Vascular physiology and long-term healing of partial ligament tears

Comparable outcome for autografts and allografts in primary medial patellofemoral ligament reconstruction for patellofemoral instability: systematic review and meta-analysis

PURPOSE

This study updates the current evidence on the role of allografts versus autografts for medial patellofemoral ligament (MPFL) reconstruction in patients with patellofemoral instability.

METHODS

The study was performed according to the PRISMA guidelines. In March 2021, a literature search in the main online databases was performed. Studies reporting quantitative data concerning primary MPFL reconstruction using an allograft were considered for inclusion. The Coleman Methodology Score was used to assess the methodological quality of the selected articles.

RESULTS

Data from 12 studies (474 procedures) were retrieved. The mean follow-up was 42.2 (15-78.5) months. The mean age was 21.1 ± 6.2 years. 64.9% (285 of 439) of patients were female. At the last follow-up, the Tegner (p < 0.0001), Kujala (p = 0.002) and the Lysholm (p < 0.0001) scores were minimally greater in the autografts. The similarity was found in the rate of persistent instability sensation and revision. The allograft group evidenced a lower rate of re-dislocations (p = 0.003).

CONCLUSION

Allografts may represent a feasible alternative to traditional autograft for MPFL reconstruction in selected patients with patellofemoral instability. Allograft tendons yielded similar PROMs, rates of persistent instability, and revision. Allograft reconstructions tended to have modestly lower re-dislocation rates.

LEVEL OF EVIDENCE

IV.

Hybrid Remnant-Sparing Anterior Cruciate Ligament Repair-Reconstruction

In anterior cruciate ligament (ACL) reconstruction, the remnant ACL is often debrided in an effort to improve visualization of patient anatomy and reduce surgical difficulty. However, retention of the tibial remnant of a torn ACL theoretically portends several advantages. These include preservation of knee proprioception and mechanoreceptors, an enhanced biological environment for healing, and accelerated revascularization and ligamentization of the graft. Despite these advantages, it is not a widely adopted practice and the optimal technique is still subject to debate. The purpose of this technical note is to describe our preferred technique for performing hybrid ACL reconstruction with remnant incorporation.

Is it worth to perform initial non-operative treatment for patients with acute ACL injury?: a prospective cohort prognostic study

Purpose

To evaluate the result of implementing an initial non-operative treatment program for an acute ACL injury and to find if the timing of initiating the non-operative treatment is significant.

Methods

This study included a prospective cohort of 85 consecutive patients with acute ACL injury who were treated according to the above strategy for the initial 3 months with 1-year follow-up. Clinical evaluations were made by Lysholm score, Tegner activity score, Lachman test (LT), pivot-shit test (PST), and the side to side difference (SSD) by KT-2000 arthrometer. The results were analyzed according to the timing of initiating the non-operative treatment.

Results

Initially, 84% of the patients showed LT and PST ≤ grade 1, and 16% with ≥grade 2. At 1-year follow-up, 77 patients (91%) with LT and PST ≤ grade 1 did not receive reconstruction as copers and 8 patients with LT or PST ≥ grade 2 required reconstruction (six patients received the operation and two refused). The patients with LT and PST ≤ grade 1 showed average Lysholm score 91.2, average SSD 2.5 mm, and mean Tegner score decreased from 6.9 (pre-injury) to 6.2. Patients who started the non-operative treatment within 2 weeks after injury revealed superior rates of grade 0 or 1 instability than those who commenced the treatment later than 2 weeks after injury (P = 0.043).

Conclusions

Implementing a non-operative treatment with brace in acute phase of ACL injury appears to be an effective and viable option to achieve a reasonable clinical outcome. We recommend earlier initiation of the non-operative treatment to obtain a better result in patients with acute ACL injury.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43019-021-00094-3.

Long-term outcome and progression of osteoarthritis in uncomplicated cases of cranial cruciate ligament rupture treated by tibial plateau leveling osteotomy in dogs

The object of this study is to evaluate the long-term outcome of hind limb weight-bearing function and progression of stifle osteoarthritis (OA) after tibial plateau leveling osteotomy (TPLO). Groups were classified by the degree of cranial cruciate ligament (CrCL) damage and presence or absence of medial meniscus damage as macroscopically evaluated during surgery. Weight-bearing function was assessed via the peak vertical force (PVF), and OA progression was assessed via the radiographic OA score (OAS) preoperatively and 1, 3, 6, 12, 18, 24, and 36 months postoperatively. In all stifles, PVF was significantly higher within 6 months postoperatively than preoperatively, and this high ratio was maintained for 36 months. The OAS was significantly higher 24 months postoperatively than preoperatively in stifles with a partial CrCL tear, and significantly increased at each timepoint after 3 months postoperatively in stifles with complete CrCL rupture. The OAS remained consistently lower in stifles with a partial CrCL tear and no treatment of the medial meniscus than in stifles with complete rupture. Thus, after TPLO, the weight-bearing function improved in the early postoperative period and was maintained for as long as 36 months. Although OA progressed over time after TPLO, the progression was more gradual in stifles with partial tears than in those with complete rupture. Canine patients would benefit from earlier surgical intervention through development of technology that enables early detection of ligament degeneration.

Analysis of partial bundle anterior cruciate ligament tears- diagnosis and management with ACL augmentation

OBJECTIVES

Partial ACL tears are increasingly recognized in young active patients. They can evolve into complete tears. Controversy exists regarding the need to spare intact ACL bundle as it has its advantages considering biomechanical strength, blood supply and proprioception. The current study determined the challenges in partial ACL tear management and assessed the functional outcomes.

METHODS

Twenty consecutive patients with partial ACL tears were studied. Inclusion criteria were: age 16-45yrs and patients operated for partial ACL tear. Exclusion criteria were: combined ACL-PCL injuries, associated collateral injuries, complete ACL tear, chondral defect or bony malalignment and patients with radiographic signs of arthritis. 'Partial' tear was defined as continuous fibers from native tibial ACL footprint to native femoral ACL footprint in arthroscopy. Clinical and radiological assessment was done to evaluate anteromedial(AM) or posterolateral(PL) bundle tears. We used the term "ACL-augmentation" without disturbing the intact bundle or preserving the intact fibers as much as possible. Functional scoring was done using Lysholm score. Standard post-operative protocols were followed. Statistical analysis was done using SPSS software.

RESULTS

Mean age of patients was 31.2 years. Physically active age group (<30yrs) included 62.5% patients. Males were 87.5%. Pain and instability were the presenting complaints in 75% and 70% respectively. Average duration of presentation since injury was 4.2 months. Sports activities were the most common mode of injury (45%) followed by road traffic accidents (37.5%). Anterior drawer test was positive in 40%, pivot shift in 35% and Lachman test was positive in 65%. On arthroscopy, 65% had AM bundle tears and 35% had PL bundle tears. The intact bundle was found lax in 13% cases. Associated meniscal tear was present in 28% patients. Stiff knee was the most common post-operative complaint. Preoperative Lysholm knee score of 74.5 improved to 87.7 at 12months (p < 0.001). Around 97.5% of the patients reported outcomes as good and fair.

CONCLUSION

The treatment strategy needs to be individualized. The ACL augmentation needs more systematic and accurate placement of portals while sparing the intact ACL fibers. For AM bundle, tibial tunnel entry point is about 1-2 cm medial to tibial tuberosity. For PL bundle, it is about 3-4 cm medial to tibial tuberosity to protect the AM bundle. Long term studies with greater number of subjects are required.

Cruciate ligament healing and injury prevention in the age of regenerative medicine and technostress: homeostasis revisited

PURPOSE

This clinical concepts paper discusses the essential elements of cruciate ligament recuperation, micro-trauma repair, and remodeling.

METHODS

Cruciate ligament mechanobiology and tissue heterogeneity, anatomy and vascularity, and synovial membrane and fluid functions are discussed in relationship to deficiency-induced inflammatory responses, nervous and immune system function, recuperation, repair and remodeling, and modern threats to homeostasis.

RESULTS

Cruciate ligament surgical procedures do not appreciate the vital linked functions of the central, peripheral, and autonomic nervous systems and immune system function on knee ligament injury recuperation, micro-trauma repair, and remodeling. Enhanced knowledge of these systems could provide innovative ways to decrease primary non-contact knee injury rates and improve outcomes following reconstruction or primary repair.

CONCLUSIONS

Restoration of knee joint homeostasis is essential to cruciate ligament recuperation, micro-trauma repair, and remodeling. The nervous and immune systems are intricately involved in this process. Varying combinations of high-intensity training, under-recovery, technostress, and environmental pollutants (including noise) regularly expose many athletically active individuals to factors that abrogate the environment needed for cruciate ligament recuperation, micro-trauma repair, and remodeling. Current sports training practice, lifestyle psychobehaviors, and environmental factors combine to increase both primary non-contact knee injury risk and the nervous and immune system dysregulation that lead to poor sleep, increased anxiety, and poorly regulated hormone and cytokine levels. These factors may create a worst-case scenario leading to poor ligament recuperation, micro-trauma repair, and remodeling. Early recognition and modification of these factors may decrease knee ligament injury rates and improve cruciate ligament repair or reconstruction outcomes.

