Anterior cruciate ligament repair - past, present and future

The "Motionless Gastrocnemius": A Reliable Sign for Safe Graft Harvesting

Difficulties in graft harvesting of the hamstring have been the topic of many studies. These difficulties are related to the aponeurotic or fibrous attachments of the hamstrings with the medial head of the gastrocnemius muscle, soleus muscle, and leg fascia. Freeing the graft from these attachments is important because insufficient release prior to stripper insertion can lead to premature transection or amputation. We describe a reliable intraoperative physical examination sign to help understand the sufficient amount by which a tendon graft needs to be released prior to stripper insertion. The presence of the motionless gastrocnemius ("motionless gastroc") phenomenon is used in our clinic as a sign that the grafts have been sufficiently freed and that a tendon stripper can be used without fear of transection or graft amputation.

Histological and cellular evaluation of anterior cruciate ligament

BACKGROUND

We hypothesized that the torn anterior cruciate ligament (ACL) demonstrates a great healing response after initial trauma and has competent cells leading to the healing but differs in its response based on the type of tear and duration of injury. This study aimed to evaluate the histological and cellular responses to the injured ACL.

METHODS

Fifty-two tissue samples from the ACL were harvested from patients undergoing arthroscopy. Detailed histological and cellular examinations were performed for ligament angiogenesis, fibrocytes, and synovial tissue infiltration. We compared the cellular response to injury in partially and completely ruptured ACLs. The duration of ACL injury and its response to cellular characteristics were also examined. Immunohistochemical studies using cluster of differentiation 34 (CD34) staining was used to evaluate endothelial cells and fibrocytes.

RESULTS

We found a significantly higher density of synovial and ligament angiogenesis and fibrocytes at the torn end of ACL (Mann-Whitney, P < 0.050). Numerous fibrocytes were identified in complete ACL tears versus partial tears (Mann-Whitney = 0.020). Increased cellular proliferation was identified at the ruptured end of ACL remnant (Kruskal-Wallis, P < 0.050). The cellular proliferation of ruptured ACL decreased after 12 months.

CONCLUSIONS

Based on our findings of the time-dependent decrease in the cellular response at the torn ends of the ACL, we recommend early intervention, preservation of the ACL remnant, and primary ACL repair or augmented reconstruction.

Good to Excellent Functional Short-Term Outcome and Low Revision Rates Following Primary Anterior Cruciate Ligament Repair Using Suture Augmentation

The aim of this study was to evaluate the functional outcome of primary anterior cruciate ligament (ACL) repair using suture augmentation (SA) in 93 consecutive patients (67 female) with a minimum follow-up of 12 months. Patients’ outcomes were determined using International Knee Documentation Committee (IKDC) score, Lysholm score (LS) and Tegner score (TS). Knee-laxity was assessed using the KT-1000 arthrometer. Eighty-eight patients (67 female, mean age 42 years ± standard deviation (SD) 13) were available for follow-up after a mean time of 21 months (range 12–39). Three patients (3%) underwent revision surgery and were excluded from functional analysis. The mean IKDC score was 87.4 ± 11, mean LS was 92.6 ± 11, mean pre-traumatic TS was 6 ± 2 and mean postoperative TS was 6 ± 2, with a mean difference (TS_Diff) of 1 ± 1. The interval from injury to surgery had no significant impact on the postoperative IKDC (p = 0.228), LS (p = 0.377) and TS_Diff (p = 0.572). Patients’ age (>40 years), BMI (>30) and coexisting ligament or meniscal injuries did not seem to influence postoperative functional results. Primary ACL repair using SA provides good to excellent functional outcomes with a low probability of revision surgery at a minimum of 12 months.

Investigating Commercial Filaments for 3D Printing of Stiff and Elastic Constructs with Ligament-Like Mechanics

The current gold standard technique for treatment of anterior cruciate ligament (ACL) injury is reconstruction with autograft. These treatments have a relatively high failure and re-tear rate. To overcome this, tissue engineering and additive manufacturing are being used to explore the potential of 3D scaffolds as autograft substitutes. However, mechanically optimal polymers for this have yet to be identified. Here, we use 3D printing technology and various materials with the aim of fabricating constructs better matching the mechanical properties of the native ACL. A fused deposition modeling (FDM) 3D printer was used to microfabricate dog bone-shaped specimens from six different polymers—PLA, PETG, Lay FOMM 60, NinjaFlex, NinjaFlex-SemiFlex, and FlexiFil—at three different raster angles. The tensile mechanical properties of these polymers were determined from stress–strain curves. Our results indicate that no single material came close enough to successfully match reported mechanical properties of the native ACL. However, PLA and PETG had similar ultimate tensile strengths. Lay FOMM 60 displayed a percentage strain at failure similar to reported values for native ACL. Furthermore, raster angle had a significant impact on some mechanical properties for all of the materials except for FlexiFil. We therefore conclude that while none of these materials alone is optimal for mimicking ACL mechanical properties, there may be potential for creating a 3D-printed composite constructs to match ACL mechanical properties. Further investigations involving co-printing of stiff and elastomeric materials must be explored.

