Donor-site morbidity and anterior knee problems after anterior cruciate ligament reconstruction using autografts

Physiotherapy after reconstruction of anterior cruciate ligament

The purpose of this study was to evaluate the existence of differences in the rehabilitation of patients after ACL reconstruction using bone-patellar tendon-bone graft and the four-strand semitendinosus and gracilis tendon grafts, through a literature revision. The researched databases were MEDLINE, EMBASE, LILACS, COCHRANE and PEDro. The inclusion criteria were published studies with methodology draw from randomized clinical trials with or without meta-analysis, individuals with ACL injury, associated or not to meniscal injury, submitted to ligamentoplasty using the bone-patellar tendon-bone graft and the four-strand semitendinosus and gracilis tendon grafts and physiotherapy; clinical trials comparing the differences in the rehabilitation of these patients, in Portuguese, English and Spanish, from 1990 to June, 2011. Five clinical trials were reviewed. No difference was observed between the techniques, however, with a recommendation for a less aggressive rehabilitation and greater attention to the strengthening of the hamstring when they are used as grafts.

Design Considerations for a Prosthetic Anterior Cruciate Ligament

Anterior cruciate ligament (ACL) tearing is a common knee injury often requiring reconstruction with an autograft or an allograft. A prosthetic ligament replacement with off-the-shelf availability could potentially provide significant advantages over the current options for both patients and surgeons. Limitations of previous prosthetics include lack of biocompatibility and susceptibility to fatigue, creep, and failure of bony incorporation. This paper describes design considerations and possible improvements for the next generation prosthetic ACL. Design controls, as mandated by the FDA, are a systematic set of practices within the design and development process used to ensure that a new medical device meets the needs of the intended users. The specified requirements, called the design inputs, for a prosthetic ACL are discussed pertaining to material and structural properties, resistance to creep and fatigue, ability to support secure initial fixation, biocompatibility, and long-term osseointegration. Design innovations to satisfy the design inputs are discussed with regards to material selection, textile pattern, bone tunnel features, and short term fixation. A risk analysis is presented along with descriptions of proposed testing. Design control methodology and tissue engineering may be used to develop a next generation prosthetic ligament, solving multiple problems, simultaneously, on a holistic level, providing major improvements over earlier devices and current treatment options.

Donor-site-related functional problems following anterior cruciate ligament reconstruction: development of a self-administered questionnaire

PURPOSE

To develop a self-administered questionnaire for the evaluation of donor-site-related functional problems after anterior cruciate ligament (ACL) reconstruction with autograft harvested from the hamstring tendon or patellar tendon and to determine the content validity, reliability and preliminary factor structure of this new instrument.

METHODS

Seven physiotherapists with long clinical experience of rehabilitation after ACL reconstruction and 60 patients from the target population participated as experts in the developmental stages of the questionnaire. Content validity was determined and quantified with the content validity index (CVI). Test-retest reliability, internal consistency and factor structure were evaluated in another 64 patients reconstructed with an autograft.

RESULTS

The final questionnaire included 16 items on symptoms and function during activities of daily living and exercise. Excellent content validity on both item level (I-CVI ≥ 0.83, range 0.83-1.00) and scale level (S-CVI = 0.93) was found. The test-retest reliability was good, ICC = 0.94. Internal consistency was high, and Cronbach's α was 0.92 and 0.94 at each test occasion. The principal components analysis yielded a four-component structure.

CONCLUSIONS

The questionnaire "Donor-site-Related Functional Problems following Anterior Cruciate Ligament (ACL) Reconstruction" is a patient-reported questionnaire with high content validity and reliability for the evaluation of donor-site-related functional problems after ACL reconstruction, with autograft harvested from the hamstring tendon or patellar tendon. The results of this study support the use of this questionnaire as a standardized outcome measure for both research purposes and in clinical settings.

A novel technique for conduction studies of the infrapatellar nerve

OBJECTIVE

To introduce a noninvasive method for electrodiagnostic evaluation of the infrapatellar nerve (IPN).

DESIGN

A prospective cohort study.

SETTING

Electrodiagnostic laboratory, rehabilitation department, Hadassah University Hospital.

PARTICIPANTS

A total of 38 healthy adults; 57 asymptomatic limbs were studied.

METHODS

Sensory nerve action potential of the IPN was recorded with surface electrodes placed 2.5 cm below the distal pole of the patella and 2 cm medially from the medial border of the patellar tendon. Transcutaneous antidromic electrical stimulation of IPN was applied above the medial femoral condyle and 8-10 cm proximally from the active surface electrode.

RESULTS

The sensory nerve action potential mean (n = 38) onset latency was 1.69 ± 0.32 ms. Peak latency was 2.36 ± 0.47 ms, and amplitude was 6.96 ± 3.68 μV.

CONCLUSIONS

This article describes a novel and simple technique for IPN conduction electrodiagnostic examination. The method used provides a new tool to evaluate IPN injury in reference to anterior or inferior knee pain with associated sensory deficit.

A tale of 10 European centres - 2010 APOSSM travelling fellowship review in ACL surgery

The purpose of ESSKA- APOSSM Travelling fellowship is to better understand the epidemiology, management and surgical techniques for sports across continents. There has been a progressive evolution in ACL reconstruction and there is variation in technique in ACL reconstruction amongst the most experienced surgeons in different continents. During this one month fellowship, we saw various ACL reconstruction techniques using different graft sources, with a variety of graft fixation methods, with the common aim of recreating an anatomical ACL reconstruction.

Bone-patellar tendon-bone graft via a single minimally-invasive approach versus a classical approach in anterior cruciate ligament reconstruction: a prospective study

Harvesting the patellar ligament for anterior cruciate ligament reconstructions can be a source of anterior knee pain and hypoesthesia of the lateral side of the knee. We analyzed the feasibility of a minimally-invasive technique via a single patellar approach and postulate that it reduces anterior pain and limits the hypoesthesia area.

PATIENTS AND METHODS

A prospective, comparative, non-randomized, single-center study was conducted on two groups: one undergoing surgery with the classical anteromedial approach, the other with the minimally-invasive approach. Each group included 20 patients. Both series were reviewed between the 6th and 8th month after surgery. The revision was clinical, radiological, and ultrasonographic.

RESULTS

The grafts harvested via the classical approach in all 20 cases presented good characteristics, versus eight out of 18 for the grafts harvested via the minimally-invasive approach. A prominent anterior tibial tuberosity improved the quality of the tibial bone block. A hypoesthesia zone was found in 16 cases out of 18 in the classical approach group, it measured a mean 10.3 ± 5.6 cm(2). A surface area of 3 cm(2) was noted in one case from the minimally-invasive group. No significant difference was found for the subjective and objective IKDC and Lille patellofemoral scores between the two groups. Anterior pain was present in four patients in the classical group and six in the minimally-invasive group.

DISCUSSION

The minimally-invasive technique reduces the risk of cutaneous hypoesthesia. It does not prevent anterior pain related to harvesting the patellar tendon and a good-quality transplant can be obtained if the anterior tibial tuberosity is prominent.

LEVEL OF EVIDENCE

Level III: case-control study.