LEVEL OF EVIDENCE

V.

Anterior cruciate ligament remnant cells have different potentials for cell differentiation based on their location

Histological and cytological observations of the human anterior cruciate ligament (ACL) had been described, but the differentiation potency based on their location is still unknown. To determine and compare proliferation and differentiation potential of cells derived from distal and middle thirds of the ACL remnant, ACL remnant was initially marked at the distal third (within 10  mm from the tibial insertion) and middle third (between 10-20  mm from the tibial insertion) and then dissected. Both the middle and distal third regions of ACL remnant were analyzed using CD34+ cell counting. Cell proliferation rate did not differ in both middle and distal third regions of ACL remnant, but they showed different characteristics in cell differentiation depending on their location. The distal third region of the ACL remnant had a tendency for chondrogenic differentiation with higher expression of CD34+ cells. On the other hand, the middle third region of ACL remnant had a strong tendency for osteogenic and ligamentous differentiation. Characteristics of the ACL remnant tissues should be considered when performing remnant-preserving or harvesting ACL remnants for tissue engineering.

Selective bundle reconstruction in partial ACL tears leads to excellent long-term functional outcomes and a low percentage of failures

BACKGROUND

The optimal treatment of partial anterior cruciate ligament (ACL) tears continues to be debatable. Short-term results of selective bundle reconstruction have already been widely shown. The purpose of this study was to assess functional outcomes, subjective satisfaction and the failure rate of selective bundle reconstructions for partial ACL tears over a five to nine year follow-up period.

METHODS

Patients who underwent ACL selective bundle reconstruction between October 2008 and October 2012 were studied. Functional assessment was performed with the objective International Knee Documentation Committee (IKDC) ligament evaluation form, the Lysholm knee scale and the Tegner activity level scale. Cumulative failure and level of satisfaction have also been investigated.

RESULTS

Seventy-six patients were included. The average follow-up period was 85 months (range 65-110). Thirty-four had AMB tear and 42 had PLB tears. An overall statistically significant improvement (p < 0.001) was obtained in terms of the subjective IKDC and the Lysholm questionnaire between preoperative and last follow-up. The same or no more than one level lower Tegner score was restored in 97.3% of the cases. Cumulative failure was observed in two patients (2.6%). Dissatisfied patient percentage was 15% (4/76).

CONCLUSIONS

Selective bundle reconstruction in partial ACL tears leads to excellent long-term functional outcomes, a low percentage of failures and a high degree of subjective satisfaction in patients.

LEVEL OF EVIDENCE

Therapeutic case series; level 4.

Knitted Silk-Collagen Scaffold Incorporated with Ligament Stem/Progenitor Cells Sheet for Anterior Cruciate Ligament Reconstruction and Osteoarthritis Prevention

Current surgical management of anterior cruciate ligament (ACL) rupture still remains an intractable challenge in ACL regeneration due to the weak self-healing capability of ACL. Inadequate cell numbers and vascularization within the articular cavity contribute mainly to the poor prognosis. This time, we fabricated a new tissue engineering scaffold by adding ligament stem/progenitor cell (LSPC) sheets to our previous knitted silk-collagen sponge scaffold, which overcame these limitations by providing sufficient numbers of seed cells and a natural extracellular matrix to facilitate regeneration. LSPCs display excellent proliferation and multilineage differentiation capacity. Upon ectopic implantation, the knitted silk-collagen sponge scaffold incorporated with an LSPC sheet exhibited less immune cells but more fibroblast-like cells, deposited ECM and neovascularization, and better tissue ingrowth. In a rabbit model, we excised the ACL and performed a reconstructive surgery with our scaffold. Increased expression of ligament-specific genes and better collagen fibril formation could be observed after orthotopic transplantation. After 6 months, the LSPC sheet group showed better results on ligament regeneration and ligament-bone healing. Furthermore, no obvious cartilage and meniscus degeneration were observed at 6 months postoperation. In conclusion, these results indicated that the new tissue engineering scaffold can promote ACL regeneration and slow down the progression of osteoarthritis, thus suggesting its high clinical potential as an ideal graft in ACL reconstruction.

Vascular Pathology and Osteoarthritis: A Systematic Review

OBJECTIVE

Vascular pathology (changes in blood vessels) and osteoarthritis (OA) are both common chronic conditions associated with aging and obesity, but whether vascular pathology is a risk factor for OA is unclear. The aim of this study was to systematically review the evidence for an association between vascular pathology and risk of joint-specific OA.

METHODS

Scopus, Ovid Medline, and EMBASE were searched from inception to February 2019. MeSH terms and keywords were used to identify studies examining the association between vascular pathology and OA. Two reviewers independently extracted the data and assessed the methodological quality. Qualitative evidence synthesis was performed.

RESULTS

Fifteen studies with high (n = 3), fair (n = 3), or low (n = 9) quality were included. Features of vascular pathology included atherosclerosis, vascular stiffness, and endothelial dysfunction in different vascular beds. There was evidence for an association between vascular pathology and risk of hand OA in women but not men, and between vascular pathology and risk of knee OA in both men and women. Only 2 studies examined hip OA showing no association between vascular pathology and risk of hip OA.

CONCLUSION

There is evidence suggesting an association between vascular pathology and risk of hand and knee OA, with a potential causal relationship for knee OA. Based on the limited evidence, it is hard to conclude an association for hip OA. Further stronger evidence is needed to determine whether there is a causal relationship.

Ultrastructural and histological changes in tibial remnant of ruptured anterior cruciate ligament stumps: a transmission electron microscopy and immunochemistry-based observational study

OBJECTIVES

Anterior cruciate ligament (ACL) rupture is a common injury and has a non-union rate of 40-100%. Important cellular events, such as fibroblast proliferation, angiogenesis and change in collagen fibril thickness in the ACL remnant, as described in other dense connective tissue, might have an implication in graft recovery following ACL reconstruction. Thus we conducted a study with an aim to characterize the ultrastructural and histological features of ruptured ACL tibial stump and correlate the same with the duration of injury.

MATERIALS AND METHODS

This was a prospective observational study in which 60 ruptured human ACLs were evaluated for collagen fibril thickness, blood vessel density (per mm²) and fibroblast density (per mm²) with the help of transmission electron microscopy, immunohistochemistry via CD34 antibody staining and light microscopy (H&E staining). The findings were correlated with duration of injury.

RESULTS

Fifty-four male and six female patients with a mean duration of the injury of 23.01 weeks (SD = 26.09; range 2-108 weeks) were included for the study and were divided on the basis of duration of injury as follows: Group I (≤ 6 weeks; N = 16), Group II (7-12 weeks; N = 18), Group III (13-20 weeks; N = 7), Group IV (21-50 weeks; N = 12), Group V (> 50 weeks; N = 7). A significant correlation was seen with blood vessel density (r = 0.303, p = 0.01) and fibroblast density (r = - 0.503, p = 0.001). Thickness of collagen fibril did not correlate with the duration of injury (r = 0.15, p = 0.23). The thickness of the collagen reached its peak after 50 weeks following injury, whereas highest density of blood vessel and fibroblast was seen at 12-20 weeks. Matched pair analysis revealed a significant decrease in collagen fibril thickness and an increase in fibroblast density at 7-12 weeks.

CONCLUSION

Following injury to ACL, the ruptured tibial stump undergoes a series of changes at the cellular level vis-à-vis changes in collagen fibril thickness, vascular density and fibroblast density that possibly suggest an intrinsic healing response. This further may have implications on the functional outcome following ACL reconstruction with remnant preservation.

LEVEL OF EVIDENCE

III.

Does Remnant Preservation Influence Tibial Tunnel Enlargement or Graft-to-Bone Integration After Double-Bundle Anterior Cruciate Ligament Reconstruction Using Hamstring Autografts and Suspensory Fixation? A Computed Tomography and Magnetic Resonance Imaging Evaluation

Background:

Remnant-preserving anterior cruciate ligament (ACL) reconstruction was introduced to improve clinical outcomes and biological healing. However, the influences of remnant preservation on tibial tunnel position and enlargement are still uncertain.

Purpose:

To evaluate whether remnant-preserving ACL reconstruction influences tibial tunnel position or enlargement and to examine the relationship between tunnel enlargement and graft-to-bone integration in the tibial tunnel.

Study Design:

Cohort study; Level of evidence, 2.

Methods:

A total of 91 knees with double-bundle ACL reconstructions were enrolled in this study. ACL reconstruction was performed without a remnant (<25% of the intra-articular portion of the graft) in 44 knees (nonremnant [NR] group) and with remnant preservation in the remaining 47 knees (remnant-preserving [RP] group). Tibial tunnel position and enlargement were assessed using computed tomography (CT). Comparisons between groups were performed. Furthermore, graft-to-bone integration in the tibial tunnel was evaluated using magnetic resonance imaging, and the relationship between tunnel enlargement and graft-to-bone integration at 1 year after ACL reconstruction was assessed.