A Review on Finite Element Modeling and Simulation of the Anterior Cruciate Ligament Reconstruction

The anterior cruciate ligament (ACL) constitutes one of the most important stabilizing tissues of the knee joint whose rapture is very prevalent. ACL reconstruction (ACLR) from a graft is a surgery which yields the best outcome. Taking into account the complicated nature of this operation and the high cost of experiments, finite element (FE) simulations can become a valuable tool for evaluating the surgery in a pre-clinical setting. The present study summarizes, for the first time, the current advancement in ACLR in both clinical and computational level. It also emphasizes on the material modeling and properties of the most popular grafts as well as modeling of different surgery techniques. It can be concluded that more effort is needed to be put toward more realistic simulation of the surgery, including also the use of two bundles for graft representation, graft pretension and artificial grafts. Furthermore, muscles and synovial fluid need to be included, while patellofemoral joint is an important bone that is rarely used. More realistic models are also required for soft tissues, as most articles used isotropic linear elastic models and springs. In summary, accurate and realistic FE analysis in conjunction with multidisciplinary collaboration could contribute to ACLR improvement provided that several important aspects are carefully considered.

Radiographic and Symptomatic Knee Osteoarthritis 32 to 37 Years After Acute Anterior Cruciate Ligament Rupture

BACKGROUND

The long-term prevalence of knee osteoarthritis (OA) after anterior cruciate ligament (ACL) injury is unknown, especially in patients without a history of ACL surgery.

PURPOSE

To (1) describe the prevalence of radiographic OA, symptomatic OA, and knee replacement surgery 32 to 37 years after acute ACL injury and to (2) compare the prevalence of radiographic OA, symptomatic OA, and knee symptoms between patients allocated to early ACL surgery or no ACL surgery and patients who crossed over to ACL surgery.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Participants aged 15 to 40 years at the time of ACL injury were allocated to surgical (augmented or nonaugmented ACL repair) or nonsurgical ACL treatment within 14 days of injury. At 32 to 37 years after the initial injury, 153 participants were followed up with plain weightbearing radiographs and completed 4 subscales from the Knee injury and Osteoarthritis Outcome Score (KOOS). Radiographic OA was defined as Kellgren and Lawrence grade 2 or higher. Symptomatic OA was defined as radiographic OA plus knee symptoms measured with the KOOS.

RESULTS

Participants allocated to ACL surgery (n = 64) underwent surgery at a mean ± SD of 5 ± 4 days (range, 0-11 days) after injury. Of the 89 participants allocated to no ACL surgery, 53 remained nonsurgically treated, 27 had ACL surgery within 2 years, and 9 had ACL surgery between 3 and 21 years after injury. In the total sample, 95 participants (62%) had radiographic tibiofemoral OA, including 11 (7%) who had knee replacement. The prevalence of radiographic tibiofemoral OA was lower in the group allocated to ACL surgery compared with the group who never had ACL surgery (50% vs 75%; P = .005). The prevalence of symptomatic OA (50% in the total sample) and patellofemoral radiographic OA (35% in the total sample) was similar between groups.

CONCLUSION

Patients allocated to early ACL surgery, performed a mean 5 days after injury, had a lower prevalence of tibiofemoral radiographic OA at 32 to 37 years after injury compared with patients who never had ACL surgery. The prevalences of symptomatic OA, radiographic patellofemoral OA, and knee symptoms were similar irrespective of ACL treatment. Overall, the prevalence of OA after ACL injury was high.

REGISTRATION

NCT03182647 (ClinicalTrials.gov identifier).

Effects of autologous adipose-derived regenerative stem cells administered at the time of anterior cruciate ligament reconstruction on knee function and graft healing

PURPOSE

To compare the healing and clinical outcomes of anterior cruciate ligament (ACL) reconstruction between patients with or without intraoperative administration of adipose-derived regenerative stem cells (ADRC).

