACL repair.

Do Nonsteroidal Anti-Inflammatory Drugs Affect Tissue Healing After Arthroscopic Anterior Cruciate Ligament Reconstruction?

Background

Experimental studies have reported nonsteroidal anti-inflammatory drugs (NSAIDs) could impair tendon healing. The purpose of this study was to investigate whether NSAIDs could affect recovery of knee joint function in patients after anterior cruciate ligament (ACL) reconstruction.

Material/Methods

We enrolled 40 patients treated with celecoxib and 40 patients treated with tramadol, who underwent ACL reconstruction from January 2011 to December 2017. Visual analogue scale (VAS) and functional outcomes were collected and evaluated. The follow-up period was 12 months.

Results

In both groups, all patients obtained pain release after surgery, compared with that before surgery. But no significant differences were observed between the 2 groups in VAS scores. We also did not find any differences between the 2 groups at 1 year of follow-up, in terms of anterior drawer test, Lachman test, side-to-side laxity assessed by KT-2000, IKDC score, Lysholm score, and Tegner scale. However, the celecoxib group showed a reduced incidence of nausea compared to the tramadol group (P=0.048).

Conclusions

The use of NSAIDs after ACL reconstruction is relatively safe and could decrease adverse side effects which were caused by opioid drugs.

Partial Anterior Cruciate Ligament Ruptures: Advantages by Intraligament Autologous Conditioned Plasma Injection and Healing Response Technique-Midterm Outcome Evaluation

The historical treatment options for partial anterior cruciate ligament (ACL) ruptures were conservative therapy or ACL reconstruction by injured bundle or entire ACL replacement. In awareness of the regenerative potential of biologic agents such as mesenchymal stem cells or platelet rich plasma (PRP), the healing response technique was developed to preserve the injured ACL with better outcomes than the conservative therapy. Further improvement of this technique seems to be obtained by the additional application of PRP products. Thus, the aim of this study was to evaluate the midterm outcome after intraligament autologous conditioned plasma (ACP) by a clinical, scoring, and functional performance assessment. 42 patients were evaluated in this study. The failure rate was 9.5%. Outcome evaluation showed good to excellent results. The scores were IKDC subjective 83.2 (SD 14.5), Lysholm 85.5 (SD 15.5), Tegner 4.7 (SD 1.7), and Cincinnati 85.4 (SD 15.5) after a mean follow-up of 33 months. Clinical examination showed stable Lachman test, negative pivot shift phenomenon, and a significant reduction in AP-laxity compared to preoperative status (rolimeter preoperative: 1.9 (SD1.4); postoperative 0.6 (SD1.8), p=0.001) in all patients. Functional performance testing showed no significant differences between the injured and healthy side. Return to sport was achieved after a mean of 5.8 months (SD 3.6) in 71.1% of the included patients. In summary, this new treatment option revealed in midterm follow-up promising results to treat partial ACL lesions with a reduced need for conversion to ACL reconstruction and with a high percentage of return to preinjury sport activity.

Total Knee Arthroplasty in Patients With Prior Anterior Cruciate Ligament Reconstruction

BACKGROUND

Few studies have analyzed the outcomes of total knee arthroplasty (TKA) in patients with prior anterior cruciate ligament (ACL) reconstruction, and the reported outcomes are controversial. The purpose of this study is to assess if prior ACL reconstruction had any impact on the outcome of subsequent TKA.

METHODS

A matched case-control study was conducted in patients who underwent TKA, including 37 with prior ACL reconstruction and 37 patients without ACL reconstruction. Preoperative and postoperative clinical and radiological data were collected from a prospective arthroplasty database with a minimum follow-up of 5 years. The mean age was 69.6 years, and 59.4% were men. The Knee Society scores, Short Form-12, and Western Ontario and McMaster Universities questionnaires were used for functional evaluations. Visual analogue scale 0-10 was used for patient satisfaction.

RESULTS

The mean follow-up after TKA was 6.1 (range 5-7.3) years. Two patients in the ACL group developed knee stiffness requiring manipulation under anesthesia, while 1 patient in the control group suffered superficial wound infection. At last follow-up, no significant differences in functional or radiologic outcomes were found between both groups. The performance of TKA in ACL patients had increased technical difficulty and significantly longer time of surgery, but this had no influence on the outcomes. In the ACL group, 24 knees had technical difficulty in surgery. The main difficulty in most ACL patients was due to varus deformity and increased retraction of the medial soft structures which required progressive medial release. Other 2 knees had difficult knee exposure. One was an unexpected partial patellar tendon avulsion and the other required planned quadriceps snip.

CONCLUSION

TKA was an effective procedure for patients with prior ACL reconstruction. The surgeon should be warned of the possible difficulties in the knee exposure and possible need of medial release to obtain an appropriate ligament balance. However, these additional procedures had no negative effect on the outcomes of TKA.

A systematic review of long-term patient reported outcomes for the treatment of anterior cruciate ligament injuries in the skeletally immature

PURPOSE

To systematically review the available literature regarding outcomes for the treatment of anterior cruciate ligament (ACL) injuries in the skeletally immature at skeletal maturity or more than five years after surgery.

METHODS

A systematic search was performed of seven online databases for literature reporting patient reported outcomes for the treatment of ACL injuries in the skeletally immature. A systematic review of this literature was performed examining the outcomes and their association with skeletal immaturity and treatment techniques.

RESULTS

A total of 18 articles reported the outcomes of 425 subjects. The mean age at surgery ranged from 10.3 to 15 years. Mean follow-up ranged from 36 to 163 months. Ten studies followed up subjects until skeletal maturity. Mean outcome scores were similar for extraphyseal (Lysholm 96.2 (95.7 to 97.4), Tegner 6.75, IKDC 95.4 (94 to 100)) and transphyseal surgery (Lysholm 94.3 (84.6-100), Tegner 7.6 (6 to 8.7), International Knee Documentation Committee (IKDC) 93.6 (84 to 99)). However, the lower range boundary for Lysholm and IKDC was worse for the transphyseal group. The results for non-surgical treatments were worse (Lysholm 63.2, Tegner 4.8, IKDC 87). No significant differences were found in the incidence of limb-length discrepancy (p = 0.32), coronal plane growth disturbance (p = 0.48), graft rupture (p = 0.88) and persistent symptomatic instability (p = 0.11) with transphyseal and extraphyseal surgical techniques.

CONCLUSION

Both transphyseal and extraphyseal reconstructive techniques produced good patient reported outcomes, with no significant differences in the incidence of limb-length discrepancy, coronal plane growth disturbance, graft rupture and persistent symptomatic instability. They compare favourably with the repair techniques reviewed and the natural history of the condition. Further high-quality studies comparing the transphyseal and extraphyseal techniques are required.

LEVEL OF EVIDENCE

Level IV.

In Vitro and In Vivo Performance of Tissue-Engineered Tendons for Anterior Cruciate Ligament Reconstruction

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction is the current standard of care for ACL tears. However, the results are not consistently successful; autografts or allografts have certain disadvantages; and synthetic grafts have had poor clinical results.

PURPOSE

To determine if recellularization of decellularized tendons combined with mechanical stimulation in a bioreactor could replicate the mechanical properties of the native ACL and be successfully used for ACL reconstruction in vivo.

STUDY DESIGN

Controlled laboratory study.