Results:

A total of 48 knees (25 in NR group, 23 in RP group) were included; 19 and 24 knees in the NR and RP groups were excluded, respectively, because of graft reruptures and a lack of CT scans. There were no significant between-group differences in tibial tunnel position (P > .05). The degree of posterolateral tunnel enlargement in the axial plane was significantly higher in the RP group than that in the NR group (P = .007) 1 year after ACL reconstruction. The degree of anteromedial tunnel enlargement on axial CT was significantly smaller in knees with graft-to-bone integration than in those without integration (P = .002) 1 year after ACL reconstruction.

Conclusion:

ACL reconstruction with remnant preservation did not influence tibial tunnel position and did not decrease the degree or incidence of tibial tunnel enlargement. At 1 year postoperatively, tunnel enlargement did not affect graft-to-bone integration in the posterolateral tunnel, but graft-to-bone integration was delayed in the anteromedial tunnel.

Predictive Factors of Hamstring Tendon Regeneration and Functional Recovery After Harvesting: A Prospective Follow-up Study

BACKGROUND

Semitendinosus and gracilis tendons may regenerate after harvesting for ligament reconstruction procedures. However, predictive factors of tendon regeneration and the extent of functional recovery remain unclear.

PURPOSE

To identify predictive factors for hamstring tendon regeneration and to examine the morbidity of nonregenerated hamstring tendons.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Of the 154 patients who were included in a prospective follow-up study, 79 underwent reconstruction of the anterior cruciate ligament entailing the hamstring tendons and met the following inclusion criteria: (1) anterior cruciate ligament rupture diagnosed by physical examination and magnetic resonance imaging (MRI), (2) MRI within 6 months after trauma, (3) age between 18 and 45 years, and (4) 2-year follow-up MRI data available. Hamstring tendon regeneration was assessed as complete if a tendon-like structure could be visualized at the level of the joint line or more cranially. Patient characteristics-such as age, sex, body mass index, alcohol/nicotine use, activity level (Tegner scores), and functional instability (1-legged hop test)-were evaluated preoperatively and at 2 years to determine predictive factors for tendon regeneration or examine functional recovery of hamstring tendon regeneration.

RESULTS

At 2 years' follow-up, 67.1% of the patients showed regeneration of semitendinosus tendons, 81.0% of gracilis tendons, and 59.5% of both tendons. The likelihood of semitendinosus tendon regeneration significantly decreased with aging (odds ratio [OR], 0.92 change per year of age; 95% CI, 0.84-0.99; P = .03) and smoking (OR, 0.20; 95% CI, 0.05-0.77; P = .02). No predictive factor was found for gracilis tendon regeneration. Regeneration of the semitendinosus and gracilis tendons was negatively related with smoking (OR, 0.22; 95% CI, 0.06-0.79; P = .02). Patients without regeneration showed similar postoperative visual analog scale scores during physical activity, similar Tegner scores, and a significant decrease of the upper leg circumference, as compared with their preoperative results. Regardless of the regeneration status, 1-legged hop test results significantly increased at 2-year follow-up.

CONCLUSION

Hamstring tendon regeneration occurs less frequently in older patients and in smokers. However, absence of regenerated tendons does not seem to cause a loss of function.

Complex knee injuries treated in acute phase: Long-term results using Ligament Augmentation and Reconstruction System artificial ligament

AIM

To present the long-term results of complex knee injuries, treated early using the Ligament Augmentation and Reconstruction System (LARS) artificial ligament to reconstruct posterior cruciate ligament (PCL).

METHODS

From September 1997 to June 2010, thirty-eight complex knee injuries were treated, where early arthroscopic PCL reconstructions were undergone, using the LARS (Surgical Implants and Devices, Arc-sur-Tille, France) artificial ligament. Exclusion criteria were: Late (> 4 wk) reconstruction, open technique, isolated PCL reconstruction, knee degenerative disease, combined fracture or vascular injury and use of allograft or autograft for PCL reconstruction. Clinical and functional outcomes were assessed with IKDC Subjective Knee Form, KOS-ADLS questionnaire, Lysholm scale and SF-12 Health Survey. Posterior displacement (PD) was measured with the Telos Stress Device.

RESULTS

Seven patients were excluded; two because of co-existing knee osteoarthritis and the remaining five because of failure to attend the final follow-up. The sample consisted of 31 patients with mean age at the time of reconstruction 33.2 ± 12.5 years (range 17-61). The postoperative follow-up was on average 9.27 ± 4.27 years (range 5-18). The mean average IKDC and KOS scores were 79.32 ± 17.1 and 88.1 ± 12.47% respectively. Average PD was 3.61 ± 2.15 mm compared to 0.91 ± 1.17 mm in the uninjured knees (one with grade 1 + and two with grade 2 +). Dial test was found positive in one patient, whereas the quadriceps active drawer test was positive in three patients. None was tested positive on the reverse-pivot shift test. The range of motion (ROM) was normal in thirty knees, in comparison with the contralateral one. There was no extension deficit. Osteoarthritic changes were found in three knees (9.6%).

CONCLUSION

Early treatment of complex knee injuries, using LARS artificial ligament for PCL reconstruction sufficiently reduces posterior tibia displacement and provides satisfactory long-term functional outcomes.

Investigation of angiogenesis genes with anterior cruciate ligament rupture risk in a South African population

The angiogenesis-signalling pathway is a physiological response after mechanical loading to promote matrix remodelling and thereby maintain tissue homeostasis. Studies have shown increased expression of angiogenic molecules in response to loading and in ruptured ligaments. Recently, polymorphisms within the vascular endothelial growth factor A (VEGFA) and kinase insert-domain receptor (KDR) genes were associated with risk of anterior cruciate ligament (ACL) ruptures and Achilles tendinopathy in Caucasian study groups. A case-control genetic association study was conducted on 100 controls and 98 participants with surgically-diagnosed ACL ruptures; of which 51 participants reported non-contact mechanism of injury (NON). All participants were genotyped for five functional polymorphisms: VEGFA (rs699947, rs1570360, rs2010963) and KDR (rs2071559, rs1870377). Haplotypes were inferred. In the male participants, the KDR rs2071559 AG genotype was significantly over-represented (P = 0.048, OR: 1.90, 95% CI: 1.00-3.59) in the controls. Furthermore, the GG genotype was significantly under-represented in the male controls compared to the male ACL group (P = 0.018, OR: 2.77, 95% CI: 1.17-6.55) and the male NON subgroup (P = 0.013, OR: 3.26, 95% CI: 1.24-8.58). Haplotype analysis implicated the KDR gene in all participants and in male participants separately. Collectively, these results implicate the angiogenesis-signalling pathway as a potentially key biological pathway contributing to ACL injury susceptibility.

Is Remnant Preservation Truly Beneficial to Anterior Cruciate Ligament Reconstruction Healing? Clinical and Magnetic Resonance Imaging Evaluations of Remnant-Preserved Reconstruction

BACKGROUND

Remnant-preserved anterior cruciate ligament (ACL) reconstruction was introduced to improve clinical outcomes and biological healing. However, the effects of remnant preservation and the influence of the delay from injury until reconstruction on the outcomes of this technique are still uncertain. Purpose/Hypothesis: The purposes of this study were to evaluate whether remnant preservation improved the clinical outcomes and graft incorporation of ACL reconstruction and to examine the influence of the delay between ACL injury and reconstruction on the usefulness of remnant preservation. We hypothesized that remnant preservation improves clinical results and accelerates graft incorporation and that its effect is dependent on the delay between ACL injury and reconstruction.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A total of 151 consecutive patients who underwent double-bundle ACL reconstruction using a semitendinosus graft were enrolled in this study: 74 knees underwent ACL reconstruction without a remnant (or the remnant was <25% of the intra-articular portion of the graft; NR group), while 77 knees underwent ACL reconstruction with remnant preservation (RP group). These were divided into 4 subgroups based on the time from injury to surgery: phase 1 was <3 weeks (n = 24), phase 2 was 3 to less than 8 weeks (n = 70), phase 3 was 8 to 20 weeks (n = 32), and phase 4 was >20 weeks (n = 25). Clinical measurements, including KT-1000 arthrometer side-to-side anterior tibial translation measurements, were assessed at 3, 6, 12, and 24 months after reconstruction. Magnetic resonance imaging evaluations of graft maturation and graft-tunnel integration of the anteromedial and posterolateral bundles were assessed at 3, 6, and 12 months after reconstruction.

RESULTS

There was no difference in side-to-side anterior tibial translation between the NR and RP groups. There was also no difference in graft maturation between the 2 groups. Furthermore, the time from ACL injury until reconstruction did not affect graft maturation, except in the case of very long delays before reconstruction (phase 4). Graft-tunnel integration was significantly increased in both groups in a time-dependent manner. However, there was no difference between the NR and RP groups.