METHODS

Between 2013 and 2014, the outcomes of 20 soccer players undergoing ACL reconstruction using bone-patellar tendon-bone autograft infiltrated with ADRC at the end of the procedure were compared to a historical, matched cohort of 19 soccer players undergoing the same procedure without ADRC. Outcomes were obtained at baseline, and 6 and 12 months postop for IKDC (International Knee Documentation Committee), Lysholm, and Lequesne, and at 2, 4, 6, and 12 months postop for VAS (visual analogue scale) for pain and graft maturation to evaluate the ligamentization process (magnetic resonance imaging (MRI)-based).

RESULTS

Both groups significantly improved the IKDC (p < 0.001 in both groups), Lysholm (p < 0.001 in both groups), Lequesne index (p < 0.001 in both groups), VAS for pain (p = 0.002 for the ADRC and p < 0.001 for the control group), and MRI scores (p < 0.001 in both groups) in the 12 months postop compared to baseline scores. However, there were no significant differences in the improvement of the outcomes between groups across time (p > 0.05). All patients returned to sports after surgery, but 8 (40%) patients in the ADRC and 13 (68.4%) patients in the control group had lower Tegner activity score at 12 months postop.

CONCLUSIONS

Patients receiving ADRC at the time of ACL reconstruction significantly improved knee function and healing/maturation of the graft at 12 months. However, this improvement was not statistically significant compared to a control group undergoing ACL reconstruction alone.

Identifying potential patient-specific predictors for anterior cruciate ligament reconstruction outcome - a diagnostic in vitro tissue remodeling platform

Purpose

Upon anterior cruciate ligament (ACL) rupture, reconstruction is often required, with the hamstring tendon autograft as most widely used treatment. Post-operative autograft remodeling enhances graft rupture risk, which occurs in up to 10% of the patient population, increasing up to 30% of patients aged under 20 years. Therefore, this research aimed to identify potential biological predictors for graft rupture, derived from patient-specific tissue remodeling-related cell properties in an in vitro micro-tissue platform.

Methods

Hamstring tendon-derived cells were obtained from remnant autograft tissue after ACL reconstructions (36 patients, aged 12–55 years), and seeded in collagen I gels on a micro-tissue platform. Micro-tissue compaction over time – induced by altering the boundary constraints – was monitored. Pro-collagen I expression was assessed using ELISA, and protein expression of tenomodulin and α-smooth muscle actin were measured using Western blot. Expression and activity of matrix metalloproteinase 2 were determined using gelatin zymography.

Results

Only micro-tissues corresponding to younger patients occasionally released themselves from the constraining posts. Pro-collagen I expression was significantly higher in younger patients. Differences in α-smooth muscle actin and tenomodulin expression between patients were found, but these were age-independent. Active matrix metalloproteinase 2 expression was slightly more abundant in younger patients.

Conclusions

The presented micro-tissue platform exposed patient-specific remodeling-related differences between tendon-derived cells, with the micro-tissues that released from constraining posts and pro-collagen I expression best reflecting the clinical age-dependency of graft rupture. These properties can be the starting point in the quest for potential predictors for identifying individual patients at risk for graft rupture.

Does an Accelerated Program Give Equivalent Results in Both Elite Athletes and Nonathletes?

CONTEXT

Although many researchers have investigated the functional outcomes of different accelerated rehabilitation programs after anterior cruciate ligament reconstruction (ACLR), the functional results of the same accelerated rehabilitation program following ACLR applied for both elite athletes and nonathletes have not yet been investigated.

OBJECTIVE

To examine the effects of the same accelerated anterior cruciate ligament rehabilitation program on pain and functionality of elite athletes and nonathletes.

DESIGN

Prospective preintervention-postintervention design.

SETTING

Physiotherapy department.

PARTICIPANTS

Fifteen elite athletes and 15 nonathletes who underwent unilateral ACLR with autologous hamstring tendon graft.

INTERVENTION

All participants received the same protocol for 6 weeks (5 sessions in a week).

MAIN OUTCOME MEASURES

Primary measurements were pain intensity, which was measured by visual analog scale, range of motion measurement using universal goniometer, and functionality, which was detected by Lysholm score. Secondary measurements were short form-36 and Beck Depression Inventory.