A between sex comparison of anterior-posterior knee laxity after anterior cruciate ligament reconstruction with patellar tendon or hamstrings autograft: a systematic review

Anterior-posterior (AP) knee laxity after anterior cruciate ligament (ACL) reconstruction may differ between sexes for different graft types. Females may experience an increase in AP knee laxity following an ACL reconstruction with a hamstrings graft, which is not seen in males with a hamstrings graft or in males or females with a bone-patellar tendon-bone (BTB) graft. The hypothesis of this review is sex differences in AP knee laxity and this will be identified in patients who undergo an ACL reconstruction with a hamstrings graft, while no sex differences will be observed in patients who have an ACL reconstruction with a BTB graft. A systematic search was performed in PubMed, CINAHL and SPORTDiscus. Inclusion criteria were articles published in the English language that studied human subjects who underwent an ACL reconstruction with a BTB or hamstrings autograft, and the presence of a sex comparison on outcome measures including side-to-side difference in AP knee laxity. Methodological quality was assessed using a Modified Coleman Methodology Score. Eleven cohort studies met the inclusion criteria. Six investigated sex differences in both hamstrings and BTB grafts. Three only investigated BTB grafts and two only investigated hamstrings grafts. These studies consistently reported increases in AP knee laxity in females after an ACL reconstruction with a hamstrings graft that was not observed in the other cohorts. This systematic review indicates that female patients have greater AP knee laxity following an ACL reconstruction with a hamstrings autograft compared with males with a similar procedure, and both females and males following an ACL reconstruction with a BTB autograft. These results are derived from lower level evidence, as no randomized control trials have attempted to answer this question. Future studies need to rigorously address this clinical question to confirm the results currently in the literature.

Monitoring sinew contraction during formation of tissue-engineered fibrin-based ligament constructs

The ability to study the gross morphological changes occurring during tissue formation is vital to producing tissue-engineered structures of clinically relevant dimensions in vitro. Here, we have used nondestructive methods of digital imaging and optical coherence tomography to monitor the early-stage formation and subsequent maturation of fibrin-based tissue-engineered ligament constructs. In addition, the effect of supplementation with essential promoters of collagen synthesis, ascorbic acid (AA) and proline (P), has been assessed. Contraction of the cell-seeded fibrin gel occurs unevenly within the first 5 days of culture around two fixed anchor points before forming a longitudinal ligament-like construct. AA+P supplementation accelerates gel contraction in the maturation phase of development, producing ligament-like constructs with a higher collagen content and distinct morphology to that of unsupplemented constructs. These studies highlight the importance of being able to control the methods of tissue formation and maturation in vitro to enable the production of tissue-engineered constructs with suitable replacement tissue characteristics for repair of clinical soft-tissue injuries.

Graft-dependent differences in the ligamentization process of anterior cruciate ligament grafts in a sheep trial

PURPOSE

The structural properties of the healing ligament are the determining factor for the stability of the reconstruction before, during, and after osseous integration of anterior cruciate ligament grafts. Over the course of ligamentization, the stability of synovialized grafts seems lower than that of non-synovialized patellar tendon grafts.

METHODS

In an animal study on 42 sheep, 21 non-synovialized grafts (patellar tendon) and 21 synovialized grafts (flexor digitorum superficialis tendon) were performed to replace the anterior cruciate ligament. After 6, 12, and 24 weeks, 7 animals from each group were euthanized and investigated. Anteroposterior stability of the knee was assessed. After removal of all other soft tissues, the ACL was loaded to failure. Histology and histological analysis of the intra-articular graft region was then performed.

RESULTS

There were no significant differences in the translation test comparing synovialized and non-synovialized grafts. After 6, 12, and 24 weeks, all transplants failed in the tensile test due to interligamentous rupture or avulsion. After 6 weeks, transplants did not show significant biomechanical differences. Load to failure and stiffness of the patellar tendon was more than twice those of synovialized tendon (P = 0.002) after 12 weeks. Histology revealed necrosis in patellar tendon specimens after 12 weeks. A significant increase in load to failure was determined in synovialized ligament grafts between 12 and 24 weeks (P = 0.005). Its load capacity then tended to be higher than that of patellar tendon grafts.

CONCLUSION

The stability of synovialized ligament grafts is significantly lower than that of non-synovialized patellar tendon grafts after 12 weeks. This difference is compensated after 24 weeks. The significantly lower load to failure of synovialized compared with non-synovialized grafts after 12 weeks may be clinically relevant for the rehabilitation process of anterior cruciate ligament grafts in humans.

Allograft anterior cruciate ligament reconstruction: indications, techniques, and outcomes

The anterior cruciate ligament (ACL) is an important stabilizer of the knee against translational and rotational forces. The goal of anatomic reconstruction of the ACL-deficient knee is to re-create a stable knee that will allow for return to sport and prevent recurrent injury. Multiple graft options exist for ACL reconstruction, and each option has unique advantages and disadvantages. With appropriate patient selection, each graft can be utilized to optimize patient outcomes. Allograft options limit morbidity following ACL reconstruction, but care must be taken with surgical technique and postoperative rehabilitation to allow for graft incorporation. An understanding of the surgical technique and differences between graft options will allow the patient, surgeon, and physical therapist to maximize outcomes following ACL reconstruction.

Inactivation Effect of Standard and Fractionated Electron Beam Irradiation on Enveloped and Non-Enveloped Viruses in a Tendon Transplant Model

BACKGROUND: For increasing allograft tendon safety in reconstructive surgery, an effective sterilization method achieving sterility assurance including viruses without impairing the grafts properties is needed. Fractionated Electron Beam (Ebeam) has shown promising in vitro results. The proof of sufficient virus inactivation is a central part of the process validation. METHODS: The Ebeam irradiation of the investigated viruses was performed in an optimized manner (oxygen content < 0.1%, -78 °C). Using principles of a tendon model the virus inactivation kinetics for HIV-2, HAV, pseudorabies virus (PRV) and porcine parvovirus (PPV) were calculated as TCID(50)/ml and D(10) value (kGy) for the fractionated (10 × 3.4 kGy) and the standard (1 × 34 kGy) Ebeam irradiation. RESULTS: All viruses showed comparable D(10) values for both Ebeam treatments. For sufficient virus titer reduction of 4 log(10) TCID(50)/ml, a dose of 34 kGy of the fractionated Ebeam irradiation was necessary in case of HIV-2, which was the most resistant virus investigated in this study. CONCLUSION: The fractionated and the standard Ebeam irradiation procedure revealed comparable and sufficient virus inactivation capacities. In combination with the known good biomechanical properties of fractionated Ebeam irradiated tendons, this method could be a safe and effective option for the terminal sterilization of soft tissue allografts.

Current concepts for anterior cruciate ligament reconstruction: a criterion-based rehabilitation progression

The management of patients after anterior cruciate ligament reconstruction should be evidence based. Since our original published guidelines in 1996, successful outcomes have been consistently achieved with the rehabilitation principles of early weight bearing, using a combination of weight-bearing and non-weight-bearing exercise focused on quadriceps and lower extremity strength, and meeting specific objective requirements for return to activity. As rehabilitative evidence and surgical technology and procedures have progressed, the original guidelines should be revisited to ensure that the most up-to-date evidence is guiding rehabilitative care. Emerging evidence on rehabilitative interventions and advancements in concomitant surgeries, including those addressing chondral and meniscal injuries, continues to grow and greatly affect the rehabilitative care of patients with anterior cruciate ligament reconstruction. The aim of this article is to update previously published rehabilitation guidelines, using the most recent research to reflect the most current evidence for management of patients after anterior cruciate ligament reconstruction. The focus will be on current concepts in rehabilitation interventions and modifications needed for concomitant surgery and pathology.