CONCLUSION

Remnant preservation did not improve knee stability at 2 years after ACL reconstruction. Furthermore, remnant preservation did not accelerate graft incorporation, especially during the acute and subacute injury phases.

Mechanical Loading Improves Tendon-Bone Healing in a Rabbit Anterior Cruciate Ligament Reconstruction Model by Promoting Proliferation and Matrix Formation of Mesenchymal Stem Cells and Tendon Cells

Background/Aims: This study investigated the effect of mechanical stress on tendon-bone healing in a rabbit anterior cruciate ligament (ACL) reconstruction model as well as cell proliferation and matrix formation in co-culture of bone-marrow mesenchymal stem cells (BMSCs) and tendon cells (TCs). Methods: The effect of continuous passive motion (CPM) therapy on tendon-bone healing in a rabbit ACL reconstruction model was evaluated by histological analysis, biomechanical testing and gene expressions at the tendon-bone interface. Furthermore, the effect of mechanical stretch on cell proliferation and matrix synthesis in BMSC/TC co-culture was also examined. Results: Postoperative CPM therapy significantly enhanced tendon-bone healing, as evidenced by increased amount of fibrocartilage, elevated ultimate load to failure levels, and up-regulated gene expressions of Collagen I, alkaline phosphatase, osteopontin, Tenascin C and tenomodulin at the tendon-bone junction. In addition, BMSC/TC co-culture treated with mechanical stretch showed a higher rate of cell proliferation and enhanced expressions of Collagen I, Collagen III, alkaline phosphatase, osteopontin, Tenascin C and tenomodulin than that of controls. Conclusion: These results demonstrated that proliferation and differentiation of local precursor cells could be enhanced by mechanical stimulation, which results in enhanced regenerative potential of BMSCs and TCs in tendon-bone healing.

Short term results of anterior cruciate ligament augmentation in professional and amateur athletes

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction is a widely accepted procedure; however, controversies exist about ACL augmentation. The purpose of this study was to assess the clinical outcomes of ACL augmentation in professional and amateur athletes with isolated single bundle ACL tears.

MATERIALS AND METHODS

A consecutive series of professional and amateur athletes with partial ACL tears who underwent selective bundle reconstruction were analyzed. Stability was assessed with the Lachman test, anterior-drawer test, pivot-shift test and KT-1000 arthrometer. Functional assessment was performed using the subjective Lysholm questionnaire.

RESULTS

Fifty-six patients were enrolled. The mean follow-up period was 19.3 months. All patients had posterolateral bundle (PLB) tears, and no anteromedial bundle (AMB) tears were found. The Lysholm score improved significantly from 78 (SD = 2.69) preoperatively to 96 (SD = 3.41) postoperatively (P value <0.0001). The pivot-shift test, Lachman test and anterior-drawer test results were negative in all cases postoperatively. Anterior tibial translation from neutral was 4.9 mm (SD = 2.7) preoperatively, and decreased significantly to 2.1 (SD = 0.6) postoperatively, measured with a KT-1000 arthrometer (P value <0.00001).

CONCLUSION

In this study, we showed that ACL augmentation had good results in symptomatic professional and amateur athletes, and although further studies are needed to investigate long-term results, we recommend this surgery for all symptomatic athletic patients, especially those who would like to maintain an active lifestyle. Level of evidence IV.

Effects of Remnant Tissue Preservation on the Tendon Graft in Anterior Cruciate Ligament Reconstruction: A Biomechanical and Histological Study

BACKGROUND

There is controversy regarding the efficacy of remnant tissue preservation on graft healing in anterior cruciate ligament (ACL) reconstruction.

HYPOTHESIS

The preserved remnant tissue will (1) adhere to the graft surface and undergo a remodeling process, (2) accelerate graft revascularization, (3) increase the number of graft mechanoreceptors by 4 weeks, and (4) improve anteroposterior knee laxity and structural properties of the graft by 12 weeks.

STUDY DESIGN

Controlled laboratory study.

METHODS

Forty-two sheep were randomly divided into 2 groups of 21 animals. In group I, the ACL was completely removed. In group II, the ACL was transected at the midsubstance but not debrided. ACL reconstruction was performed using a semitendinosus tendon autograft in both groups. Histological changes of the grafted tendon and the remnant tissue were evaluated at 4 and 12 weeks after surgery. Biomechanically, anterior translation and knee joint stiffness under an anterior drawer force and the structural properties of the femur-graft-tibia complex were evaluated.

RESULTS

The preserved remnant tissue was histologically distinct from the graft at 4 weeks, while the tissue partially adhered to the graft surface at 12 weeks. The ACL remnant tissue significantly accelerated revascularization in the grafted tendon at 4 weeks and significantly increased the number of mechanoreceptors at 4 and 12 weeks. In addition, remnant preservation significantly improved anterior translation (9.3 ± 2.1 mm and 5.4 ± 1.7 mm at 60° of knee flexion in groups I and II, respectively) and knee joint stiffness at 12 weeks. However, there were no significant differences in the structural properties between the 2 groups at 4 and 12 weeks after surgery.

CONCLUSION

Preservation of the ACL remnant tissue in ACL reconstruction enhanced cell proliferation, revascularization, and regeneration of proprioceptive organs in the reconstructed ACL and reduced anterior translation. However, remnant preservation did not improve the structural properties of the graft.

CLINICAL RELEVANCE

These results imply that preservation of the ACL remnant tissue may improve graft healing after ACL reconstruction.

Anterior Cruciate Ligament: Structure, Injuries and Regenerative Treatments

Anterior cruciate ligament (ACL) is one of the most vulnerable ligaments of the knee. ACL impairment results in episodic instability, chondral and meniscal injury and early osteoarthritis. The poor self-healing capacity of ACL makes surgical treatment inevitable. Current ACL reconstructions include a substitution of torn ACL via biological grafts such as autograft, allograft. This review provides an insight of ACL structure, orientation and properties followed by comparing the performance of various constructs that have been used for ACL replacement. New approaches, undertaken to induce ACL regeneration and fabricate biomimetic scaffolds, are also discussed.

CT assessment of femoral tunnel placement after partial ACL reconstruction

INTRODUCTION

When one of the anterior cruciate ligament (ACL) bundles is torn, it seems appropriate to preserve the remaining bundle to improve the vascularization and proprioception of the graft, and to reproduce the attachment sites of the torn bundle. After ACL reconstruction, the functional result is worse when the tunnels are positioned further away from the native ACL's isometric attachment points. The goal of this study was to use CT 3D reconstructions to analyse the position of the femoral tunnel following partial ACL reconstruction and to compare it to complete ACL reconstruction cases. We hypothesized that the femoral tunnel positioning was optimal during partial ACL reconstruction.

METHODS

In this prospective single-centre study, 16 patients who underwent isolated anteromedial bundle reconstruction were evaluated during the immediate postoperative period using 3D reconstruction of CT images. During this same period, 180 patients who underwent complete ACL reconstruction in the same surgery unit served as a control group.

RESULTS

In the partial ACL reconstruction group, 6 tunnels (37.5%) were in the optimal position and 10 tunnels (62.5%) were not. In the complete ACL reconstruction group, 124 femoral (68.9%) were in the optimal position and 56 (31.1%) were not (P<0.05).

DISCUSSION

Femoral tunnel positioning is not always optimal in patients who undergo partial ACL reconstruction. Three-dimensional CT reconstruction is a good tool to help surgeons detect and learn from their errors.

LEVEL OF EVIDENCE

III (case-control study).

Biomechanical and Biological Findings Between Acute Anterior Cruciate Ligament Reconstruction With and Without an Augmented Remnant Repair: A Comparative in Vivo Animal Study

PURPOSE

To investigate whether remnant-preserving anterior cruciate ligament reconstruction (ACLR) for acute complete anterior cruciate ligament (ACL) tears can improve the biomechanical strength, revascularization status, and proprioceptive recovery potential of the grafted tendons compared with conventional ACLR.

METHODS

An acute complete ACL femoral detachment model was created in 60 rabbits. The animals were randomly allocated into the remnant-repairing ACLR group (group 1, n = 30) or the conventional ACLR group (group 2, n = 30). The ACL remnants were either acutely repaired with a femoral tensioning technique in group 1 or completely debrided in group 2. For group 1, remnant structural integrity was evaluated macroscopically and divided into grade A (bridging femur and tibia) and grade B (not bridging femur and tibia). Then, the remnant-to-graft healing capacity was assessed histologically. For intergroup comparisons, the biomechanical strength of the grafted tendons was evaluated by tensile tests and the revascularization status (vascular endothelial growth factor) and proprioceptive recovery potential (neurofilament) of the grafted tendons were evaluated by immunofluorescent staining. All assessments were performed postoperatively at week 24.