RESULTS

Higher Lysholm (P = .001) and Beck Depression Inventory (P = .03) scores were observed in the elite athlete group, and higher pain (P = .001) was observed in the nonathlete group at baseline assessments. Significant improvement detected for pain (P < .05), knee flexion range (P < .05), Lysholm score (P < .05), and Beck Depression Inventory (P < .05) compared with preintervention for both groups. Finally, after comparing the mean change values, the nonathlete group displayed greater decrease in pain level (P = .01) and participants in the elite athlete group further showed a greater decrease in depression level (P = .001).

CONCLUSIONS

This study found that the same accelerated rehabilitation protocol provides significant improvements for pain, functionality, and depression in both elite athletes and nonathletes after ACLR. Clinicians should consider our results when applying an anterior cruciate ligament rehabilitation program for nonathlete groups.

Bioaugmentation in the surgical treatment of anterior cruciate ligament injuries: A review of current concepts and emerging techniques

Injuries involving the anterior cruciate ligament are among the most common athletic injuries, and are the most common involving the knee. The anterior cruciate ligament is a key translational and rotational stabilizer of the knee joint during pivoting and cutting activities. Traditionally, surgical intervention in the form of anterior cruciate ligament reconstruction has been recommended for those who sustain an anterior cruciate ligament rupture and wish to remain active and return to sport. The intra-articular environment of the anterior cruciate ligament makes achieving successful healing following repair challenging. Historically, results following repair were poor, and anterior cruciate ligament reconstruction emerged as the gold-standard for treatment. While earlier literature reported high rates of return to play, the results of more recent studies with longer follow-up have suggested that anterior cruciate ligament reconstruction may not be as successful as once thought: fewer athletes are able to return to sport at their preinjury level, and many still go on to develop osteoarthritis of the knee at a relatively younger age. The four principles of tissue engineering (cells, growth factors, scaffolds, and mechanical stimuli) combined in various methods of bioaugmentation have been increasingly explored in an effort to improve outcomes following surgical treatment of anterior cruciate ligament injuries. Newer technologies have also led to the re-emergence of anterior cruciate ligament repair as an option for select patients. The different biological challenges associated with anterior cruciate ligament repair and reconstruction each present unique opportunities for targeted bioaugmentation strategies that may eventually lead to better outcomes with better return-to-play rates and fewer revisions.

Paediatric and adolescent anterior cruciate ligament reconstruction surgery

Aims

Anterior cruciate ligament (ACL) surgery in children and the adolescent population has increased steadily over recent years. We used a national database to look at trends in ACL reconstruction and rates of serious complications, growth disturbance, and revision surgery, over 20 years.

Methods

All hospital episodes for patients undergoing ACL reconstruction, under the age of 20 years, between 1 April 1997 and 31 March 2017, were extracted by procedure code from the national Hospital Episode Statistics (HES). Population standardized rates of intervention were determined by age group and year of treatment. Subsequent rates of serious complications including reoperation for infection, growth disturbance (osteotomy, epiphysiodesis), revision reconstruction, and/or contralateral ACL reconstruction rates were determined.

Results

Over the 20 year period, 16,125 ACL reconstructions were included. The mean age of patients was 16.9 years (SD 2.0; 27.1% female, n = 4,374/16,125). The majority of procedures were observed in the 15 to 19 years age group. The rate of ACL reconstruction increased 29-fold from 1997 to 1998, to 2016 to 2017. Within 90 days of ACL reconstruction, the rate of reoperation for infection was 0.31% (95% confidence interval (CI) 0.23 to 0.41, n = 50/16,125) and the rate of pulmonary embolism was 0.037% (95%.CI 0.014 to 0.081, n = 6/16,125). Of those with minimum five-year follow-up following ACL reconstruction (n = 7,585), 1.00% of patients subsequently underwent an osteotomy (95% CI 0.79 to 1.25, n = 76/7,585), 0.09% an epiphysiodesis (95% CI 0.04 to 0.19, n = 7/7,585), 7.46% revision ACL reconstruction (95% CI 6.88 to 8.08, n = 566/7,585), and 6.37% contralateral ACL reconstruction (95% CI 5.83 to 6.94, n = 483/7,585).

Conclusion

Rates of paediatric and adolescent ACL reconstruction have increased 29-fold over the last 20 years. Despite the increasing rate in the younger population, the risk of serious complications, including further surgery for growth disturbance is very low. The results of our study provide a point of reference for shared decision making in the management of ACL injury in the paediatric and adolescent population. Cite this article: Bone Joint J 2020;102-B(2):239–245.