METHODS

Porcine tibialis tendons were decellularized and then recellularized with human adult bone marrow-derived stem cells. Tendons were cultured in a tissue bioreactor that provided biaxial cyclic loading for up to 7 days. To reproduce mechanical stresses similar to those experienced by the ACL within the knee joint, the tendons were subjected to simultaneous tension and torsion in the bioreactor. Expression of tendon-specific genes and newly synthesized collagen and glycosaminoglycan were used to quantify the efficacy of recellularization and dynamic bioreactor culture. The ultimate tensile load to failure and stiffness of recellularized constructs were measured after dynamic stimulation. Finally, the tissue-engineered tendons were used to reconstruct the ACL in 24 pigs, and ultimate tensile load to failure and stiffness were assessed after 3 months.

RESULTS

Dynamic bioreactor culture significantly increased the expression of tendon-specific genes, the quantity of newly synthesized collagen and glycosaminoglycan, and the ultimate tensile load and stiffness of recellularized tendons. After in vivo reconstruction, the ultimate tensile load and stiffness of the tissue-engineered tendons increased significantly up to 3 months after surgery and were within 80% of the ultimate tensile load of the natural ACL.

CONCLUSION

This translational study indicates that recellularization and dynamic mechanical stimuli can significantly enhance matrix synthesis and ultimate tensile load of decellularized porcine tibialis tendons. This approach to tissue engineering can be very useful for ACL reconstruction and may overcome some of the disadvantages of autografts and allografts.

CLINICAL RELEVANCE

Dynamic bioreactor cultivation of tissue-engineered tendons may overcome the limitations of autografts and allografts.

A Review on Biomechanics of Anterior Cruciate Ligament and Materials for Reconstruction

The anterior cruciate ligament is one of the six ligaments in the human knee joint that provides stability during articulations. It is relatively prone to acute and chronic injuries as compared to other ligaments. Repair and self-healing of an injured anterior cruciate ligament are time-consuming processes. For personnel resuming an active sports life, surgical repair or replacement is essential. Untreated anterior cruciate ligament tear results frequently in osteoarthritis. Therefore, understanding of the biomechanics of injury and properties of the native ligament is crucial. An abridged summary of the prominent literature with a focus on key topics on kinematics and kinetics of the knee joint and various loads acting on the anterior cruciate ligament as a function of flexion angle is presented here with an emphasis on the gaps. Briefly, we also review mechanical characterization composition and anatomy of the anterior cruciate ligament as well as graft materials used for replacement/reconstruction surgeries. The key conclusions of this review are as follows: (a) the highest shear forces on the anterior cruciate ligament occur during hyperextension/low flexion angles of the knee joint; (b) the characterization of the anterior cruciate ligament at variable strain rates is critical to model a viscoelastic behavior; however, studies on human anterior cruciate ligament on variable strain rates are yet to be reported; (c) a significant disparity on maximum stress/strain pattern of the anterior cruciate ligament was observed in the earlier works; (d) nearly all synthetic grafts have been recalled from the market; and (e) bridge-enhanced repair developed by Murray is a promising technique for anterior cruciate ligament reconstruction, currently in clinical trials. It is important to note that full extension of the knee is not feasible in the case of most animals and hence the loading pattern of human ACL is different from animal models. Many of the published reviews on the ACL focus largely on animal ACL than human ACL. Further, this review article summarizes the issues with autografts and synthetic grafts used so far. Autografts (patellar tendon and hamstring tendon) remains the gold standard as nearly all synthetic grafts introduced for clinical use have been withdrawn from the market. The mechanical strength during the ligamentization of autografts is also highlighted in this work.

Transient Scleraxis Overexpression Combined with Cyclic Strain Enhances Ligament Cell Differentiation

Efforts to generate tissue-engineered anterior cruciate ligament replacements are limited by a lack of methods to derive mature ligament cells. Viral overexpression of the tendon/ligament marker scleraxis (Scx) can drive cell differentiation; however, the use of viral vectors hampers translation to clinical use. In this study, C3H10T1/2 cells were transiently transfected with expression vectors containing the full-length murine Scx cDNA and cultured in three-dimensional collagen hydrogels under static or cyclic strain for up to 14 days. β-galactosidase (LacZ) transfected cells served as controls. Cell morphology and gene expression for ligament-related genes, in addition to contraction (hydrogel width), mechanical properties, and glycosaminoglycan (GAG) and DNA content of hydrogels, were quantified and compared over time, between Scx and LacZ groups, and between static and cyclically strained constructs. Increased Scx expression was maintained for the entire 14-day study in both static and cyclically strained constructs. In static culture, overexpression of Scx resulted in greater cell elongation and construct contraction compared to LacZ controls. There were no differences in gene expression, DNA, or GAG content between Scx and LacZ constructs cultured under static conditions and no differences in DNA content between Scx and LacZ constructs. When exposed to cyclic strain, Scx-overexpressing cells maintained the elongated phenotype exhibited in static constructs, increased GAG production compared to static culture, and increased expression of the ligament-related genes collagen type I, decorin, and tenascin-C compared to strained LacZ controls. Cyclically strained constructs containing Scx-overexpressing cells had increased maximum load and stiffness compared to LacZ controls. The maintenance of increased Scx expression throughout the 14 day study and subsequent increases in ligament marker gene expression and mechanical properties with cyclic, but not static strain, suggest that transient transfection may be a viable alternative to viral transduction of Scx for ligament engineering studies and support a synergistic effect of Scx and mechanical strain on driving early ligament cell differentiation.

Intra-ligamentary autologous conditioned plasma and healing response to treat partial ACL ruptures

INTRODUCTION

Conservative treatment of partial ACL ruptures is associated with a high failure rate, and often patients undergo ACL reconstruction. ACL preservation by trephination of the ACL origin and application of Autologous Conditioned Plasma (ACP) seems to be an intriguing new treatment option to favour ACL tissue healing and avoid traditional reconstruction. The aim of this study was to describe the mid-term outcomes of this new ACL preserving technique.

MATERIALS AND METHODS

Twenty-four patients (mean age 41.8 years) affected by partial rupture of one or both ACL bundles were included in the present trial. The partial ACL tears were arthroscopically assessed and classified according to a new five step grading system. All patients were treated by trephination of the femoral ACL stump and intra-ligamentary application of ACP. The postoperative outcome was evaluated by both subjective scores and stability testing up to a mean of 25.1 months' follow-up. Adverse events and failure rate were also documented.

RESULTS

Clinical outcome was good to excellent with IKDC subjective 82.7 (SD 11.8), Lysholm 87.6 (SD 8.1), Tegner 5.3 (SD 2.1), Cincinnati 88.7 (SD 14.8). The failure rate (i.e. persisting knee instability assessed clinically or by rolimeter) was 12.5%. At objective measurements, knee joints showed a firm endpoint in Lachman test, negative pivot shift phenomenon and a significant reduction in AP-laxity compared to pre-operative status by rolimeter testing (p = 0.002). Return to sport practice was achieved after mean 4.8 months (SD 4.1).

CONCLUSIONS

ACL stump trephination and concomitant intra-ligamentary application of ACP revealed promising results at mid-term follow-up to treat partial ACL lesions.

Comparison of Lower Extremity Recovery After Anterior Cruciate Ligament Reconstruction With Transphyseal Hamstring Versus Extraphyseal Iliotibial Band Techniques in Skeletally Immature Athletes

Background

The influence of graft type on recovery after anterior cruciate ligament reconstruction (ACLR) has not been adequately studied in pediatric patients.

Purpose

To describe lower extremity functional recovery parameters at the 6-month mark after ACLR across 3 distinct groups of skeletally immature patients: pediatric male patients with transphyseal hamstring grafts (PM-HS), pediatric female patients with transphyseal hamstring grafts (PF-HS), and pediatric male patients with extraphyseal iliotibial band grafts (PM-ITB).

Study Design

Cohort study; Level of evidence, 3.