RESULTS

In group 1, 60% of remnants (18 of 30) showed grade A and 40% (12 of 30) showed grade B structural integrity. An obvious remnant-to-graft interval could be detected through the whole length of the graft. Tensile tests showed that the ultimate failure loads of the grafted tendons were similar between the groups (P = .365). In addition, there were no significant differences in the number of vascular endothelial growth factor-positive vessels and neurofilament-positive mechanoreceptors at either the femoral (P = .887 and P = .578, respectively), midsubstance (P = .063 and P = .546, respectively), or tibial (P = .193 and P = .978, respectively) level within the grafted tendons between the groups.

CONCLUSIONS

The acute remnant-repairing ACLR in our rabbit femoral ACL detachment model showed no biomechanical and biological advantages compared with conventional ACLR. The acutely repaired ACL remnants presented a high proportion of poor structural integrity and low remnant-to-graft healing capacity.

CLINICAL RELEVANCE

During our clinical practice, conventional ACLR may still not be replaced by remnant-repairing ACLR for the treatment of acute complete ACL tears.

Central defect type partial ACL injury model on goat knees: the effect of infrapatellar fat pad excision

Background

The mid-substance central defect injury has been used to investigate the primary healing capacity of the anterior cruciate ligament (ACL) in a goat model. The sagittal plane stability on this model has not been confirmed, and possible effects of fat pad excision on healing have not been evaluated. We hypothesize that excising the fat pad tissue results in poorer ligament healing as assessed histologically and decreased tensile strength of the healing ligament. We further hypothesize that the creation of a central defect does not affect sagittal plane knee stability.

Methods

A mid-substance central defect was created with a 4-mm arthroscopic punch in the ACLs of right knees of all the subjects through a medial mini-arthrotomy. Goats were assigned to groups based on whether the fat pad was preserved (group 1, n = 5) or excised completely (group 2, n = 5). The left knees served as controls in each goat. Histopathology of the defect area along with measurement of type I collagen in one goat from each group were performed at 10th week postoperatively. The remaining knees were evaluated biomechanically at the 12th week, by measuring anterior tibial translation (ATT) of the knee joints at 90° of flexion and testing tensile properties (ultimate tensile load (UTL), ultimate elongation (UE), stiffness (S), failure mode (FM)) of the femur-ACL-tibia complex.

Results and discussion

Histopathology analysis revealed that the central defect area was fully filled macroscopically and microscopically. However, myxoid degeneration and fibrosis were observed in group 2 and increased collagen type I content was noted in group 2. There were no significant differences within and between groups in terms of ATT values (p = 0.715 and p = 0.149, respectively). There were no significance between or within groups in terms of ultimate tensile load and ultimate elongation; however, group 2 demonstrated greater stiffness than group 1 that was correlated with the fibrotic changes detected microscopically (p = 0.043).

Conclusions

The central defect type injury model was confirmed to be biomechanically stable in a goat model. Resection of the fat pad was noted to negatively affect defect healing and increase ligament stiffness in the central defect injury model.

Poly(vinyl alcohol) hydrogel coatings with tunable surface exposure of hydroxyapatite

Insufficient bone anchoring is a major limitation of artificial substitutes for connective osteoarticular tissues. The use of coatings containing osseoconductive ceramic particles is one of the actively explored strategies to improve osseointegration and strengthen the bone-implant interface for general tissue engineering. Our hypothesis is that hydroxyapatite (HA) particles can be coated robustly on specific assemblies of PVA hydrogel fibers for the potential anchoring of ligament replacements. A simple dip-coating method is described to produce composite coatings made of microscopic hydroxyapatite (HA) particles dispersed in a poly(vinyl alcohol) (PVA) matrix. The materials are compatible with the requirements for implant Good Manufacturing Practices. They are applied to coat bundles of PVA hydrogel fibers used for the development of ligament implants. By means of optical and electronic microscopy, we show that the coating thickness and surface state can be adjusted by varying the composition of the dipping solution. Quantitative analysis based on backscattered electron microscopy show that the exposure of HA at the coating surface can be tuned from 0 to over 55% by decreasing the weight ratio of PVA over HA from 0.4 to 0.1. Abrasion experiments simulating bone-implant contact illustrate how the coating cohesion and wear resistance increase by increasing the content of PVA relative to HA. Using pullout experiments, we find that these coatings adhere well to the fiber bundles and detach by propagation of a crack inside the coating. These results provide a guide to select coated implants for anchoring artificial ligaments.

Positive effects of an extracellular matrix hydrogel on rat anterior cruciate ligament fibroblast proliferation and collagen mRNA expression

Background/Objective

We have previously shown that an extracellular matrix (ECM) bioscaffold derived from porcine small intestine submucosa (SIS) enhanced the healing of a gap injury of the medial collateral ligament as well as the central third defect of the patellar tendon. With the addition of a hydrogel form of SIS, we found that a transected goat anterior cruciate ligament (ACL) could also be healed. The result begs the research question of whether SIS hydrogel has positive effects on ACL fibroblasts (ACLFs) and thus facilitates ACL healing.

Methods

In the study, ECM-SIS hydrogel was fabricated from the digestion of decellularised and sterilised sheets of SIS derived from αGal-deficient (GalSafe) pigs. As a comparison, a pure collagen hydrogel was also fabricated from commercial collagen type I solution. The morphometrics of hydrogels was assessed with scanning electron microscopy. The ECM-SIS and collagen hydrogels had similar fibre diameters (0.105 ± 0.010 μm vs. 0.114 ± 0.004 μm), fibre orientation (0.51 ± 0.02 vs. 0.52 ± 0.02), and pore size (0.092 ± 0.012 μm vs. 0.087 ± 0.008 μm). The preservation of bioactive properties of SIS hydrogel was assessed by detecting bioactive molecules sensitive to processing and enzyme digestion, such as growth factors fibroblast growth factor-2 (FGF-2) and transforming growth factor-beta 1 (TGF-β1), with enzyme-linked immunosorbent assay. ACLFs were isolated and expanded in culture from explants of rat ACLs (n = 3). The cells were then seeded on the hydrogels and cultured with 0%, 1%, and 10% foetal bovine serum (FBS) for 3 days and 7 days. Cell attachment was observed using a light microscope and scanning electron microscopy, whereas cell proliferation and matrix production (collagen types I and III) were examined with bromodeoxyuridine assays and reverse transcription-polymerase chain reaction, respectively.

Results

The results showed that FGF-2 and TGF-β1 in the SIS hydrogel were preserved by 50% (65.9 ± 26.1 ng/g dry SIS) and 90% (4.4 ± 0.6 ng/g dry SIS) relative to their contents in ECM-SIS sheets, respectively. At Day 3 of culture, ACLFs on the SIS hydrogel were found to proliferate 39%, 31%, and 22% more than those on the pure collagen hydrogel at 0%, 1%, and 10% FBS, respectively (p < 0.05). Collagen type I mRNA expression was increased by 150%, 207%, and 100%, respectively, compared to collagen hydrogel (p < 0.05), whereas collagen type III mRNA expression was increased by 123% and 132% at 0% and 1% FBS, respectively (all p < 0.05) but not at 10% FBS. By Day 7, collagen type I mRNA expression was still elevated by 137% and 100% compared to collagen hydrogel at 1% and 10% FBS, respectively (p < 0.05). Yet, collagen type III mRNA levels were not significantly different between the two groups at any FBS concentrations.

Conclusion

Our data showed that the ECM-SIS hydrogel not only supported the growth of ACLFs, but also promoted their proliferation and matrix production relative to a pure collagen hydrogel. As such, ECM-SIS hydrogel has potential therapeutic value to facilitate ACL healing at the early stage after injury.

Partial tears of anterior cruciate ligament: Results of single bundle augmentation

BACKGROUND

Partial tears of the anterior cruciate ligament (ACL) are common and usually present with symptomatic instability. The remnant fibers are usually removed and a traditional ACL reconstruction is done. But with increased understanding of ACL double bundle anatomy, the remnant tissue preservation along with a single bundle augmentation of the torn bundle is also suggested. The purpose of this study was to evaluate the results of selective anatomic augmentation of symptomatic partial ACL tears. Our hypothesis is that this selective augmentation of partial ACL tears could restore knee stability and function.

MATERIALS AND METHODS

Consecutive cases of 314 ACL reconstructions, 40 patients had intact ACL fibers in the location corresponding to the anteromedial (AM) or posterolateral (PL) bundle and were diagnosed as partial ACL tears perioperatively. All patients underwent selective augmentation of the torn bundle, while keeping the remaining fibers intact using autogenous hamstring graft. A total of 38 patients (28 males, 10 females) were available with a minimum of 3 years followup. 26 cases had AM bundle tears and 12 cases had PL bundle tears respectively. Patients were assessed with International Knee Documentation Committee (IKDC) 2000 Knee Evaluation Form, Lysholm score; instrumented knee testing was performed with the arthrometer (KT 2000). Statistical analysis was performed to compare the preoperative and postoperative objective evaluation.

RESULTS

At 3 years followup, 31.6% patients were graded A, 65.8% were graded B and 2.6% was graded C at IKDC objective evaluation. Manual laxity tests, Lysholm's score, mean side to side instrumental laxity and Tegner activity score improved significantly. 76% patients returned to preinjury level of sports activity after augmentation.