LEVEL OF EVIDENCE

Therapy, level 5.

Tenogenic differentiation of human MSCs induced by the topography of electrochemically aligned collagen threads

Topographical cues from the extracellular microenvironment can influence cellular activity including proliferation and differentiation. Information on the effects of material topography on tenogenic differentiation of human mesenchymal stem cells (human MSCs) is limited. A methodology using the principles of isoelectric focusing has previously been developed in our laboratory to synthesize electrochemically aligned collagen (ELAC) threads that mimics the packing density, alignment and strength of collagen dense connective tissues. In the current study, human MSCs were cultured on ELAC and randomly oriented collagen threads and the effect of collagen orientation on cell morphology, proliferation and tenogenic differentiation was investigated. The results indicate that higher rates of proliferation were observed on randomly oriented collagen threads compared to ELAC threads. On the other hand, tendon specific markers such as scleraxis and tenomodulin, were significantly increased on ELAC threads compared to randomly oriented collagen threads. Additionally, osteocalcin, a specific marker of bone differentiation was suppressed on ELAC threads. Previous studies have reported that BMP-12 is a key growth factor to induce tenogenic differentiation of MSCs. To evaluate the synergistic effect of BMP-12 and collagen orientation, human MSCs were cultured on ELAC threads in culture medium supplemented with and without BMP-12. The results revealed that BMP-12 did not have an additional effect on the tenogenic differentiation of human MSCs on ELAC threads. Together, these results suggest that ELAC induces tenogenic differentiation of human MSCs by presenting an aligned and dense collagen substrate, akin to the tendon itself. In conclusion, ELAC has a significant potential to be used as a tendon replacement and in the development of an osteotendinous construct towards the regeneration of bone-tendon interfaces.

Arthrofibrosis after anterior cruciate ligament reconstruction in children and adolescents

INTRODUCTION

Arthrofibrosis is a known complication after anterior cruciate ligament (ACL) reconstruction. ACL reconstruction is being performed with increased frequency in the pediatric population. The purpose of this study was to determine the prevalence of arthrofibrosis in children and adolescents and to identify risk factors for arthrofibrosis.

METHODS

The study design was a retrospective case series. Medical records for 1016 consecutive ACL reconstructions in patients aged 7 to 18 years old between 1995 to 2008 at a major tertiary care children's hospital were reviewed to identify cases of postoperative arthrofibrosis. Arthrofibrosis was defined as a loss of 5 degrees or more extension compared with the contralateral knee that required a follow-up procedure or a loss of 15 degrees or more flexion compared with the contralateral knee that required a follow-up procedure. Patient data were recorded and analyzed using bivariate models to identify predictors for arthrofibrosis. Further, we reviewed the clinical course of patients with treated arthrofibrosis to assess functional outcomes of this complication.

RESULTS

Nine hundred two patients with 933 knees met the inclusion criteria for this study, of which 60% were female. The mean age at the time of surgery was 15 years (range, 7 to 18 y), and the average follow-up from original ACL reconstruction was 6.3 years (range, 1.6 to 14.2 y). The overall prevalence of arthrofibrosis in our cohort was 8.3%, with 77 of the 933 knees had at least 1 procedure to treat arthrofibrosis after ACL reconstruction. Risk factors for arthrofibrosis were female sex (11.1% females, P = 0.0001), patients aged 16 to 18 years [11.6%; odds ratio (OR) 3.51; P = 0 .007], patellar tendon autograft (OR, 1.7; P = 0.026), and concomitant meniscal repair (OR, 2.08; P = 0.007). Prior knee surgery and ACL reconstruction within 1 month of injury were not significantly associated with arthrofibrosis after ACL reconstruction. Fifty-three patients had a minimum of 6 months clinical follow-up after the procedure for arthrofibrosis. Of these, 46 patients (86.8%) had full range of motion at follow-up. Thirty-two patients (60.4%) were asymptomatic at final follow-up. Eleven patients (20.8%) complained of some persistent pain.

CONCLUSIONS

The rate of arthrofibrosis after ACL reconstruction in children and adolescents is 8.3%. Risk factors for arthrofibrosis are female sex, older adolescents, concurrent meniscal repair, and reconstruction with patellar tendon autograft. Surgical treatment for arthrofibrosis after ACL reconstruction in pediatric patients can satisfactorily regain motion in the reconstructed knee; however functional outcome may be compromised.

LEVEL OF EVIDENCE

Level 4.

Lateral thigh fascia lata as interpositional graft for temporomandibular joint ankylosis

Successful management of temporomandibular joint (TMJ) ankylosis depends on adequate gap arthroplasty and interpositional graft; the objective is to produce a functioning pseudoarthrosis that prevents reankylosis and provides adequate mobility. Several interpositional grafts have been used for the treatment of temporomandibular joint ankylosis such as indigenous pterygomasseteric sling, temporalis muscle/fascia, auricular cartilage, fat and dermis-fat. Lateral thigh fascia lata (LTFL) graft is commonly used in neurosurgical practice and in other surgical specialities. We present a case of lateral thigh fascia lata used as interpositional graft for the treatment of a unilateral fibrous temporomandibular joint ankylosis.

Mini-invasive technique for bone patellar tendon bone harvesting: its superiority in reducing anterior knee pain following ACL reconstruction

Arthroscopically-assisted ACL-reconstructions are currently reliable, reproducible. Residual anterior knee symptoms however, especially after patellar-BTB graft use, are not uncommon occurrences. Contributing factors are numerous and include injury to the saphenous nerve infrapatellar branches and/or histologic changes at the harvest site. The use of mini invasive harvesting technique decreases the risk of injury to the saphenous nerve infrapatellar branches while preserving the peritenon. The double-incision approach significantly reduces the mid-term incidence of anterior knee pain after ACL-reconstruction. Additionally, this technique markedly decreases the occurrence of sensory disorders and the extent of hypoesthesia. We thus advocate the use of a double-incision graft harvesting technique in ACL-reconstruction using a patellar-bone-tendon-bone transplant.

The influence of graft choice on isokinetic muscle strength 4-24 months after anterior cruciate ligament reconstruction

PURPOSE

Regaining adequate strength of the quadriceps and hamstrings after anterior cruciate ligament (ACL) reconstruction is important for maximizing functional performance. However, the outcome of muscle strength after either BPTB or hamstrings autograft is unclear given the plethora of published studies that report post-operative muscle strength. The purpose of this study was to systematically compare the muscle strength of patients who have undergone ACL reconstruction using either Bone Patellar Tendon Bone (BPTB) or Hamstrings (HST) autograft.