Methods

Thigh circumference, knee range of motion, lower extremity strength, dynamic balance, and hop test performance were assessed in all patients 6 months postoperatively. All participants were ≤15 years of age with open physes. The limb symmetry index was used to compare deficits between the operated and uninvolved limbs for all 3 groups (PM-HS, PF-HS, and PM-ITB). Analysis of variance with post hoc correction was employed.

Results

A total of 93 pediatric patients who underwent ACLR (PM-HS: n = 21 [mean age, 13.6 ± 1.0 years]; PF-HS: n = 33 [mean age, 13.4 ± 0.7 years]; PM-ITB: n = 39 [mean age, 12.5 ± 1.3 years]) were examined. There was no statistically significant difference in thigh circumference, range of motion, dynamic balance, or hop test performance between the groups. Of the various additional comparisons analyzed, there were statistical differences in hamstring strength deficits among the 3 groups (P = .004). The PM-HS group showed a greater hamstring strength deficit (-32.2% relative to healthy limb) than the PM-ITB group (-5.4% relative to healthy limb) (P = .012). The hamstring strength deficit of the PF-HS group (-18.7% relative to healthy limb) was less than that of the PM-HS group and greater than that of the PM-ITB group but not statistically significant in either case.

Conclusion

Significant hamstring strength deficits were detected in the PM-HS group compared with the PM-ITB group at 6 months following ACLR. Such findings may influence decisions regarding graft selection, timing of return to sports, and postoperative rehabilitation regimens.

POST-OPERATIVE CRITERION BASED REHABILITATION OF ACL REPAIRS: A CLINICAL COMMENTARY

The anterior cruciate ligament (ACL) is the most commonly reconstructed ligament of the knee. Most often, the goal of surgical reconstruction is to recreate stability within the knee and prevent joint degeneration. To date, clinical studies have not demonstrated the ability of various reconstruction techniques in establishing complete knee stability when comparing rates of osteoarthritis. Rates of osteoarthritis commonly resemble those of knees which have not be reconstructed and in this light, may not demonstrate a successful outcome. As modern medicine continues to develop and in the understanding of underlying biological processes grows, some surgeons have turned their attention back to an ACL repair technique. The purpose of this clinical commentary is to discuss the parameters associated with a phase progression for an isolated ACL repair. Physiological healing time frames, along with objective clinical assessment, following a criterion-based progression is described in accordance with post-operative healing parameters to serve as a reference for a rehabilitation specialist.

LEVEL OF EVIDENCE

5.

Molecular influence of anterior cruciate ligament tear remnants on chondrocytes: a biologic connection between injury and osteoarthritis

OBJECTIVE

Anterior cruciate ligament (ACL) injury initiates a cascade of events often leading to osteoarthritis (OA). ACL reconstruction does not alter the course of OA, suggesting that heightened OA risk is likely due to factors in addition to the joint instability. We showed that torn ACL remnants express periostin (POSTN) in the acute phase of injury. Considering that ACL injury predisposes to OA and that POSTN is associated with cartilage metabolism, we hypothesize that ACL injury affects chondrocytes via POSTN.

DESIGN

Cartilage was obtained from osteoarthritic patients and ACL remnants were collected from patients undergoing ACL reconstruction. Crosstalk between ACL remnants and chondrocytes was studied in a transwell co-culture system. Expression of POSTN and other anabolic and catabolic genes was assessed via real-time polymerase chain reaction (PCR). Immunostaining for periostin was performed in human and mouse cartilage. The impact of exogenous periostin and siRNA-mediated ablation of periostin on matrix metabolism and cell migration was examined. Furthermore, the effect of anabolic (transforming growth factor beta 1 [TGF-β1]) and catabolic (interleukin 1 beta [IL-1β]) factors on POSTN expression was investigated.

RESULTS

ACL remnants induced expression of POSTN, MMP13 and ADAMTS4. Periostin levels were significantly higher in osteoarthritic compared to normal cartilage. Exogenous periostin induced MMP13 expression and cell migration, and repressed COL1A1 expression while POSTN knockdown inhibited expression of both anabolic and catabolic genes and impeded cell migration. TGF-β1 and IL-1β treatment did not alter POSTN expression but influenced chondrocyte metabolism as determined by quantification of anabolic and catabolic genes via real-time PCR.

CONCLUSIONS

ACL remnants can exert paracrine effects on cartilage, altering cellular homeostasis. Over time, this metabolic imbalance could contribute to OA development.

Fibrin glue mediated delivery of bone anabolic reagents to enhance healing of tendon to bone

Tendon graft healing in bone tunnels for the fixation of intra-articular ligament reconstructions may limit clinical outcome by delaying healing. This study assesses the effects of hydrogel-mediated delivery of bone anabolic growth factors in a validated model of tendon-to-bone tunnel healing. Forty-five Wistar rats were randomly allocated into three groups (BMP2-treated, GSK126-treated, and placebo). All animals underwent a tendon-to-bone tunnel reconstruction. Healing was evaluated at 4 weeks by biomechanical assessment, micro-computed tomography (bone mineral density, bone volume, cross sectional area of bone tunnels), and traditional histology. Adverse events associated with the hydrogel-mediated delivery of drugs were not observed. Results of our biomechanical assessment demonstrated favorable trends in animals treated with bone anabolic factors for energy absorption (P = 0.116) and elongation (P = 0.054), while results for force to failure (P = 0.691) and stiffness (P = 0.404) did not show discernible differences. Cross sectional areas for BMP2-treated animals were reduced, but neither BMP2 nor GSK126 administration altered bone mineral density (P = 0.492) or bone volume in the bone tunnel. These results suggest a novel and positive effect of bone anabolic factors on tendon-to-bone tunnel healing. Histological evaluation confirmed absence of collagen fibers crossing the soft tissue-bone interface indicating immature graft integration as expected at this time point. Our study indicates that hydrogel-mediated delivery of BMP2 and GSK126 appears to be safe and has the potential to enhance tendon-to-bone tunnel healing in ligament reconstructions.

Anterior Cruciate Ligament Reconstruction With Amnion Biological Augmentation

Anterior cruciate ligament (ACL) ruptures are common and unfortunate injuries for many athletes. The standard therapy for ACL rupture is ACL reconstruction with either autograft, harvested from hamstring or patellar tendon, or allograft tendon from a tissue donor. Advances in tissue engineering have produced interventions to augment the healing process and may have applications when it comes to ACL reconstruction. In this Technical Note and accompanying video, we describe a simple technique to implant an amnion matrix graft with a tendon graft during ACL reconstruction. This procedure uses the proposed anti-inflammatory, scaffolding, and stem cell-producing effects of the amniotic membrane to biologically augment the healing process of an ACL reconstruction.

Biological augmentation of graft healing in anterior cruciate ligament reconstruction: a systematic review

Aims

The success of anterior cruciate ligament reconstruction (ACLR) depends on osseointegration at the graft-tunnel interface and intra-articular ligamentization. Our aim was to conduct a systematic review of clinical and preclinical studies that evaluated biological augmentation of graft healing in ACLR.

Materials and Methods

In all, 1879 studies were identified across three databases. Following assessment against strict criteria, 112 studies were included (20 clinical studies; 92 animal studies).

Results

Seven categories of biological interventions were identified: growth factors, biomaterials, stem cells, gene therapy, autologous tissue, biophysical/environmental, and pharmaceuticals. The methodological quality of animal studies was moderate in 97%, but only 10% used clinically relevant outcome measures. The most interventions in clinical trials target the graft-tunnel interface and are applied intraoperatively. Platelet-rich plasma is the most studied intervention, but the clinical outcomes are mixed, and the methodological quality of studies was suboptimal. Other biological therapies investigated in clinical trials include: remnant-augmented ACLR; bone substitutes; calcium phosphate-hybridized grafts; extracorporeal shockwave therapy; and adult autologus non-cultivated stem cells.