The single-suture technique for anterior cruciate ligament graft preparation provides similar stability as a three-suture technique: a biomechanical in vitro study in a porcine model

PURPOSE

Numerous techniques have been described for the tibial-sided graft preparation in anterior cruciate ligament (ACL) reconstruction. The use of less suture material for graft preparation is thought to improve ingrowth and to reduce the risk for infection. At the same time, the suture construct should be strong enough to resist the surgeon's pull during tensioning of the transplant.

METHODS

In total, 39 fresh-frozen procine deep flexor tendons were used and prepared as four-strand grafts. In the three-suture group (n = 19), graft preparation was performed using three tibial-sided sutures, with each tendon end sutured separately. In the one-suture group (n = 20), a modified graft preparation using only one tibial-sided suture was applied. Each sample underwent load-to-failure testing (N_max) after cyclic pre-loading. To estimate intraoperative tension forces acting on the tibial-sided suture constructs, the maximal tension force of 26 volunteers on such a construct was measured using a load cell.

RESULTS

The biomechanical testing of the two different suture constructs showed a significantly higher load-to-failure for the three-suture group (711 N ± 91 N) compared to the one-suture group (347 N ± 24 N) (p = 0.0001). In both groups, the mode of failure was a tear of the suture in all samples. A failure of the suture-tendon interface was not observed in any case. The median maximal tension force on the construct applied by the 26 volunteers was 134 N (range 73-182 N).

CONCLUSION

The presented single-suture tendon graft preparation resisted to smaller failure loads than the conventional three-suture technique. However, no failures in the suture-tendon interface were seen and the failure loads observed were far beyond the tension forces that can be expected intraoperatively. Hence, the single-suture graft preparation technique may be a valuable alternative to the conventional technique.

Anterior Cruciate Ligament Reconstruction With Suture Tape Augmentation: A Surgical Technique

The anterior cruciate ligament (ACL) is the most common ligamentous knee injury and often is encountered in those participating in multidirectional sports. ACL reconstruction is the most commonly performed knee ligament reconstruction and employs a variety of surgical techniques but still is challenged by residual laxity and graft rupture. To help address and prevent future ACL failures, new repair and reconstruction techniques have been employed that incorporate suture augmentation (InternalBrace; Arthrex, Naples, FL), which protects the graft during healing and ligamentization. Our goal of this article is to provide a surgical technique of suture augmentation with ACL reconstruction.

[Combined posterior and anterior cruciate ligament reconstruction : Arthroscopic treatment with the GraftLink® system]

OBJECTIVE

Simultaneous arthroscopic reconstruction of the anterior and/or posterior cruciate ligament (ACL/PCL) using the GraftLink® system (Arthrex) to obtain stable treatment and good functional results. The transplant is protected by the safety belt like biomechanical GraftLink® principle, which is used to secure the intraoperatively obtained stability in the long term.

INDICATIONS

ACL, PCL, or combined cruciate ligament rupture, especially multiligament injuries. Revision ACL and PCL reconstruction.

CONTRAINDICATIONS

Preoperative fixed posterior tibial subluxation. Reduced range of motion (ROM) with an extension lag (extension/flexion 0‑0-120° preoperatively required). Complex regional pain syndrome. High-grade atrophy of the quadriceps femoris muscle and osseous deformities.

SURGICAL TECHNIQUE

Supine position with mobile leg and possible flexion of at least 120° allowing antegrade femoral bone tunnel replacement. Retrograde tunnel placement (e. g. using a retrocutter) is recommended in case of less than 120° knee flexion. Thigh tourniquet. Staging arthroscopy. Cruciate ligament reconstruction is realized by anatomic tunnel placement for the ACL/PCL using the GraftLink®. Recommended sequence of reconstruction: 1. tibial PCL tunnel, 2. femoral ACL tunnel, 3. femoral PCL tunnel, 4. tibial ACL tunnel. Hybrid fixation is recommended. Portals: High anteromedial, high anterolateral, posteromedial, posterolateral, small subvastus incision.

POSTOPERATIVE MANAGEMENT

Combined cruciate ligament replacement: Gradual load and ROM increase in the PCL track. After postoperative week 5, increasing load up to full weight bearing, with extension/flexion 0‑0-90° after week 7. Down training of the PCL track after week 13. Contact and competitive sports after 1 year.

RESULTS

The GraftLink® system allows restoration of knee joint stability with good functional results. The procedure is especially suitable for complex situations like after knee dislocation with ACL and PCL reconstruction in 1 or 2 steps.