METHODS

The databases of MEDLINE, Cinahal and EMBASE were systematically searched for articles that report muscle strength outcome following ACL reconstruction. The quality of the studies was evaluated and a meta-analysis of the muscle strength outcomes was conducted on reported data.

RESULTS

Fourteen studies were included in this systematic review: eight Randomized Control Studies (RCT) and six non-Randomized Control Studies (non-RCT). A meta-analysis was performed involving eight of the included studies (4 RCTs & 3 non-RCTs). At 60°/s and 180°/s, patients with BPTB graft showed a greater deficit in extensor muscle strength and lower deficit in flexor muscle strength compared with patients with HST.

CONCLUSION

This systematic review of Level III evidence showed that isokinetic muscle strength deficits following ACL reconstruction are associated with the location of the donor site. These deficits appear to be unresolved up to 2 years after ACL reconstruction.

LEVEL OF EVIDENCE

III.

Biomechanical characterization of double-bundle femoral press-fit fixation techniques

PURPOSE

Press-fit fixation of patellar tendon bone anterior cruciate ligament autografts is an interesting technique because no hardware is necessary. To date, no biomechanical data exist describing an implant-free double-bundle press-fit procedure. The purpose of this study was to characterize the biomechanical properties of three double-bundle press-fit fixations.

METHODS

In a controlled laboratory study, the patellar-, quadriceps- and hamstring tendons of 10 human cadavers (age: 49.2 ± 18.5 years) were used. An inside out press-fit fixation with a knot in the semitendinosus and gracilis tendons (SG) combined with an additional bone block, with two quadriceps tendon bone block grafts (QU) was compared with press-fit fixation of two bone patellar tendon bone block (PT) grafts in 30 porcine femora. Constructs were cyclically stretched and then loaded until failure. Maximum load to failure, stiffness and elongation during failure testing and cyclical loading were investigated.

RESULTS

The maximum load to failure was 703 ± 136 N for SG fixation, 632 ± 130 N for QU and 656 ± 127 N for PT fixation. Stiffness of the constructs averaged 138 ± 26 N/mm for SG, 159 ± 74 N/mm for QU, and 154 ± 50 N/mm for PT fixation. Elongation during initial cyclical loading was 1.2 ± 1.4 mm for SG, 2.0 ± 1.4 mm for QU, and 1.0 ± 0.6 mm for PT (significantly larger for PT and QU between the first 5 cycles compared with cycles 15-20th, P < 0.01).

CONCLUSION

All investigated double-bundle fixation techniques were equal in terms of maximum load to failure, stiffness, and elongation. Unlike with single-bundle press-fit fixation techniques that have been published, no difference was observed between pure tendon combined with an additional bone block and tendon bone grafts. All techniques exhibited larger elongation during initial cyclical loading. All three press-fit fixation techniques that were investigated exhibit comparable biomechanical properties. Preconditioning of the constructs is critical.

Myositis ossificans as a complication of hamstring autograft harvest for open primary anterior and posterior cruciate ligament and posterolateral corner reconstruction

Post-traumatic myositis ossificans is a benign condition of heterotopic ossification of unknown aetiology which typically is related to trauma from a single blow or repeated episodes of microtrauma. A case of myositis ossificans that developed after hamstring autograft harvest for an open cruciate ligament and posterolateral corner reconstruction is described, a previously unrecognised complication of this procedure.

Aligned poly(L-lactic-co-e-caprolactone) electrospun microfibers and knitted structure: a novel composite scaffold for ligament tissue engineering

We developed a novel technique involving knitting and electrospinning to fabricate a composite scaffold for ligament tissue engineering. Knitted structures were coated with poly(L-lactic-co-e-caprolactone) (PLCL) and then placed onto a rotating cylinder and a PLCL solution was electrospun onto the structure. Highly aligned 2-microm-diameter microfibers covered the space between the stitches and adhered to the knitted scaffolds. The stress-strain tensile curves exhibited an initial toe region similar to the tensile behavior of ligaments. Composite scaffolds had an elastic modulus (150 +/- 14 MPa) similar to the modulus of human ligaments. Biological evaluation showed that cells proliferated on the composite scaffolds and they spontaneously orientated along the direction of microfiber alignment. The microfiber architecture also induced a high level of extracellular matrix secretion, which was characterized by immunostaining. We found that cells produced collagen type I and type III, two main components found in ligaments. After 14 days of culture, collagen type III started to form a fibrous network. We fabricated a composite scaffold having the mechanical properties of the knitted structure and the morphological properties of the aligned microfibers. It is difficult to seed a highly macroporous structure with cells, however the technique we developed enabled an easy cell seeding due to presence of the microfiber layer. Therefore, these scaffolds presented attractive properties for a future use in bioreactors for ligament tissue engineering.

Comparison of morphology, orientation, and migration of tendon derived fibroblasts and bone marrow stromal cells on electrochemically aligned collagen constructs

There are approximately 33 million injuries involving musculoskeletal tissues (including tendons and ligaments) every year in the United States. In certain cases the tendons and ligaments are damaged irreversibly and require replacements that possess the natural functional properties of these tissues. As a biomaterial, collagen has been a key ingredient in tissue engineering scaffolds. The application range of collagen in tissue engineering would be greatly broadened if the assembly process could be better controlled to facilitate the synthesis of dense, oriented tissue-like constructs. An electrochemical method has recently been developed in our laboratory to form highly oriented and densely packed collagen bundles with mechanical strength approaching that of tendons. However, there is limited information whether this electrochemically aligned collagen bundle (ELAC) presents advantages over randomly oriented bundles in terms of cell response. Therefore, the current study aimed to assess the biocompatibility of the collagen bundles in vitro, and compare tendon-derived fibroblasts (TDFs) and bone marrow stromal cells (MSCs) in terms of their ability to populate and migrate on the single and braided ELAC bundles. The results indicated that the ELAC was not cytotoxic; both cell types were able to populate and migrate on the ELAC bundles more efficiently than that observed for random collagen bundles. The braided ELAC constructs were efficiently populated by both TDFs and MSCs in vitro. Therefore, both TDFs and MSCs can be used with the ELAC bundles for tissue engineering purposes.

Comparison of potentials between stem cells isolated from human anterior cruciate ligament and bone marrow for ligament tissue engineering

We have previously isolated and identified stem cells from human anterior cruciate ligament (ACL). The purpose of this study was to evaluate the differences in proliferation, differentiation, and extracellular matrix (ECM) formation abilities between bone marrow stem cells (BMSCs) and ACL-derived stem cells (LSCs) from the same donors when cultured with different growth factors, including basic fibroblast growth factor (bFGF), epidermal growth factor, and transforming growth factor-beta 1 (TGF-beta1). Ligament tissues and bone marrow aspirate were obtained from patients undergoing total knee arthroplasty and ACL reconstruction surgeries. Proliferation, colony formation, and population doubling capacity as well as multilineage differentiation potentials of LSCs and BMSCs were compared. Gene expression and ECM production for ligament engineering were also evaluated. It was found that BMSCs possessed better osteogenic differentiation potential than LSCs, while similar adipogenic and chondrogenic differentiation abilities were observed. Proliferation rates of both LSCs and BMSCs were enhanced by bFGF and TGF-beta1. TGF-beta1 treatment significantly increased the expression of type I collagen, type III collagen, fibronectin, and alpha-smooth muscle actin in LSCs, but TGF-beta1 only upregulated type I collagen and tenascin-c in BMSCs. Protein quantification further confirmed the results of differential gene expression and suggested that LSCs and BMSCs increase ECM production upon TGF-beta1 treatment. In summary, in comparison with BMSCs, LSCs proliferate faster and maintain an undifferentiated state with bFGF treatment, whereas under TGF-beta1 treatment, LSCs upregulate major tendinous gene expression and produce a robust amount of ligament ECM protein, making LSCs a potential cell source in future applications of ACL tissue engineering.