Conclusion

There is extensive preclinical research supporting the use of biological therapies to augment ACLR. Further clinical studies that meet the minimum standards of reporting are required to determine whether emerging biological strategies will provide tangible benefits in patients undergoing ACLR. Cite this article: Bone Joint J 2018;100-B:271-84.

A case report of anterior cruciate ligament and posterolateral corner reconstruction using tendon graft preserved in situ

INTRODUCTION

Combined anterior cruciate ligament (ACL) and posterolateral corner (PLC) reconstruction are a rare clinical entity in orthopedic literature, whose management requires different types of tendon grafts. Missed PLC injury leads to the failure of ACL repair due to the joint instability.

PRESENTATION OF CASE

We are presenting a case of posttraumatic right ACL, PLC and lateral meniscus injury. The patient was taken to theatre for arthroscopic meniscectomy, ACL and PLC reconstruction. We had to harvest bilateral Gracilis and semitendinosus tendon grafts. Intraoperatively, we used a pump and after meniscectomy and ACL reconstruction the knee was quite swollen; we opted to offer a two-staged procedure for PLC reconstruction. Hence we had to preserve the graft in situ for the next procedure. Posterolateral corner reconstruction was done in a week's time and preserved ligament was found to be intact.

DISCUSSION

The fact that we did not have a tissue bank or facilities for cryopreservation of the harvested tendons at -80 °C or with liquid nitrogen at -179 °C yet we had to keep the harvested tendons safe.

CONCLUSION

In case of absence of graft and bone bank, tendon graft was in situ and found intact and ready to be used after seven days.

Effect of COX-2 inhibition on tendon-to-bone healing and PGE2 concentration after anterior cruciate ligament reconstruction

BACKGROUND

Non-steroidal anti-inflammatory drugs are commonly used to reduce pain and inflammation in orthopaedic patients. Selective cyclooxygenase-2 (COX-2) inhibitors have been developed to minimize drug-specific side effects. However, they are suspected to impair both bone and tendon healing. The objective of this study is to evaluate the effect of COX-2 inhibitor administration on tendon-to-bone healing and prostaglandin E (PGE2) concentration.

METHODS

Thirty-two New Zealand white rabbits underwent reconstructions of the anterior cruciate ligaments and were randomized into four groups: Two groups postoperatively received a selective COX-2 inhibitor (Celecoxib) on a daily basis for 3 weeks, the two other groups received no postoperative COX-2 inhibitors at all and were examined after three or 6 weeks. The PGE2 concentration of the synovial fluid, the osseous integration of the tendon graft at tunnel aperture and midtunnel section, as well as the stability of the tendon graft were examined via biomechanic testing.

RESULTS

After 3 weeks, the PGE2 content of the synovial fluid in the COX-2 inhibitor recipients was significantly lower than that of the control group (p = 0.018). At the same time, the COX-2 inhibitor recipients had a significantly lower bone density and lower amount of new bone formation than the control group (p = 0.020; p = 0.028) in the tunnel aperture. At the 6-week examination, there was a significant increase in the PGE2 content within synovial fluid of the COX-2 inhibitor recipients (p = 0.022), whose treatment with COX-2 inhibitors had ended 3 weeks earlier; in contrast, the transplant stability decreased and was reduced by 37% compared to the controls.

CONCLUSIONS

Selective COX-2 inhibitors cause impaired tendon-to-bone healing, weaken mechanical stability and decrease PGE2 content of the synovial fluid. The present study suggests a reluctant use of COX-2 inhibitors when tendon-to-bone healing is intended.

Editorial Commentary: Adult Stem Cell Potential to Enhance Healing of the Anterior Cruciate Ligament

Even with the most accurate individualized, anatomic approach to anterior cruciate ligament (ACL) reconstruction, the potential for graft failure still exists, with reported retear rates as low as 5%, and even higher in female athletes or patients reconstructed with allograft. ACL graft healing is dependent on several factors, including anatomic placement, appropriate graft choice, proper technique, recovery time, and the biological environment of nature. If the double-bundle concept is followed and individualized for each patient's anatomic morphology, the ACL will biologically reform. The use of adult stem cells may help to contribute to the biological environment and aid in a faster healing time and quicker return to the preoperative state. There is a need for long-term studies and further research in human models to determine the optimal indication and environment for tissue healing with stem cell treatment.

Intrasubstance Anterior Cruciate Ligament Injuries in the Pediatric Population

Pediatric intrasubstance anterior cruciate ligament (ACL) tears have a significant epidemiologic impact as their numbers continue to grow globally. This review focuses on true pediatric intrasubstance ACL tears, which occur >400,000 times annually. Modifiable and non-modifiable risk factors include intercondylar notch width, ACL size, gender, landing mechanisms, and hormonal variations. The proposed mechanisms of injury include anterior tibial shear and dynamic valgus collapse. ACL tears can be associated with soft tissue and chondral defects. History and physical examination are the most important parts of evaluation, including the Lachman test, which is considered the most accurate physical examination maneuver. Imaging studies should begin with AP and lateral radiographs, but magnetic resonance imaging is very useful in confirming the diagnosis and preoperative planning. ACL injury prevention programs targeting high risk populations have been proven to reduce the risk of injury, but lack uniformity across programs. Pediatric ACL injuries were conventionally treated nonoperatively, but recent data suggest that early operative intervention produces best long term outcomes pertaining to knee stability, meniscal tear risk, and return to previous level of play. Current techniques in ACL reconstruction, including more vertically oriented tunnels and physeal sparing techniques, have been described to reduce the risk of physeal arrest and limb angulation or deformity. Data consistently show that autograft is superior to allograft regarding failure rate. Mean durations of postoperative therapy and return to sport were 7 ± 3 and 10 ± 3 months, respectively. These patients have good functional outcomes compared to the general population yet are at increased risk of additional ACL injury. Attempts at primary ACL repair using biological scaffolds are under investigation.

Biologic response of human anterior cruciate ligamentocytes on collagen-patches to platelet-rich plasma formulations with and without leucocytes

Due to the poor self-healing capacities of the anterior cruciate ligament, previous primary repair attempts have failed. To enhance biologic healing, platelet rich plasma and collagen scaffold have shown promise in animal models. Platelet rich plasma (PRP) is already used in several clinical applications although outcomes are quite debated. The purpose of this study was to examine the effects of different PRP formulations during 21 days: With leucocytes and pure PRP on human anterior cruciate ligament-derived ligamentocytes grown on collagen patches in 3D cell cultures in vitro. Three experimental groups were formed: 2.5% leucocyte rich PRP, 2.5% pure PRP, 20% leucocyte rich PRP, a negative control, and a positive control. Cell proliferation, cell phenotype on mRNA transcript level, and extracellular matrix production (total collagen and glycosaminoglycan content) were evaluated. DNA content and metabolic cell activity increased significantly in all groups on day 21 compared to day 7, except in the negative control. No changes in extracellular matrix production were detected. Different catabolic genes were induced depending on the concentration of leucocyte rich PRP. PRP with and without leucocytes treated anterior cruciate ligamentocytes significantly increased cell proliferation but not extracellular matrix production. However, the specific activation of different catabolic genes was dependent on the relative content of leucocytes. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2733-2739, 2017.