CONCLUSION

The results of anatomic single bundle augmentation in partial ACL tears are encouraging with excellent improvement in functional scores, side to side laxity and return to sports activity.

Hamstring tendon autograft versus LARS artificial ligament for arthroscopic posterior cruciate ligament reconstruction in a long-term follow-up

INTRODUCTION

Surgical reconstruction has been increasingly recommended for the surgical management of posterior cruciate ligament (PCL) ruptures. While the choice of tissue graft still remains controversial. Currently both hamstring tendon autograft (HTG) and ligament advanced reinforcement system (LARS) artificial ligament are widely used but there are seldom reports on the comparisons of their clinical results. Our study was aimed to assess the effectiveness of these two grafts.

MATERIALS AND METHODS

Thirty-five patients with unilateral PCL rupture were enrolled in this retrospectively study. Sixteen of them received arthroscopically assisted PCL reconstruction using hamstring tendon autografts (HTG group) and nineteen using LARS ligaments (LARS group). All cases were followed up for 46-57 months with a mean of 51 months. Follow-up examinations included radiographic assessment, Lysholm score, Tegner score, International Knee Documentation Committee (IKDC) rating scales and KT-1000 test.

RESULTS

All patients improved significantly at the final follow-up compared with the examinational results preoperatively and there were no significant differences between HTG group and LARS group with respect to the results of radiographic assessment, Lysholm score, Tegner score, IKDC rating scales and KT-1000 test.

CONCLUSIONS

Similar good clinical results were obtained after PCL reconstruction using hamstring tendon autografts and LARS ligaments. Both LARS ligament and hamstring tendon autograft are ideal grafts for PCL reconstruction.

Influence of TNF-α and biomechanical stress on matrix metalloproteinases and lysyl oxidases expressions in human knee synovial fibroblasts

PURPOSE

It was reported that not only ACL but also the synovium may be the major regulator of matrix metalloproteinases (MMPs) in synovial fluids after ACL injury. In order to further confirm whether synovium is capable of regulating the microenvironment in the process of ACL injury, the complicated microenvironment of joint cavity after ACL injury was mimicked and the combined effects of mechanical injury and inflammatory factor [tumour necrosis factor-α (TNF-α)] on expressions of lysyl oxidases (LOXs) and MMPs in synovial fibroblasts derived from normal human synovium were studied.

METHODS

Human normal knee joint synovial fibroblasts were stimulated for 1-6 h with mechanical stretch and inflammatory factor (TNF-α). Total RNA was harvested, reverse transcribed and assessed by real-time polymerase chain reaction for the expression of LOXs and MMP-1, 2, 3 messenger RNAs. MMP-2 activity was assayed from the collected culture media samples using zymography.

RESULTS

Compared to control group, our results showed that 6% physiological stretch increased MMP-2 and LOXs (except LOXL-3), decreased MMP-1 and MMP-3; injurious stretch (12%) decreased LOXs (except LOXL-2)and increased MMP-1, 2 and 3; the combination of injurious stretch and TNF-α decreased LOXs and increased MMP-1, 2 and 3 in synovial fibroblasts in a synergistical manner.

CONCLUSION

This study demonstrated that combination of mechanical injury and inflammatory factors up-regulated the expressions of MMPs and down-regulated the expressions of LOXs in synovial fibroblasts, eventually alter the balance of tissue healing. Thus, synovium may be involved in regulating the microenvironment of joint cavity. Based on the mechanism, early interventions to inhibit the production of MMPs or promote the production of LOXs in the synovial fibroblasts should be performed to facilitate the healing of tissue.

Clinical, Functional, and Morphological Evaluations of Posterior Cruciate Ligament Reconstruction With Remnant Preservation: Minimum 2-Year Follow-up

BACKGROUND

Numerous posterior cruciate ligament (PCL) reconstruction techniques have evolved and have revealed satisfactory outcomes; however, the optimal operative method for PCL reconstruction remains controversial.

HYPOTHESIS

Transtibial PCL reconstruction with a remnant preservation technique would result in successful clinical, radiological, functional, and morphological outcomes. In addition, it was hypothesized that the results of combined PCL and posterolateral corner (PLC) reconstruction would be comparable with those of isolated PCL reconstruction.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 168 patients who underwent arthroscopic PCL reconstruction with or without reconstruction of the PLC between March 2006 and June 2011 were retrospectively reviewed. Ninety-two patients who met the inclusion criteria were enrolled, and 47 of 92 patients who underwent combined PCL and PLC reconstruction were evaluated as a subgroup. The PLC was reconstructed using the single fibular sling method. The patients were assessed by means of the Lysholm score, International Knee Documentation Committee (IKDC) subjective knee score, and Tegner activity score. Stability was evaluated using a KT-2000 arthrometer and Telos device. Proprioception was assessed using the Biodex System. Follow-up magnetic resonance imaging (MRI) was performed in 34 patients, and second-look arthroscopic surgery was conducted in 36 patients.

RESULTS

The minimum follow-up duration was 24 months in all patients. Clinical outcomes and posterior instability improved significantly. The mean Lysholm score improved from 56.7 ± 7.1 to 89.3 ± 7.3, the mean IKDC subjective knee score improved from 53.3 ± 9.6 to 86.2 ± 6.1, and the mean Tegner activity score was 2.5 ± 0.8 preoperatively and 5.1 ± 1.3 postoperatively (all P < .001). The mean side-to-side difference on posterior stress radiography with the Telos device improved significantly, decreasing from 12.1 ± 2.5 mm to 2.7 ± 1.3 mm (P < .001). The mean side-to-side difference on varus stress radiography was reduced from 5.9 ± 0.8 mm preoperatively to 1.3 ± 1.0 mm after combined PCL and PLC reconstruction (P < .001). Postoperative proprioception recovered to a level similar to that of the uninvolved side, and MRI and second-look arthroscopic surgery showed a high rate of complete healing and synovialization in patients who underwent either isolated PCL reconstruction or combined PLC and PCL reconstruction.

CONCLUSION

Transtibial PCL reconstruction with remnant preservation resulted in satisfactory clinical, functional, radiological, and morphological outcomes. The results of combined posterolateral rotatory instability were comparable with those for isolated PCL reconstruction with adequate PLC reconstruction.

Anatomic anterior cruciate ligament (ACL) reconstruction: a global perspective. Part 1

PURPOSE

In August 2011, orthopaedic surgeons from more than 20 countries attended a summit on anatomic anterior cruciate ligament (ACL) reconstruction. The summit offered a unique opportunity to discuss current concepts, approaches, and techniques in the field of ACL reconstruction among leading surgeons in the field.

METHODS

Five panels (with 36 panellists) were conducted on key issues in ACL surgery: anatomic ACL reconstruction, rehabilitation and return to activity following anatomic ACL reconstruction, failure after ACL reconstruction, revision anatomic ACL reconstruction, and partial ACL injuries and ACL augmentation. Panellists' responses were secondarily collected using an online survey.

RESULTS

Thirty-six panellists (35 surgeons and 1 physical therapist) sat on at least one panel. Of the 35 surgeons surveyed, 22 reported performing "anatomic" ACL reconstructions. The preferred graft choice was hamstring tendon autograft (53.1 %) followed by bone-patellar tendon-bone autograft (22.8 %), allograft (13.5 %), and quadriceps tendon autograft (10.6 %). Patients generally returned to play after an average of 6 months, with return to full competition after an average of 8 months. ACL reconstruction "failure" was defined by 12 surgeons as instability and pathological laxity on examination, a need for revision, and/or evidence of tear on magnetic resonance imaging. The average percentage of patients meeting the criteria for "failure" was 8.2 %.

CONCLUSIONS

These data summarize the results of five panels on anatomic ACL reconstruction. The most popular graft choice among surgeons for primary ACL reconstructions is hamstring tendon autograft, with allograft being used most frequently employed in revision cases. Nearly half of the surgeons surveyed performed both single- and double-bundle ACL reconstructions depending on certain criteria. Regardless of the technique regularly employed, there was unanimous support among surgeons for the use of "anatomic" reconstructions using bony and soft tissue remnant landmarks.

Basic science of anterior cruciate ligament injury and repair

Injury to the anterior cruciate ligament (ACL) is one of the most devastating and frequent injuries of the knee. Surgical reconstruction is the current standard of care for treatment of ACL injuries in active patients. The widespread adoption of ACL reconstruction over primary repair was based on early perception of the limited healing capacity of the ACL. Although the majority of ACL reconstruction surgeries successfully restore gross joint stability, post-traumatic osteoarthritis is commonplace following these injuries, even with ACL reconstruction. The development of new techniques to limit the long-term clinical sequelae associated with ACL reconstruction has been the main focus of research over the past decades. The improved knowledge of healing, along with recent advances in tissue engineering and regenerative medicine, has resulted in the discovery of novel biologically augmented ACL-repair techniques that have satisfactory outcomes in preclinical studies. This instructional review provides a summary of the latest advances made in ACL repair. Cite this article: Bone Joint Res 2014;3:20-31.