Repair of insertional achilles tendinosis with a bone-quadriceps tendon graft

BACKGROUND

While conservative treatment may be successful in most cases, partial rupture at the calcaneal insertion point is a significant concern with insertional Achilles tendinopathy. We report on the outcomes of a surgical technique for Achilles tendon augmentation using a bone-tendon graft harvested from the knee extensor system.

MATERIALS AND METHODS

Our retrospective case series includes 25 surgical procedures performed in 24 patients, 19 males and five females, with a mean age of 47 (range, 30 to 59) years, 18 of whom were athletes. The mean followup period was 52 (range, 12 to 156) months. All patients underwent MRI examination prior to surgery which showed partial Achilles tendon rupture. The Achilles tendon was debrided through a posterolateral approach. The bone-quadriceps tendon graft was harvested, then the bone plug of the graft was inserted into a blind tunnel drilled into the calcaneus and fixed with an interference screw. The fibers of the quadriceps tendon were sutured to the residual part of the Achilles tendon with the foot at an angle of 90 degrees.

RESULTS

Patients were able to resume their sporting activity after an average of 6.7 months. At last followup examination, physical activity was scored 5.2 on the 10-point Tegner Scale; the mean AOFAS score was 98.4. MRI examination showed good graft integration 1 year postoperatively.

CONCLUSION

The bone-quadriceps tendon grafting technique was a good alternative for the insertional Achilles lesions with partial detachment which we felt required augmentation.

ACL graft migration under cyclic loading

Elongation and migration of ACL grafts will lead to a deterioration of the initial stability of ACL reconstructions. The graft migration has been sparsely investigated independently from the elongation of the graft-fixation complex. The hypothesis of this investigation was that cyclic tensile loads cause a measurable migration of the grafts. Three graft/fixation combinations were investigated in human femora (n = 7): human bone-patellar tendon grafts fixed with a biointerference screw (BPTG-IS) and free tendon grafts (porcine) fixed with either a Bio-TransFix pin (FTG-TF) or an Endobutton CL (FTG-EB). The grafts were fitted with tantalum markers. Then, the specimens were repetitively loaded (50-250 N, 800 cycles). The marker position was fluoroscopically determined at defined intervals and the migration calculated from the change in position relative to a fiducial marker within the bone. A migration of the grafts occurred in all three groups. The migration in the FTG-EB group was significantly larger than in the two other groups (P < 0.01). After 800 cycles, average migration was 0.3 (+/-0.2) mm in the BPTG-IS group, 0.7 (+/-0.4) mm FTG-TF group, 2.0 (+/-1.3) mm in the FTG-EB group. This migration might contribute to a loss of initial stability. Because the graft migration was dependent on the technique, the presented data might provide additional arguments for making the decision on the most appropriate graft/fixation combination.

Autologous patellar tendon and quadrupled hamstring grafts in anterior cruciate ligament reconstruction: a prospective randomized multicenter review of different fixation methods

ACL reconstruction with bone patellar tendon bone (BPTB) grafts has been shown to produce dependable results. Recently, reconstructions with double-looped semitendinosus gracilis (DLSG) grafts have become common. The prevailing opinion is that ACL reconstruction with patellar tendon graft produces a more stable knee with more anterior knee pain than DLSG grafts, while the functional results and knee scores are similar. The present study evaluates BPTB grafts fixed with metallic interference screws and DLSG grafts fixed with Bone Mulch Screw on the femur and WasherLoc fixation on the tibia. All else being the same, there is no difference in the outcome between the two grafts and fixation methods. This is a prospective randomized multicenter study. A total of 115 patients with isolated ACL ruptures were randomized to either reconstruction with BPTB grafts fixed with metal interference screws (58 patients) or DLSG grafts (57 patients) fixed with Bone Mulch Screws and WasherLoc Screws. Follow-up was at one and two years; the latter by an independent observer. At two years, one ACL revision had been performed in each group. Eight patients in the DLSG group and one in the BPTB group underwent meniscus surgery in the follow-up period (P = 0.014). Mean Lysholm score at the two year follow-up was 91 (SD +/- 10.3) in the DLSG group and also 91 (SD +/- 10.2) in the BPTB group. Mean KT-1000 at two years was 1.5 mm in the BPTB group and 1.8 mm in the DLSG group (n.s.). At two years, four patients in the BPTB group and three in the DLSG group had a Lachman test grade 2 or 3 (n.s.). More patients in the BPTB group had pain at the lower pole of the patella (P = 0.04). Peak flexion torque and total flexion work were lower in the DLSG group at one year (P = 0.003 and P = 0.000) and total flexion work also at two years (P = 0.05). BPTB ACL reconstruction fixed with interference screws and DLSG fixed with Bone Mulch Screws on the femur and WasherLoc Screws on the tibia produce satisfactory and nearly identical outcomes. Among our patients in the DLSG group, flexion strength was lower, and more patients underwent meniscus surgery in the follow-up period. The BPTB group has more anterior knee pain.

Hamstring donor-site block: evaluation of pain control after anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to evaluate the effectiveness of using a hamstring donor-site block in controlling postoperative pain levels after anterior cruciate ligament (ACL) reconstruction with autogenous hamstring graft.

METHODS

Over a 5-month period, 27 patients underwent ACL reconstruction with hamstring autograft. All patients received a preoperative femoral nerve block. Intraoperatively, these patients were randomly assigned to groups with and without a hamstring donor-site block. The block group received a 20-mL injection of 0.25% bupivacaine into the hamstring donor site through an arthroscopic shaver sleeve. Both groups received standard postoperative pain medications as needed. Postoperative pain scores were taken by use of a visual analog scale (VAS) and recorded immediately on arrival to the recovery room, at 1 hour after arrival, and at 2 hours after arrival.

RESULTS

There were 15 patients in the hamstring donor-site block group and 12 patients in the standard treatment group. For the block group, mean VAS scores were 3.20 +/- 2.54 on arrival, 2.80 +/- 1.61 at 1 hour, and 2.87 +/- 1.41 at 2 hours. For the standard treatment group, mean VAS scores were 5.50 +/- 1.62 on arrival, 6.08 +/- 1.56 at 1 hour, and 5.33 +/- 2.02 at 2 hours. The hamstring block group had statistically significantly lower mean VAS scores on arrival (P = .0118), at 1 hour (P = .0001), and at 2 hours (P = .0010). There were no complications in either group.