Development of Multilayered Chlorogenate-Peptide Based Biocomposite Scaffolds for Potential Applications in Ligament Tissue Engineering - An <i>In Vitro</i> Study

In this work, for the first time, chlorogenic acid, a natural phytochemical, was conjugated to a lactoferrin derived antimicrobial peptide sequence RRWQWRMKKLG to develop a self-assembled template. To mimic the components of extracellular matrix, we then incorporated Type I Collagen, followed by a sequence of aggrecan peptide (ATEGQVRVNSIYQDKVSL) onto the self-assembled templates for potential applications in ligament tissue regeneration. Mechanical properties and surface roughness were studied and the scaffolds displayed a Young’s Modulus of 169 MP and an average roughness of 72 nm respectively. Thermal phase changes were studied by DSC analysis. Results showed short endothermic peaks due to water loss and an exothermic peak due to crystallization of the scaffold caused by rearrangement of the components. Biodegradability studies indicated a percent weight loss of 27.5 % over a period of 37 days. Furthermore, the scaffolds were found to adhere to fibroblasts, the main cellular component of ligament tissue. The scaffolds promoted cell proliferation and displayed actin stress fibers indicative of cell motility and attachment. Collagen and proteoglycan synthesis were also promoted, demonstrating increased expression and deposition of collagen and proteoglycans. Additionally, the scaffolds exhibited antimicrobial activity against Staphylococcus epidermis bacteria, which is beneficial for minimizing biofilm formation if potentially used as implants. Thus, we have developed a novel biocomposite that may open new avenues to enhance ligament tissue regeneration.

Reconstruction of cranial cruciate ligament in rabbits using polyester implants saturated with PRP, antlerogenic stem cells MIC-1 and their homogenate

AIM OF THE STUDY

The attempt to limit the negative effects of polyester implants on the articular cavity by using preparations containing growth factors.

MATERIALS AND METHODS

Polyester implants used for the reconstruction of a rabbit's cranial cruciate ligament (CCL) were saturated with autogenic platelet-rich plasma (PRP), antlerogenic stem cells MIC-1 and their homogenate prior to the surgery. Six months after CCL reconstruction, morphological, and biochemical blood tests were carried out, including proteinogram and acute phase proteins. The knee joints were also examined macro- and microscopically.

RESULTS

The results, compared to the control group, showed a favorable effect of the PRP and homogenate of antlerogenic cells on limiting the inflammation caused by the presence of polyester implant in the knee joint. The addition of growth factors caused covering the implant faster with the recipient's connective tissue, thus contributing to reducing the inflammatory reaction of the articular capsule to the presence of polyester. At the same time, no enhanced local or general reaction of the rabbit organism was observed to the presence of xenogenic antlerogenic stem cells MIC-1 homogenate which, like the PRP, may provide an easily available source of growth factors, increasingly often used in regenerative medicine.

CONCLUSIONS

Applying antlerogenic stem cells, their homogenate or PRP increases the volume of connective tissue that surrounds and intertwines polyester CCL implant, separating it from synovial cavity environment.

Mechanical stretch and hypoxia inducible factor-1 alpha affect the vascular endothelial growth factor and the connective tissue growth factor in cultured ACL fibroblasts

PURPOSES

The adult human anterior cruciate ligament (ACL) has poor functional healing response. Hypoxia plays an important role in regulating the microenvironment of the joint cavity after ACL injury, however, its role in mechanical injury is yet to be examined fully in ACL fibroblasts. In this study, we used CoCl₂ to induce Hypoxia-inducible factor-1α (HIF-1α) in our experimental model to study its affect on matrix metalloproteinase-2 (MMP-2), vascular endothelial growth factor (VEGF), and connective tissue growth factor (CTGF) expression in ACL fibroblasts after mechanical stretch.

MATERIALS AND METHODS

Cell treatments were performed in the stretch chamber in all experimental groups. Quantitative real-time PCR was used to check mRNA expression levels of MMP-2, CTGF, VEGF, and HIF-1α. Western blot was used to detect the HIF-1α production. Enzyme-Linked immunosorbent assay was performed to check the VEGF and CTGF protein contents in supernatant. MMP-2 activity was assayed by gelatin zymography.

RESULTS

The real-time PCR results show that mechanical stretch or CoCl₂ treatment increases the expression of MMP-2, VEGF, CTGF, and HIF-1α; however, the combined effects of mechanical stretch and CoCl₂-induced HIF-1α increased MMP-2 production but decreased the VEGF and CTGF expression, compared to the CoCl₂ treatment group alone. Western blot analysis and ELISA also confirmed these results.

CONCLUSIONS

Our results demonstrated that mechanical stretch and CoCl₂-induced HIF-1α together increased the level of MMP-2 and decreased the levels of VEGF and CTGF in cultured ACL fibroblasts. The differential expression and production of HIF-1α, VEGF, MMP-2, and CTGF might help to explain the poor healing ability of ACL.

The influence of connective tissue growth factor on rabbit ligament injury repair

Objectives

The injured anterior cruciate ligament (ACL) is thought to exhibit an impaired healing response, and attempts at surgical repair have not been successful. Connective tissue growth factor (CTGF) is reported to be associated with wound healing, probably through transforming growth factor beta 1 (TGF-β1).

Methods

A rabbit ACL injury model was used to study the effect of CTGF on ligament recovery. Quantitative real-time PCR (qRT-PCR) was performed for detection of changes in RNA levels of TGF-β1, type 1 collagen (COL1), type 2 collagen (COL2), SRY-related high mobility group-box gene9 (SOX9), tissue inhibitor of metalloproteinase-1 (TIMP-1) and matrix metallopeptidase 13 (MMP-13). Expression of related proteins was detected by Western blotting.

Results

The current study showed that CTGF could promote the recovery of an injured anterior cruciate ligament. It can upregulate mRNA and expression of TGF-β1, COL1, COL2, SOX9, and tissue inhibitor of TIMP-1, and downregulate mRNA and expression of MMP-13, suggesting that the curative effect of CTGF on injured rabbit ligaments is through regulation of these cellular factors.

Conclusions

This finding revealed the healing role of CTGF in injured tissues and provides new possibilities of treating injured tissues and wound healing by using CTGF.

Cite this article: X. Sun, W. Liu, G. Cheng, X. Qu, H. Bi, Z. Cao, Q. Yu. The influence of connective tissue growth factor on rabbit ligament injury repair. Bone Joint Res 2017;6:399–404. DOI: 10.1302/2046-3758.67.BJR.2016-0255.R1.

Early Graft Tunnel Healing After Anterior Cruciate Ligament Reconstruction With Intratunnel Injection of Bone Marrow Mesenchymal Stem Cells and Vascular Endothelial Growth Factor

Background:

Bone marrow mesenchymal stem cells (BM-MSCs) are multipotent adult stem cells and have become an important source of cells for engineering tissue repair and cell therapy. Vascular endothelial growth factor (VEGF) promotes angiogenesis and contributes fibrous integration between tendon and bone during the early postoperative stage. Both MSCs and VEGF can stimulate cell proliferation, differentiation, and matrix deposition by enhancing angiogenesis and osteogenesis of the graft in the tunnel.

Hypothesis:

Injection of intratunnel BM-MSCs and VEGF enhances the early healing process of a tendon graft.

Study Design:

Controlled laboratory study.

Methods:

In this controlled animal laboratory study, each of 4 groups of rabbits underwent unilateral anterior cruciate ligament (ACL) reconstruction with use of the ipsilateral semitendinosus tendon. The rabbits received intratunnel injection of BM-MSCs and VEGF with a fibrin glue seal covering the distal tunnel at the articular site. Evaluation using magnetic resonance imaging (MRI), collagen type III expression, and biomechanical analyses were performed at 3- and 6-week intervals.

Results:

All parameters using MRI, collagen type III expression, and biomechanical analysis of pullout strength of the graft showed that application of intratunnel BM-MSCs and VEGF enhanced tendon-to-bone healing after ACL reconstruction.