Surgical management of partial tears of the anterior cruciate ligament

PURPOSE

Partial anterior cruciate ligament (ACL) tears involving the posterolateral (PL) bundle can lead to rotatory laxity of the knee, while tears involving the anteromedial (AM) bundle result in abnormal anteroposterior laxity of the knee. In this systematic review, we examine the best evidence on the management of partial tears of the ACL.

METHODS

A comprehensive search of several databases was performed from the inception of the database to December 2011, using various combinations of keywords focusing on clinical outcomes of human patients who had partial tears of ACL and who had undergone ACL augmentation. We evaluated the methodological quality of each article using the Coleman Methodology Score.

RESULTS

Ten articles published in peer-reviewed journals were identified (392 males and 242 females), with a mean modified Coleman methodology of 66.1 ± 10.2. Only two studies compared standard ACL reconstruction and augmentation techniques. No study has a sample large enough to allow establishing guidelines. Validated and standardized proprioception assessment methods should be used to report outcomes. Imaging outcomes should be compared to functional outcomes, and a control group consisting of traditional complete ACL reconstruction should be present.

CONCLUSION

There is a need to perform appropriately powered randomized controlled trials presenting clinical outcome with homogeneous score systems to allow accurate statistical analysis. ACL augmentation technique, preserving the intact AM or PL bundle of the ACL, is encouraging but currently available evidences are too weak to support his routine use in clinical practice.

Remnant preservation is helpful to obtain good clinical results in posterior cruciate ligament reconstruction: comparison of clinical results of three techniques

Background

The purpose of the present study was to compare the clinical results of 3 posterior cruciate ligament reconstruction techniques according to the time from injury to surgery and remnant PCL status and to evaluate the efficiency of each technique.

Methods

The records of 89 patients who underwent primary PCL reconstructions with a posterolateral corner sling were analyzed retrospectively. Thirty-four patients were treated by anterolateral bundle (ALB) reconstruction with preservation of the remnant PCL using a transtibial tunnel technique in the acute and subacute stages of injury (group 1). Forty patients were treated with remnant PCL tensioning and an ALB reconstruction using the modified inlay technique in the chronic stage (group 2), and fifteen patients were treated with double-bundle reconstruction using the modified inlay technique (group 3). The double-bundle reconstruction was performed if there was a very weak or no PCL remnant.

Results

The mean side-to-side differences in posterior tibial translation on the stress radiographs were reduced from 10.1 ± 2.5 mm in group 1, 10.6 ± 2.4 mm in group 2, and 12.8 ± 3.2 mm in group 3 preoperatively to 2.3 ± 1.4 mm in group 1, 2.3 ± 1.5 mm in group 2, and 4.0 ± 2.5 mm in group 3 at the last follow-up (p < 0.001, p < 0.001, and p < 0.001, respectively). Statistical analyses revealed that group 1 and group 2 were similar in terms of side-to-side difference changes in posterior tibial translation on the stress radiographs; however, group 3 was inferior to group 1 and group 2 at the last follow-up (p = 0.022). The clinical results were not significantly different among the three groups.

Conclusions

Excellent posterior stability and good clinical results were achieved with ALB reconstruction preserving the injured remnant PCL in the acute and subacute stages and remnant PCL tensioning with ALB reconstruction in the chronic stage. The PCL injuries could be surgically corrected with different techniques depending on both the remnant PCL status and the interval between the knee trauma and operation.

Combined effects of chemical priming and mechanical stimulation on mesenchymal stem cell differentiation on nanofiber scaffolds

Functional tissue engineering of connective tissues such as the anterior cruciate ligament (ACL) remains a significant clinical challenge, largely due to the need for mechanically competent scaffold systems for grafting, as well as a reliable cell source for tissue formation. We have designed an aligned, polylactide-co-glycolide (PLGA) nanofiber-based scaffold with physiologically relevant mechanical properties for ligament regeneration. The objective of this study is to identify optimal tissue engineering strategies for fibroblastic induction of human mesenchymal stem cells (hMSC), testing the hypothesis that basic fibroblast growth factor (bFGF) priming coupled with tensile loading will enhance hMSC-mediated ligament regeneration. It was observed that compared to the unloaded, as well as growth factor-primed but unloaded controls, bFGF stimulation followed by physiologically relevant tensile loading enhanced hMSC proliferation, collagen production and subsequent differentiation into ligament fibroblast-like cells, upregulating the expression of types I and III collagen, as well as tenasin-C and tenomodulin. The results of this study suggest that bFGF priming increases cell proliferation, while mechanical stimulation of the hMSCs on the aligned nanofiber scaffold promotes fibroblastic induction of these cells. In addition to demonstrating the potential of nanofiber scaffolds for hMSC-mediated functional ligament tissue engineering, this study yields new insights into the interactive effects of chemical and mechanical stimuli on stem cell differentiation.

Promising short-term results following selective bundle reconstruction in partial anterior cruciate ligament tears

BACKGROUND

The different functions of the two anterior cruciate ligament (ACL) bundles have increased interest in tears of only one of these two bundles. The purpose of this study was to assess the outcome of selective reconstruction of an injured bundle of isolated anteromedial bundle (AMB) or posterolateral bundle (PLB) tears.

METHODS

Consecutive series of 147 ACL reconstructions was prospectively analyzed. Patients with partial ACL tears who underwent selective bundle reconstructions were studied. Stability was assessed with the Lachman, anterior-drawer and pivot-shift tests and KT-1000. Functional assessment was performed with Lysholm and Tegner questionnaires. The preoperative MRI was analyzed to detect differences from arthroscopic findings.

RESULTS

Twenty-eight patients (19%) were included. The minimum follow-up period was 30months. Eighteen had AMB and 10 PLB tears. Only 19% of their MRI's were categorized as partial ACL tears. The Lysholm score improved from 66.1/65.5 to 96.6/95.2 in the AMB/PLB groups, respectively (p<0.001). The same or no more than one level lower Tegner score was restored. The pivot-shift, Lachman and anterior-drawer tests were negative in all cases (p<0.001). Two reconstructed AMBs developed extension loss due to Cyclops lesions and were resolved surgically.

CONCLUSIONS

The technique provided excellent functional scores with normalized stability and a return to previous level of activity with a low rate of minor complications at a minimum 2.5years' follow-up. Arthroscopic examination was the most reliable tool for properly diagnosing and treating a condition observed in almost one out of every five ACL reconstructed knee in this series.

LEVEL OF EVIDENCE

Therapeutic case series; level 4.

Instrument-assisted cross fiber massage increases tissue perfusion and alters microvascular morphology in the vicinity of healing knee ligaments

Background

Ligament injuries are common clinical problems for which there are few established interventions. Instrument-assisted cross fiber massage (IACFM) was recently shown to accelerate the restoration of biomechanical properties in injured rodent knee medial collateral ligaments (MCL). The current study aimed to investigate the influence of IACFM on regional perfusion and vascularity in the vicinity of healing rodent knee MCL injuries.

Methods

Bilateral knee MCL injuries were induced in female Sprague–Dawley rats. Commencing 1 week post-injury, 1 minute of IACFM was introduced unilaterally 3 times/week for 3 weeks. The contralateral injured MCL served as an internal control. Regional tissue perfusion was assessed in vivo throughout healing using laser Doppler imaging, whereas regional microvascular morphology was assessed ex vivo via micro-computed tomography of vessels filled with contrast.

Results

IACFM had no effect on tissue perfusion when assessed immediately, or at 5, 10, 15 or 20 min following intervention (all p > 0.05). However, IACFM-treated hindlimbs had enhanced tissue perfusion when assessed 1 day following the 4th and 9th (last) treatment sessions (all p < 0.05). IACFM-treated hindlimbs also had greater perfusion when assessed 1 wk following the final treatment session (32 days post-injury) (p < 0.05). Subsequent investigation of microvascular morphology found IACFM to increase the proportion of arteriole-sized blood vessels (5.9 to <41.2 μm) in the tibial third of the ligament (p < 0.05).

Conclusions

These findings suggest IACFM alters regional perfusion and vascularity in the vicinity of healing rodent knee MCL injuries. This effect may contribute to the beneficial effect of IACFM observed on the recovery of knee ligament biomechanical properties following injury.