CONCLUSIONS

Injection of the hamstring donor site with local anesthetic through an arthroscopic shaver sleeve showed a statistically significant improvement in postoperative pain levels in patients undergoing autogenous hamstring ACL reconstruction.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Factors affecting the longevity and strength in an in vitro model of the bone-ligament interface

The interfaces between musculoskeletal tissues with contrasting moduli are morphologically and biochemically adapted to allow the transmission of force with minimal injury. Current methods of tissue engineering ligaments and tendons do not include the interface and this may limit the future clinical success of engineered musculoskeletal tissues. This study aimed to use solid brushite cement anchors to engineer intact ligaments from bone-to-bone, creating a functional musculoskeletal interface in vitro. We show here that modifying anchor shape and cement composition can alter both the longevity and the strength of an in vitro model of the bone-ligament interface: with values reaching 23 days and 21.6 kPa, respectively. These results validate the use of brushite bone cement to engineer the bone-ligament interface in vitro and raise the potential for future use in ligament replacement surgery.

A comparison of the quasi-static mechanical and non-linear viscoelastic properties of the human semitendinosus and gracilis tendons

BACKGROUND

Over 50-% of anterior cruciate ligament reconstructions are performed using semitendinosus and gracilis tendon autografts. Despite their increased use, there remains little quantitative data on their mechanical behavior. Therefore, the objective of this study was to investigate the quasi-static mechanical and non-linear viscoelastic properties of human semitendinosus and gracilis tendons, as well as the variation of these properties along their length.

METHODS

Specimens were subjected to a series of uniaxial tensile tests: 1-h static stress-relaxation test, 30 cycle cyclic stress-relaxation test and load to failure test. To describe the non-linear viscoelastic behavior, the quasi-linear viscoelastic theory was utilized to model data from the static stress-relaxation experiment.

FINDINGS

The constants describing the viscoelastic behavior were similar between the proximal and distal halves of the gracilis tendon. The proximal half of the semitendinosus tendon, however, had a greater viscous response than its distal half, which was also significantly higher than the proximal gracilis tendon. In terms of the quasi-static mechanical properties, the properties were similar between the proximal and distal halves of the semitendinosus tendon. However, the distal gracilis tendon showed a significantly higher tangent modulus and ultimate stress compared to its proximal half, which was also significantly higher than the distal semitendinosus tendon.

INTERPRETATION

The results of this study demonstrate differences between the semitendinosus and gracilis tendons in terms of their quasi-static mechanical and non-linear viscoelastic properties. These results are important for establishing surgical preconditioning protocols and graft selection.

Design and characterization of a biodegradable composite scaffold for ligament tissue engineering

Herein we report on the development and characterization of a biodegradable composite scaffold for ligament tissue engineering based on the fundamental morphological features of the native ligament. An aligned fibrous component was used to mimic the fibrous collagen network and a hydrogel component to mimic the proteoglycan-water matrix of the ligament. The composite scaffold was constructed from cell-adherent, base-etched, electrospun poly(epsilon-caprolactone-co-D,L-lactide) (PCLDLLA) fibers embedded in a noncell-adherent photocrosslinked N-methacrylated glycol chitosan (MGC) hydrogel seeded with primary ligament fibroblasts. Base etching improved cellular adhesion to the PCLDLLA material. Cells within the MGC hydrogel remained viable (72 +/- 4%) during the 4-week culture period. Immunohistochemistry staining revealed ligament ECM markers collagen type I, collagen type III, and decorin organizing and accumulating along the PCLDLLA fibers within the composite scaffolds. On the basis of these results, it was determined that the composite scaffold design was a viable alternative to the current approaches used for ligament tissue engineering and merits further study.

Knee flexor strength after ACL reconstruction: comparison between hamstring autograft, tibialis anterior allograft, and non-injured controls

Hamstring muscle group dysfunction following anterior cruciate ligament reconstruction (ACL) using a semitendinosus-gracilis autograft is a growing concern. This study compared the mean peak isometric knee flexor torque of the following three groups: subjects 2 years following ACL reconstruction using semitendinosus-gracilis autografts (Group 1), subjects 2 years following ACL reconstruction using tibialis anterior allografts (Group 2), and a non-injured, activity-level-matched control group (Group 3). We hypothesized that Group 1 would have greater mean involved lower extremity peak isometric knee flexor torque deficits than the other groups. Handheld dynamometry with subjects in prone and the test knee at 90 degrees flexion was used to determine bilateral peak isometric knee flexor torque. Group 1 (86.4 +/- 11) and Group 2 (80.5 +/- 13) had similar 2000 IKDC Subjective Knee Evaluation Form scores (P = NS). Group 1 had a mean involved lower extremity peak isometric knee flexor torque deficit of -17.0 +/- 14 Nm. Group 2 had a mean involved lower extremity peak isometric knee flexor torque deficit of -0.8 +/- 9 Nm. Group 3 (control) had a mean left and right lower extremity peak isometric knee flexor torque difference of -0.7 +/- 14 Nm. Group 1 had decreased involved lower extremity peak isometric knee flexor torque compared to Groups 2 and 3 (two-way ANOVA; group x side interaction P < 0.05, Tukey HSD = 0.008). Long-term knee flexor strength deficits exist following hamstring autograft use for ACL reconstruction that does not occur when a tibialis anterior allograft is used. Early identification of impaired knee flexor strength among this group and modified rehabilitation may reduce these deficits. Adding quantitative biomechanical testing of sprinting and sudden directional change movements to the standard physical therapy evaluation will better elucidate the clinical and functional significance of the observed knee flexor strength impairments and aid in determining sport specific activity training readiness.

Rehabilitation results following anterior cruciate ligament reconstruction using a hard brace compared to a fluid-filled soft brace

The purpose of this study was to compare the clinical outcomes of rehabilitation after ACL reconstruction using a water-filled soft brace to those using a hard brace. The method used in this study was a prospective randomised clinical trial including 36 patients wearing a hard brace and 37 patients wearing a water-filled soft brace for 6 weeks after surgery. Preoperative and postoperative (seven examinations) clinical evaluation within a follow-up period of 1 year including effusion status, swelling and range of motion (ROM), IKDC 2000, KT1000 Arthrometer, Lysholm knee scoring scale and Tegner activity score. Mean values are presented with standard deviations. Data was analysed using descriptive statistics and Student's t-test for unpaired samples. Significantly less effusion was found in the soft brace group from 5 days (p=0.002) to 12 weeks (p<0.024) postoperative. Hard brace patients presented with significantly more extension deficit from 5 days (p=0.036) to 12 months (p=0.014) postoperative but no significant difference was detected in complete ROM, laxity or thigh atrophy at any follow-up examination. Patients treated with a soft brace had significantly higher IKDC subjective ratings at 6 weeks (p=0.02) up to 12 months after operation (p=0.002) and rated significantly higher in Tegner activity score (p=0.004) and Lysholm knee scoring scale (p=0.006) 6 and 12 months (p<0.001 for both scores) postoperatively. The water-filled soft brace was superior regarding effusion, swelling, extension deficit and patient-measured midterm outcome. The soft brace presents a safe, easy-to-use and effective alternative to the hard brace.

Does the graft source really matter in the outcome of patients undergoing anterior cruciate ligament reconstruction? An evaluation of autograft versus allograft reconstruction results: a systematic review

BACKGROUND

Despite the large number of anterior cruciate ligament reconstructions performed each year, there remains a significant controversy regarding the effect of the graft source on the functional outcome of patients.