Conclusion:

Intratunnel injections of BM-MSCs and VEGF after ACL reconstruction enhanced graft tunnel healing. Overall, the femoral tunnel that received BM-MSCs and VEGF had better advanced healing with increased collagen type III fibers and better outcomes on MRI and biomechanical analysis. MRI is the most reliable tool for clinical use in evaluating stages of ACL healing after reconstruction, since biopsy is an invasive procedure.

Phase-Specific Ground Reaction Force Analyses of Bilateral and Unilateral Jumps in Patients With ACL Reconstruction

Background:

In patients who have undergone anterior cruciate ligament (ACL) reconstruction, there is a weak correlation between subjective evaluation of knee function on questionnaires and clinical or biomechanical test results.

Hypothesis:

Patients with lower subjective knee function will demonstrate lower ground-reaction forces (GRFs) in the operated leg and greater GRF asymmetries in both phase-specific and functional data analysis (FDA) approaches compared with patients with higher subjective knee function.

Study Design:

Descriptive laboratory study.

Methods:

The GRFs of the operated and nonoperated legs of 40 patients who previously underwent ACL reconstruction (patellar tendon) were analyzed during unilateral and bilateral countermovement jumps at a mean 2.5 years after surgery. The patients were separated into 2 groups depending on their International Knee Documentation Committee (IKDC) Subjective Form score: low IKDC and high IKDC.

Results:

Both phase-specific and FDA approaches showed lower GRF values in the operated compared with the nonoperated leg within the low-IKDC group during bilateral jumps. Moreover, lower GRF values were also present in the operated and nonoperated legs in the low-IKDC group compared with those of the high-IKDC group. Differences in GRFs were predominantly observed during the eccentric deceleration phase of jumping.

Conclusion:

Patients with previous ACL reconstruction who have limited subjective knee function have lower GRF values and greater GRF asymmetries, suggesting the use of interlimb compensation strategies.

Clinical Relevance:

The study results lead to a better understanding of the motor control needed during the eccentric and concentric movement phases of unilateral and bilateral jumps in patients who have undergone ACL reconstruction.

Association of anterior cruciate ligament injury with knee osteoarthritis and total knee replacement: A retrospective cohort study from the Taiwan National Health Insurance Database

Objective

This study aimed to support the potential protective role of anterior cruciate ligament (ACL) reconstruction against the development of osteoarthritis (OA).

Methods

In this retrospective cohort study, the long-term results of ACL reconstruction in Taiwan were evaluated based on data from the National Health Insurance Research Database (NHIRD). In total, 8,769 eligible cases were included from 11,921 ACL-injured patients. The cumulative incidence rates of OA and total knee replacement (TKR) were analyzed using the Kaplan-Meier estimator. Cox proportional hazards models were applied to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) of OA.

Results

There was a lower cumulative incidence of OA among ACL-reconstructed patients (271, 33.1%) than among non-reconstructed patients (1,874, 40.3%; p < 0.001). Patients who underwent ACL reconstruction had a lower cumulative incidence of TKR during the follow-up period (0.6%) than the non-reconstructed patients (4.6%, p < 0.001). After adjusting for covariates, ACL-injured patients who underwent reconstruction within one month after ACL injury showed a significantly lower risk of OA than those who never underwent reconstruction (adjusted HR = 0.83, 95% CI = 0.69–0.99).

Conclusions

These results indicate that ACL reconstruction might not provide complete protection from OA development after traumatic knee injury but does yield a lower cumulative incidence of OA development and TKR. Moreover, based on the present study, ACL-injured patients should undergo reconstruction as early as possible (within one month) to lower the risk of OA.

Minimum Information for Studies Evaluating Biologics in Orthopaedics (MIBO): Platelet-Rich Plasma and Mesenchymal Stem Cells

BACKGROUND

A comprehensive approach to the evaluation of biologic therapies for musculoskeletal conditions is required to guide appropriate future use. Clinical studies evaluating platelet-rich plasma (PRP) and mesenchymal stem cells (MSCs) are limited by inadequate reporting of scientific details critical to outcome. We developed minimum reporting requirements for clinical studies evaluating PRP and MSCs using Delphi consensus methods.

METHODS

The need for consensus on the minimum reporting requirements for studies evaluating biologics was identified at the American Academy of Orthopaedic Surgeons/Orthopaedic Research Society (AAOS/ORS) Biologic Treatments for Orthopaedic Injuries Symposium in 2015 and the American Orthopaedic Society for Sports Medicine (AOSSM) Biologic Treatments for Sports Injuries II Think Tank in 2015. A working group facilitated the development of 2 expert consensus statements for PRP and MSCs using Delphi techniques. Exhaustive lists of items that could be reported on by clinical studies evaluating PRP or MSCs were generated by searching the published literature and protocols. PRP and MSC expert groups, each made up of 24 invited speakers at the AAOS and AOSSM symposia, were surveyed on 3 occasions to establish consensus on the inclusion of each item within minimum reporting guidelines. In addition to rating their agreement, the experts were encouraged to propose further items or modifications. Predefined criteria were used to refine item lists after each survey. Final lists were compiled into checklist statements by the working group.

RESULTS

For PRP, the working group identified 93 experimental information items from the literature. Twenty-three experts (96%) completed 3 rounds of surveys. After 3 rounds, 58 items generated consensus with >75% agreement and <5% disagreement. These items were compiled into a 23-statement checklist. For MSCs, 103 items were identified from the published literature. Twenty-three experts (96%) completed 3 rounds of surveys. After 3 rounds, the 61 items for which consensus was reached were compiled into a 25-statement checklist.

CONCLUSIONS

This study has established expert consensus on the minimum reporting requirements for clinical studies evaluating PRP and MSCs.

CLINICAL RELEVANCE

These checklists provide specifications for the minimum information that should be reported by clinical studies evaluating PRP or MSCs.

Permanent knee sensorimotor system changes following ACL injury and surgery

The cruciate ligaments are components of the knee capsuloligamentous system providing vital neurosensory and biomechanical function. Since most historical primary ACL repair attempts were unsuccessful, reconstruction has become the preferred surgery. However, an increased understanding of the efficacy of lesion-site scaffolding, innovative suturing methods and materials, and evolving use of biological healing mediators such as platelet-rich plasma and stem cells has prompted reconsideration of what was once believed to be impossible. A growing number of in vivo animal studies and prospective clinical studies are providing increasing support for this intervention. The significance of ACL repair rather than reconstruction is that it more likely preserves the native neurosensory system, entheses, and ACL footprints. Tissue preservation combined with restored biomechanical function increases the likelihood for premorbid neuromuscular control system and dynamic knee stability recovery. This recovery should increase the potential for more patients to safely return to sports at their desired intensity and frequency. This current concepts paper revisits cruciate ligament neurosensory and neurovascular anatomy from the perspective of knee capsuloligamentous system function. Peripheral and central nerve pathways and central cortical representation mapping are also discussed. Surgical restoration of a more physiologically sound knee joint may be essential to solving the osteoarthritis dilemma. Innovative rehabilitative strategies and outcome measurement methodologies using more holistic and clinically relevant measurements that closely link biomechanical and neurosensory characteristics of physiological ACL function are discussed. Greater consideration of task-specific patient physical function and psychobehavioral links should better delineate the true efficacy of all ACL surgical and non-surgical interventions. Level of evidence IV.