HYPOTHESIS

There is no difference in outcomes of autograft versus allograft anterior cruciate ligament reconstructions.

STUDY DESIGN

Systematic review.

METHODS

The authors systematically identified prospective studies (Oxford level of evidence I or II only) that included autograft patients, allograft patients, or both. Objective outcomes that were reported were meta-analyzed; this included pivot-shift results, KT-1000 arthrometer results, International Knee Documentation Committee (IKDC) scores, Lysholm Scores, graft failures, and postoperative complications. Two statistical analyses were performed. First a primary statistical analysis was performed comparing pooled autograft data (bone-patellar-tendon bone and hamstrings combined) and pooled allograft data (bone-patellar-tendon bone and hamstrings combined). To have a more comprehensive understanding of the differences between each specific graft source, a secondary analysis was performed without pooling the data; this directly compared the 4 types of graft sources that were studied.

RESULTS

Over 400 scientific manuscripts were initially reviewed; 31 manuscripts fulfilled all of the search criteria. There were very few statistically significant differences between autograft and allograft tissue. The KT-1000 arthrometer laxity testing revealed a mean of 1.4 +/- 0.2 mm (weighted mean +/- standard error of the mean) for the allograft group compared with 1.8 +/- 0.1 mm for the autograft group (t = 2.40; P <.02). However, this difference was only for the mean score; there was no statistical significance when considering KT-1000 arthrometer measurements of greater than 3 or 5 mm. The percentage of patients receiving a final IKDC score of "A" (normal knee) was statistically significant for allograft tissue (43.9% +/- 5.5%) versus autograft tissue (28.2% +/- 1.0%) reconstructions. There was no statistically significant difference between the percentages of IKDC scores of A or B for patients receiving pooled allograft (82.9% +/- 4.2%) versus pooled autograft (87.2% +/- 0.9%) anterior cruciate ligament reconstruction (t = 1.01; P > .1). The graft failure rate was 4.7 +/- 0.5 per 100 for autograft reconstructions and 8.2 +/- 2.1 per 100 allograft reconstructions; although this may represent a trend, it is not statistically significant (t = 1.49; P > .1). The complication rate was slightly higher for autograft reconstructions at 3.5 +/- 0.4 complications per 100 autograft reconstructions compared with 2.4 +/- 1.1 complications per 100 allograft reconstructions, but not significant (t = 1.41; P > .1).

CONCLUSION

After a comprehensive examination and statistical analysis of the modern literature, the authors could not identify an individual graft source that was clearly superior to the other graft sources. This led them to believe that, with currently available data, the graft source has a minimal effect on the outcome of patients undergoing anterior cruciate ligament reconstruction.

The role of anterior cruciate ligament reconstruction in the older patients, 55 years or above

Anterior cruciate ligament (ACL) deficiency can result in symptomatic functional instability of the knee regardless of the patient's age. We reviewed a single surgeon database of 908 ACL reconstructions carried out in the last 20 years for symptomatic instability. 14 patients were identified who were 55 years or above at surgery (mean: 60 years, range 55-75 years). Patients were evaluated clinically and with clinical outcome scoring and KT-1000 arthrometry assessment. 12 patients (86%) were available to attend for follow-up at a mean 9 years after ACL reconstruction. The median pre-injury Tegner score was 5.5 (range 1-7) and the median pre-operative Lysholm score was 33 (range 15-67). Initially, one patient had a good result but subsequently the patient undergone total knee replacement 5 years after ACL reconstruction. For the remainder, at the most recent review, the median Lysholm score had improved to 79 (range 43-100, P < 0.05) although it had deteriorated from the maximum achieved post-op score of 85.5 (range 53-100, P < 0.05); and the Tegner score had declined to 3 (range 1-5, P < 0.05). KT-1000 testing demonstrated a mean side-to-side difference improvement in laxity from 4.6 +/- 1.3 mm (range 3-7) to 1.5 +/- 1.2 mm (range 0-4, P < 0.05) and >2 mm difference in only one knee (for which it was known that the graft had failed at 11 years after ACL reconstruction). At review, the same knee was the only one that demonstrated a pivot shift. ACL reconstruction with autograft in the above-55 patient with minimal osteoarthritis is a safe procedure that returns stability to the knee and permits a return to a reasonable level of activity.

Anatomy of normal human anterior cruciate ligament attachments evaluated by divided small bundles

BACKGROUND

Double-bundle anterior cruciate ligament (ACL) reconstruction has several potential advantages over single-bundle reconstruction with hamstring tendons. However, there are still controversies regarding tunnel placement in tibial and femoral attachments.

HYPOTHESIS

The macroscopically normal ACL consists of small bundles about 1 mm in diameter. Detailed observation of the divided smaller bundles will achieve better understanding of the tunnel placement in anatomic ACL reconstruction.

STUDY DESIGN

Descriptive laboratory study.

METHODS

This study used 20 cadaveric knees. The ACL was divided into anteromedial and posterolateral bundles, then separated into 10 small bundles of 2-mm diameters, with preservation of their attachment sites marked with color markers. The positional relationship between the femoral and tibial attachments of each small bundle was investigated.

RESULTS

A layered positional correlation of small bundles was found between the tibial and femoral attachments. Small bundles aligned in the anterior-posterior direction in the tibia corresponded to the bundles aligned in a high-low direction in the femur in flexion. The femoral attachment pattern was relatively similar in each specimen; however, the tibial attachment showed 2 patterns: an oblique type (12 of 20) and a transverse type (8 of 20). The posterior portion of the posterolateral bundle was separately attached to the medial and lateral portions of the tibial attachment. There was no fibrous insertion in the center of the posterior portion of the ACL tibial attachment in any specimen. In this bare area, there was fat tissue and vascular bundles.

CONCLUSION

Small bundles constituting the ACL showed a relatively layered arrangement between 2 attachments. The tibial attachment showed 2 patterns of oblique and transverse types, and the vascular bundles were located in the center of the posterolateral bundle.

CLINICAL RELEVANCE

The results of this study of the normal ACL will provide insights for surgeons when placing grafts during anatomic ACL reconstruction.

Electromechanical delay of the knee flexor muscles is impaired after harvesting hamstring tendons for anterior cruciate ligament reconstruction

BACKGROUND

Changes in electromechanical delay during muscle activation are expected when there are substantial alterations in the structural properties of the musculotendinous tissue. In anterior cruciate ligament reconstruction, specific tendons are being harvested for grafts. Thus, there is an associated scar tissue development at the tendon that may affect the corresponding electromechanical delay.

PURPOSE

This study was conducted to investigate whether harvesting of semitendinosus and gracilis tendons for anterior cruciate ligament reconstruction will affect the electromechanical delay of the knee flexors.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

The authors evaluated 12 patients with anterior cruciate ligament reconstruction with a semitendinosus and gracilis autograft, 2 years after the reconstruction, and 12 healthy controls. Each participant performed 4 maximally explosive isometric contractions with a 1-minute break between contractions. The surface electromyographic activity of the biceps femoris and the semitendinosus was recorded from both legs during the contractions.

RESULTS

The statistical comparisons revealed significant increases of the electromechanical delay of the anterior cruciate ligament-reconstructed knee for both investigated muscles. Specifically, the electromechanical delay values were increased for both the biceps femoris (P = .029) and the semitendinosus (P = .005) of the reconstructed knee when compared with the intact knee. Comparing the anterior cruciate ligament-reconstructed knee against healthy controls revealed similar significant differences for both muscles (semitendinosus, P = .011; biceps femoris, P = .024).

CONCLUSION

The results showed that harvesting the semitendinosus and gracilis tendons for anterior cruciate ligament reconstruction significantly increased the electromechanical delay of the knee flexors. Increased hamstring electromechanical delay might impair knee safety and performance by modifying the transfer time of muscle tension to the tibia and therefore affecting muscle response during sudden movements in athletic activities. However, further investigation is required to identify whether the increased electromechanical delay of the hamstrings can actually influence optimal sports performance and increase the risk for knee injury in athletes with anterior cruciate ligament reconstructions.

[Possibilities and limits in tissue engineering of the anterior cruciate ligament]

Although current concepts of cruciate ligament reconstruction using tendon transplants provide midterm knee joint stabilization, a single-bundle or double-bundle tendon cannot adequately restore the complex three-dimensional structure of the anterior cruciate ligament. Therefore, researchers are attempting to develop alternatives using tissue engineering technology. The basic principle includes seeding of suitable cells on a resorbable carrier construct, in vitro biological and mechanical stimulation to generate a ligament-like extracellular matrix, and subsequent implantation as a cruciate ligament bioprosthesis. Several natural and synthetic materials have proven to be suitable as cell carriers; however, most of these exhibit inadequate tensile strength as well as minor fatigue properties, making an additional load carrier necessary. In principle, research has shown that tissue engineering technology is capable of generating a construct with a ligament-like extracellular matrix. However, the step from basic research to clinical application has not yet been taken.

Isolation and characterization of mesenchymal stromal cells from human anterior cruciate ligament

BACKGROUND

The anterior cruciate ligament (ACL) is one of the most commonly injured ligaments of the knee. Because the torn ACL is always discarded during ACL reconstruction, it may be a potential source for isolating mesenchymal stromal cells (MSC).

METHODS

To characterize MSC from human ACL, cells were enzymatically released from the ACL of adult human donors and seeded in plastic dishes with serial passages at confluence. At different passages, ACL-derived cells were subjected to in vitro assays to investigate their multilineage potential. Upon treatment, the phenotypes of the cell cultures were analyzed by histo- and immunohistochemistry and semi-quantitative reverse transcription-polymerase chain reaction for the expression of lineage-specific genes.

RESULTS

Six independent cell lines from individual donors showed diversity in multilineage potential. Interestingly, five of the six lines displayed adipogenic potential, four had osteogenic and adipogenic potential, and only one cell line was tripotent. Both bone marrow (BM)- and ACL-derived MSC expressed marker genes for ligament fibroblasts, whereas the mRNA levels of collagen I and III were more abundant in ACL-derived MSC.

DISCUSSION

Our study demonstrates that human MSC can be isolated from ACL with diversity in the potential to form bone, fat and cartilage and an increase as compared to BM MSC, in the potential to form ligament fibroblasts.

Anterior cruciate ligament graft reconstruction: clinical, technical, and imaging overview

The anterior cruciate ligament (ACL) is one of the most frequently torn ligaments of the knee. With more than 100,000 ACL reconstructions performed yearly in the United States, evaluation of ACL grafts with magnetic resonance imaging is a common occurrence in daily clinical practice. Anterior cruciate ligament reconstructions vary from single bundle, double bundle, selective bundle, and physeal-sparing techniques. Complications of ACL graft reconstructions include graft tears, graft laxity, arthrofibrosis, and hardware failure or migration. This article offers a comprehensive review of ACL reconstruction for the consulting radiologist.

Ankle morbidity after autogenous Achilles tendon harvesting for anterior cruciate ligament reconstruction

Although several alternative autografts with reduced morbidity of harvest site have been introduced, no donor site is free of morbidity concerns. The authors report on ankle status after autogenous Achilles tendon harvesting with a minimum 10-year follow-up. From October 1994 to October 1996, a consecutive series of 47 ankles underwent harvesting of the medial third or half of the ipsilateral autogenous Achilles tendon for primary anterior cruciate ligament reconstruction. Donor site statuses were evaluated using a modified Thermann's scale. Postoperative isokinetic muscle strength testing was performed, and magnetic resonance images of donor sites were available for selected patients. Thirty-three ankles in the 32 patients were followed for more than 10 years. There were 27 men (84%) and 5 women (16%) with a mean age of 31 years (range 16-52 years) at the time of surgery. The mean duration of follow-up was 12 years and 1 month (range 10 years and 5 months to 13 years and 4 months). Mean postoperative modified Thermann's scale score was 87 (range 45-95; SD 14.3). Twenty-five (76%) ankles achieved very good or good results. A slight decrease in calf circumference <1 cm was seen in the ten ankles, 1-2 cm in the four ankles. Nine ankles were mildly hypersensitive to meteorological changes. Peak torque of ankle plantar flexion was slightly lower on the index limb at both velocities in nine selected patients who carried out performance tests. However, there were no significant differences (5.2% at 30 degrees /s and 2.7% at 120 degrees /s, P = n.s. and P = n.s.). Of the 12 available follow-up magnetic resonance images, the average cross-sectional area of the remaining tendon was 82.01 mm(2) (range 69.05-107.35; SD 10.3), and their average thickness was 7.4 mm (range 6-10.35; SD 1.1). After a minimum 10-year follow-up, the harvesting of autogenous Achilles tendons was not found to significantly jeopardize ankle status. However, it also could not be independent of donor morbidity as an alternative. The level of evidence was retrospective level IV, as a therapeutic study.

Comparable results between lateralized single- and double-bundle ACL reconstructions

Patellar tendon autografts are not suitable for multibundle ACL reconstruction, a procedure that reportedly enhances postoperative knee stability. Biomechanical studies recommend lateral placement of the femoral tunnel for single-bundle reconstruction to improve postoperative knee kinematics. We asked whether a lateralized single-bundle patellar tendon graft (LSBP) would provide good short-term results of ACL reconstruction comparable to double-bundle hamstring tendon grafts (DBH). We prospectively followed 144 patients with unilateral ACL rupture treated with either LSBP or DBH in a nonrandomized fashion. Twenty-four female and 31 male patients with LSBP and 44 female and 26 male patients with DBH were followed for a minimum of 24 months (average, 38 months; range, 24-56 months). The patients with LSBP recovered knee extension better at 1 month compared with the patients with DBH, but extension was similar after 3 months. We observed no differences in the side-to-side difference of KT1000 measurement, pivot shift test, or anterior drawer test between LSBP and DBH. Although better recovery of hamstring strength in LSBP and better recovery of quadriceps strength in DBH were observed in the early postoperative period, these differences disappeared after 12 months. There was no difference in International Knee Documentation Committee objective evaluation between LSBP and DBH at the final followup.

LEVEL OF EVIDENCE

Level II, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.