Changes in Joint Contact Mechanics in a Large Quadrupedal Animal Model After Partial Meniscectomy and a Focal Cartilage Injury

Acute mechanical damage and the resulting joint contact abnormalities are central to the initiation and progression of post-traumatic osteoarthritis (PTOA). Study of PTOA is typically performed in vivo with replicate animals using artificially induced injury features. The goal of this work was to measure changes in a joint contact stress in the knee of a large quadruped after creation of a clinically realistic overload injury and a focal cartilage defect. Whole-joint overload was achieved by excising a 5-mm wedge of the anterior medial meniscus. Focal cartilage defects were created using a custom pneumatic impact gun specifically developed and mechanically characterized for this work. To evaluate the effect of these injuries on joint contact mechanics, Tekscan (Tekscan, Inc., South Boston, MA) measurements were obtained pre-operatively, postmeniscectomy, and postimpact (1.2-J) in a nonrandomized group of axially loaded cadaveric sheep knees. Postmeniscectomy, peak contact stress in the medial compartment is increased by 71% (p = 0.03) and contact area is decreased by 35% (p = 0.001); the center of pressure (CoP) shifted toward the cruciate ligaments in both the medial (p = 0.004) and lateral (p = 0.03) compartments. The creation of a cartilage defect did not significantly change any aspect of contact mechanics measured in the meniscectomized knee. This work characterizes the mechanical environment present in a quadrupedal animal knee joint after two methods to reproducibly induce joint injury features that lead to PTOA.

Do ground reaction forces during unilateral and bilateral movements exhibit compensation strategies following ACL reconstruction?

PURPOSE

The aims of the study were (1) to evaluate the leg asymmetry assessed with ground reaction forces (GRFs) during unilateral and bilateral movements of different knee loads in anterior cruciate ligament (ACL) reconstructed patients and (2) to investigate differences in leg asymmetry depending on the International Knee Documentation Committee Subjective Form (IKDC) in order to identify potential compensation strategies.

METHODS

The knee function of 50 ACL reconstructed (patella tendon) patients was examined at 31 ± 7 months after the surgery. GRFs were quantified during the sit-to-stand and stand-to-sit test, the step-up and step-down test, and the two- and one-leg vertical jump. Further, the IKDC score, the anterior-posterior knee laxity, and the concentric torque of the quadriceps and hamstring muscles were evaluated.

RESULTS

Differences between the operated and non-operated leg were found in the knee laxity, the quadriceps torque, and GRFs. The patients with low IKDC scores demonstrated greater leg asymmetries in GRFs compared to the patients with high IKDC scores.

CONCLUSIONS

ACL reconstructed patients showed GRF asymmetries during unilateral and bilateral movements of different knee loads. Three compensation strategies were found in patients with low subjective knee function: (1) a reduced eccentric load, (2) an inter-limb compensation during bilateral movements, and (3) the avoidance of high vertical impact forces. These compensation strategies may be indicative of a protective adaptation to avoid excessive ACL strain. GRF measurements are practicable and efficient tools to identify individual compensation strategies during early rehabilitation.

The influence of connective tissue growth factor on rabbit ligament injury repair

Objectives

The injured anterior cruciate ligament (ACL) is deemed to exhibit an impaired healing response and attempts at surgical repair have not been successful. Connective tissue growth factor (CTGF) is reported to be associated with wound healing, probably through transforming growth factor beta1 (TGF-β1).

Methods

A rabbit ACL injury model was used to study the effect of CTGF on ligament recovery. Quantitative real-time PCR was performed for detection of changes in RNA levels of TGF-β1, type 1 collagen (COL-I), type 2 collagen (COL-II), SRY-related high mobility group-box gene9 (Sox9), metalloproteinase-1 (TIMP-1) as well as matrix metallopeptidase 13 (MMP-13). And expression of related proteins was detected by western blotting.

Results

The current study showed that CTGF could promote the recovery of inured anterior cruciate ligament. It can up-regulate the mRNA and expression of TGF-β1, COL-I, COL-II, Sox9, as well as the tissue inhibitor of TIMP-1, and down-regulated the mRNA and expression of MMP-13, suggesting the curative effect of CTGF on injured rabbit ligament is through regulating these cellular factors.

Conclusion

This finding revealed the mechanism of CTFG’s healing role in injured tissues and provided new possibilities of treating injured tissues and wound healing by using CTFG.

The effects of irradiation dose and storage time following treatment on the viscoelastic properties of decellularised porcine super flexor tendon

Decellularised porcine super flexor tendon (pSFT) offers a promising solution to the replacement of damaged anterior cruciate ligament. It is desirable to package and terminally sterilise the acellular grafts to eliminate any possible harmful pathogens. However, irradiation techniques can damage the collagen structure and consequently reduce the mechanical properties. The aims of this study were to investigate the effects of irradiation sterilisation of varying dosages on the viscoelastic properties of the decellularised pSFT.

Decellularised pSFT tendons were subjected to irradiation sterilisation using either 30 kGy gamma, 55 kGy gamma, 34 kGy E-beam, 15 kGy gamma, 15 kGy E-beam and (15 + 15) kGy E-beam (fractionated dose). Specimens then underwent stress relaxation testing at 0 and 12 months post sterilisation to determine whether any effect on the viscoelastic properties was progressive.

Significant differences were found which demonstrated that all irradiation treatments had an effect on the time-independent and time-dependent viscoelastic properties of irradiated tendons compared to peracetic acid only treated controls. No significant differences were found between the irradiated groups and no significant differences were found between groups at 0 and 12 months. These results indicate the decellularised pSFT graft has a stable shelf-life.

Gap formation following primary repair of the anterior cruciate ligament: A biomechanical evaluation

BACKGROUND

Historically, inconsistent and unpredictable results of open primary anterior cruciate ligament (ACL) repair were reported. Recently, however, good results of arthroscopic primary ACL repair of proximal tears have been reported. Purpose of this study was to assess the direct postoperative gap formation and maximum failure load following simulated knee motion after primary ACL repair.

METHODS

Six matched-paired human cadaveric knees (mean age: 52years, range: 48 to 56years) were used. After primary proximal ACL repair with either suture button fixation or suture anchor fixation, knees were cycled five, 50 and 100 times with a simulated active quadriceps force. Gap formation between the femoral wall and ligament was measured using a digital caliper and maximum failure load was tested.

RESULTS

Gap formation after five, 50 and 100cycles of the knee were 0.30mm (±0.23), 0.75mm (±0.55) and 0.97mm (±0.70), respectively, with no significant differences between both fixation techniques. The overall maximum failure load was 243N (±143) with no difference between both techniques. Most common failure mode was slipping of suture from the fixation.

CONCLUSION

Following proximal ACL repair, gap formation of approximately one millimeter was measured after repetitious knee cycling with mean maximum failure load of 243N. These findings are likely to be sufficient for careful early active range of motion (ROM) when extrapolating from other available studies. Future studies with second-look arthroscopy are necessary to assess the gap formation and healing in patients treated with primary repair.

Controlling joint instability delays the degeneration of articular cartilage in a rat model

OBJECTIVE

Joint instability induced by anterior cruciate ligament (ACL) transection is commonly considered as a predisposing factor for osteoarthritis (OA) of the knee; however, the influence of re-stabilization on the protection of articular cartilage is unclear. The aim of this study was to evaluate the effect of joint re-stabilization on articular cartilage using an instability and re-stabilization ACL transection model.

DESIGN

To induce different models of joint instability, our laboratory created a controlled abnormal joint movement (CAJM) group and an anterior cruciate ligament transection group (ACL-T). Seventy-five Wistar male rats were randomly assigned to the CAJM (n = 30), ACL-T (n = 30), or no treatment (INTACT) group (n = 15). Cartilage changes were assessed with soft X-ray analysis, histological and immunohistochemistry analysis, and real-time polymerase chain reaction (PCR) analysis at 2, 4, and 12 weeks.

RESULTS

Joint instability, as indicated by the difference in anterior displacement between the CAJM and ACL-T groups (P < 0.001), and cartilage degeneration, as evaluated according to the Osteoarthritis Research Society International (OARSI) score, were significantly higher in the ACL-T group than the CAJM group at 12 weeks (P < 0.001). Moreover, joint re-stabilization maintained cartilage structure (thickness [P < 0.001], surface roughness [P < 0.001], and glycosaminoglycan stainability [P < 0.001]) and suppressed tumor necrosis factor-alpha (TNF-α) and caspase-3 at 4 weeks after surgery.

CONCLUSION

Re-stabilization of joint instability may suppress inflammatory cytokines, thereby delaying the progression of OA. Joint instability is a substantial contributor to cartilage degeneration.

Comparison of intra-articular analgesics in arthroscopic anterior cruciate ligament reconstruction surgeries: A randomized controlled trial

Background and Aims:

Arthroscopic anterior cruciate ligament reconstruction (ACLR) is one of the most common knee surgeries done worldwide today. It involves immense pain at sites of graft harvest, tibial, and femoral tunnels, thereby delaying recovery and increased patient morbidity, and delayed rehabilitation. Various drugs and combination of drugs administered intra-articularly have been studied for analgesic efficacy. Our study gives an insight if there is any added advantage of additives morphine or clonidine to bupivacaine when compared to administering bupivacaine alone.

Material and Methods:

After obtaining the Institute Ethics Committee approval, ninety American Society of Anesthesiology I-II patients undergoing arthroscopic ACLR under spinal anesthesia were randomly assigned to one of three groups (Group B – bupivacaine alone 0.25%, Group BM – bupivacaine 0.25% with morphine 5 mg, Group BC – bupivacaine 0.25% with clonidine 150 mcg). At the end of procedure, 20 mL of the respective drug was administered intra-articularly and postoperative time duration to rescue analgesia, 24 h analgesic requirement, visual analog scale (VAS) score findings at rest and on movement were observed.

Results:

The mean duration of time to request for first rescue analgesia in minutes was significantly longer in Group BC 341.55 (103.66 SD) with P < 0.001. The VAS scores at that time point were least in Group BM 6.1 (1.7 SD), but not statistically significant. The 24 h analgesic consumption was least in Group B 2.24 (0.79 SD), but not statistically significant.

Conclusion:

Combination of bupivacaine and clonidine administered intra-articularly provided a longer duration of analgesia though the quality of analgesia was comparable between the three groups.

Management of Anterior Cruciate Ligament Injury: What's In and What's Out?

Sports medicine physicians have a keen clinical and research interest in the anterior cruciate ligament (ACL). The biomechanical, biologic, and clinical data researchers generate, help drive injury management and prevention practices globally. The current concepts in ACL injury and surgery are being shaped by technological advances, expansion in basic science research, resurging interest in ACL preservation, and expanding efforts regarding injury prevention. As new methods are being developed in this field, the primary goal of safely improving patient outcomes will be a unifying principle. With this review, we provide an overview of topics currently in controversy or debate, and we identify paradigm shifts in the understanding, management, and prevention of ACL tears.

Postinjury biomechanics of Achilles tendon vary by sex and hormone status

Achilles tendon ruptures are common injuries. Sex differences are present in mechanical properties of uninjured Achilles tendon, but it remains unknown if these differences extend to tendon healing. We hypothesized that ovariectomized females (OVX) and males would exhibit inferior postinjury tendon properties compared with females. Male, female, and OVX Sprague-Dawley rats (n = 32/group) underwent acclimation and treadmill training before blunt transection of the Achilles tendon midsubstance. Injured hindlimbs were immobilized for 1 wk, followed by gradual return to activity and assessment of active and passive hindlimb function. Animals were euthanized at 3 or 6 wk postinjury to assess tendon structure, mechanics, and composition. Passive ankle stiffness and range of motion were superior in females at 3 wk; however, by 6 wk, passive and active function were similar in males and females but remained inferior in OVX. At 6 wk, female tendons had greater normalized secant modulus, viscoelastic behavior, and laxity compared with males. Normalized secant modulus, cross-sectional area and tendon glycosaminoglycan composition were inferior in OVX compared with females at 6 wk. Total fatigue cycles until tendon failure were similar among groups. Postinjury muscle fiber size was better preserved in females compared with males, and females had greater collagen III at the tendon injury site compared with males at 6 wk. Despite male and female Achilles tendons withstanding similar durations of fatigue loading, early passive hindlimb function and tendon mechanical properties, including secant modulus, suggest superior healing in females. Ovarian hormone loss was associated with inferior Achilles tendon healing.

Primary Repair of Tibial-Sided Avulsion of the Anterior Cruciate Ligament

Lesions of the anterior cruciate ligament (ACL) are common; the current gold standard of treatment for such lesions is ACL reconstruction. Tibial-sided soft-tissue avulsion is a rare subtype of ACL injuries. Unlike femoral-sided ACL repair, surgery for acute tibial-sided ACL ruptures has been neither reported nor described. This technical note presents a method for primary anatomic ACL reinsertion for an acute distal soft-tissue avulsion-type ACL injury, using a transosseous pull-out repair technique. Our technique, as an alternative to reconstruction, has the potential to enhance healing due to marrow stimulation (tibial tunneling). It also preserves the native insertion site and proprioceptive function, which may, in turn, reduce the risk of post-traumatic osteoarthritis.

Strain Response of the Anterior Cruciate Ligament to Uniplanar and Multiplanar Loads During Simulated Landings: Implications for Injury Mechanism

BACKGROUND

Despite basic characterization of the loading factors that strain the anterior cruciate ligament (ACL), the interrelationship(s) and additive nature of these loads that occur during noncontact ACL injuries remain incompletely characterized.

HYPOTHESIS

In the presence of an impulsive axial compression, simulating vertical ground-reaction force during landing (1) both knee abduction and internal tibial rotation moments would result in increased peak ACL strain, and (2) a combined multiplanar loading condition, including both knee abduction and internal tibial rotation moments, would increase the peak ACL strain to levels greater than those under uniplanar loading modes alone.

STUDY DESIGN

Controlled laboratory study.

METHODS

A cadaveric model of landing was used to simulate dynamic landings during a jump in 17 cadaveric lower extremities (age, 45 ± 7 years; 9 female and 8 male). Peak ACL strain was measured in situ and characterized under impulsive axial compression and simulated muscle forces (baseline) followed by addition of anterior tibial shear, knee abduction, and internal tibial rotation loads in both uni- and multiplanar modes, simulating a broad range of landing conditions. The associations between knee rotational kinematics and peak ACL strain levels were further investigated to determine the potential noncontact injury mechanism.

RESULTS

Externally applied loads, under both uni- and multiplanar conditions, resulted in consistent increases in peak ACL strain compared with the baseline during simulated landings (by up to 3.5-fold; P ≤ .032). Combined multiplanar loading resulted in the greatest increases in peak ACL strain (P < .001). Degrees of knee abduction rotation (R(2) = 0.45; β = 0.42) and internal tibial rotation (R(2) = 0.32; β = 0.23) were both significantly correlated with peak ACL strain (P < .001). However, changes in knee abduction rotation had a significantly greater effect size on peak ACL strain levels than did internal tibial rotation (by ~2-fold; P < .001).

CONCLUSION

In the presence of impulsive axial compression, the combination of anterior tibial shear force, knee abduction, and internal tibial rotation moments significantly increases ACL strain, which could result in ACL failure. These findings support multiplanar knee valgus collapse as one the primary mechanisms of noncontact ACL injuries during landing.

CLINICAL RELEVANCE

Intervention programs that address multiple planes of loading may decrease the risk of ACL injury and the devastating consequences of posttraumatic knee osteoarthritis.