Partial ACL tears: anatomic reconstruction versus nonanatomic augmentation surgery

Treatment of partial anterior cruciate ligament (ACL) tears requires ACL remnant preservation. The goal of this study was to compare the outcome of anatomic reconstruction of the torn bundle with nonanatomic augmentation using the over-the-top femoral route. Fifty-two athletes (mean age, 23.3 years) with partial ACL lesions underwent anatomic reconstruction (n=26) or nonanatomic augmentation (n=26). Intraoperative damage of the healthy bundle that required a standard ACL reconstruction occurred in 2 patients in the anatomic reconstruction group. International Knee Documentation Committee (IKDC) score, Tegner score, and arthrometer evaluation were used pre-operatively and at follow-up for up to 5 years postoperatively. One failure occurred in the anatomic reconstruction group. Mean IKDC subjective score at follow-up was 88.2 ± 5.7 in the anatomic reconstruction group and 90.2 ± 4.7 in the nonanatomic augmentation group. According to the IKDC objective score at final follow-up, 96% of knees in the nonanatomic augmentation group were normal vs 87.5% in the anatomic reconstruction group. No significative differences were observed between the 2 groups at final follow-up. Anteromedial bundle reconstruction showed significantly lower IKDC subjective and objective scores and higher residual instability values as evaluated with the arthrometer compared with posterolateral bundle reconstruction (P=.017). The surgical treatment of ACL partial tears is demanding. Adapted portals, perfect control of the tunnel drilling process, and intercondylar space management are required in anatomic reconstruction. The nonanatomic augmentation technique is simpler, providing excellent durable results over time with a lower complication rate. Anteromedial bundle reconstruction is associated with a poorer outcome, especially when performed with anatomic reconstruction.

Roles of ACL remnants in knee stability

PURPOSE

This study evaluated knee laxity in anterior tibial translation and rotation following removal of anterior cruciate ligament (ACL) remnants using a computer navigation system.

METHODS

This prospective study included 50 knees undergoing primary ACL reconstruction using a navigation system. ACL remnants were classified into four morphologic types: Type 1, bridging between the roof of the intercondylar notch and tibia; Type 2, bridging between the posterior cruciate ligament and tibia; Type 3, bridging between the anatomical insertions of the ACL on the lateral wall of the femoral condyle and the tibia; and Type 4, no bridging of ACL remnants. Anterior tibial translation and rotatory laxity were measured before and after remnant resection using a navigation system at 30°, 60°, and 90° of knee flexion. The amount of change in anterior tibial translation and rotatory laxity of each type was compared among the types.

RESULTS

The different morphologic types of ACL remnants were as follows: Type 1, 15 knees; Type 2, 9 knees; Type 3, 6 knees; and Type 4, 20 knees. The amount of change in anterior tibial translation and rotatory laxity at 30° knee flexion in Type 3 was significantly larger than in the other types. There were no significant differences in either tibial translation or rotatory laxity at 60° and 90° knee flexion among the types.

CONCLUSIONS

In Type 3, ACL remnants contributed to anteroposterior and rotatory knee laxity evaluated at 30° knee flexion. The bridging point of the remnants is important to knee laxity. The Type 3 remnant should be preserved as much as possible when ACL reconstruction surgery is performed.

LEVEL OF EVIDENCE

Prognostic study, level II.

Proprioception and clinical results of anterolateral single-bundle posterior cruciate ligament reconstruction with remnant preservation

Purpose

To evaluate the clinical and radiological results and proprioception following anterolateral single-bundle posterior cruciate ligament (PCL) reconstruction with remnant preservation for PCL injury.

Materials and Methods

Twenty patients with an isolated PCL injury (16 males and 4 females) were included in this study. The mean follow-up period was 61 months (≥24 months) and the mean age of the patients was 36 years. Knee joint instability was evaluated using posterior drawer stress radiography. Knee function, level of activities, and individual satisfaction were assessed using the Lysholm knee score, Tegner activity score, and 2000 International Knee Documentation Committee (IKDC) score. Knee proprioception was assessed using an isokinetic machine.

Results

The mean ligament laxity assessed using the posterior drawer stress radiography was improved from 10.8-3.2 mm. The mean Lysholm knee score was improved from 70.0-88.9 points, and the mean Tegner activity score was improved from 2.7-6.2 points. Individual satisfaction assessed using the IKDC score was improved from 62.7-85.4 points (p<0.05). Knee proprioception was not significantly different between the treated and the uninjured knees.

Conclusions

Single-bundle PCL reconstruction with remnant preservation for PCL injury exhibited satisfactory outcomes regarding functional outcome, joint stability, and proprioception.

Preservation of remnant attachment improves graft healing in a rabbit model of anterior cruciate ligament reconstruction

PURPOSE

To determine the effect of remnant preservation on the healing of anterior cruciate ligament (ACL) tendon graft after reconstruction in an animal model.

METHODS

Fifty-two New Zealand rabbits were divided into 6 groups. Revascularization and graft healing were studied in groups 1 through 4 (n = 8 each). The biomechanical properties of the graft complex were evaluated in group 5 (n = 12). The blood flow and biomechanical characteristics of the intact ACL were evaluated in group 6 (n = 8). Both knees of each rabbit were subjected to ACL reconstruction with 2-mm grafts of Achilles tendon splits. The right knees were reconstructed with remnant preservation, whereas the remnants in the left knees were debrided. The revascularization and remodeling of grafts were evaluated at 6, 12, 18, and 24 weeks after reconstruction. Tendon-to-bone integration was investigated histomorphologically. The tensile load strengths of graft complexes were also tested.

RESULTS

The blood flow in the graft was significantly higher in the remnant-preserved group than in the remnant-debrided group (P < .01). Specifically, the blood flow of the graft with remnant preservation was markedly enhanced at 6 weeks and 12 weeks after reconstruction (P < .05). The number of CD34-positive vessels in the graft was higher in the remnant-preservation group (P < .05). The ligamentization and remodeling of the graft were improved and the collagen type III content in the graft was higher in the remnant-preserved group (P < .05). Tendon-to-bone integration was improved by remnant preservation. At 24 weeks after reconstruction, the failure load of the graft complex was significantly higher in the remnant-preserved group (23.46 ± 7.40 N) than in the remnant-debrided group (18.63 ± 4.26 N) (P < .05).

CONCLUSIONS

The preservation of the remnant attachment in ACL reconstruction improved the revascularization and remodeling of the graft and enhanced the biomechanical properties of the integrated graft.

CLINICAL RELEVANCE

Preservation of the remnant attachment may benefit healing of the tendon graft in ACL reconstruction.

Augmentation or reconstruction of PCL? A quantitative review

PURPOSE

The purpose of this quantitative review is to document effectiveness and complications of posterior cruciate ligament (PCL) surgery and compare outcomes, advantages and disadvantages of reconstructive and augmentation procedures.

METHODS

A systematic literature search was performed in PubMed, Medline, Ovid, Google Scholar and Embase databases using the combined keywords "PCL reconstruction," "PCL augmentation," "clinical outcomes" and "functional outcomes" with no limit for year of publication. Articles were included if they reported data on clinical, functional and imaging outcomes who had undergone reconstruction or augmentation of the PCL for management of PCL injuries. Two authors screened the selected articles for title, abstract and full text in accordance with predefined inclusion and exclusion criteria. The methodological quality of all articles was assessed by two authors according to the Coleman methodology score. The critical appraisal was made using the Physiotherapy Evidence Database (PEDro) scale.

RESULTS

A total of 34 studies, 22 retrospective, 9 prospective and 5 were randomized control trials were included by full text. The modified Coleman methodology score averaged 70.8 (SD 6.5), median 73 (range from 60 to 82). At IKDC assessment, the average rate of normal (A) and nearly normal (B) outcomes was 89.8% (SD 4.2) (from 85 to 93%; median 91.4) after PCL augmentation and 80.1% (SD 12.4) after PCL reconstruction (from 57.2 to 100%; median 81.8 %) were rated as normal (A) and nearly normal (B). The average Lysholm Knee Scores after PCL augmentation were 93.1 points (SD 1.9) and ranged from 82.1 to 94.2 (median 90.5) after PCL reconstruction. The KT 1000 difference improved from an average preoperative difference of 8.8 mm (SD 0.9) to an average postoperative of 2.1 mm (SD 0.6) after PCL augmentation (average improvement of 6.7 mm (SD 4.7)) and from 8.2 (SD 3.6) to 2.3 mm (SD 2.0) (average improvement of 5.9 mm SD 4.2) after PCL reconstruction. Postoperatively, the Telos stress radiographic side to side difference averagely improved by 8.6 mm (SD 6.1) after PCL augmentation, from 11.1 mm (SD 1.4) to 2.5 mm (SD 0.4), and by 8.0 mm (SD 5.7) after PCL reconstruction, from 11.5 mm (SD 2.2) to 3.5 mm (SD 1.3).

CONCLUSIONS

Augmentation and reconstruction procedures are grossly equivalent, but more data examining the long-term functional status, recovery to preinjury daily and sport activities and occurrence of degenerative changes are needed.

LEVEL OF EVIDENCE

IV.

Anterior cruciate ligament reconstruction in partial tear: selective anteromedial bundle reconstruction conserving the posterolateral remnant versus single-bundle anatomic ACL reconstruction: preliminary 1-year results of a prospective randomized study

INTRODUCTION

Partial tears of the anterior cruciate ligament (ACL) are frequent. Conserving ACL remnants is central to the concept of anatomic, biomechanical and biological reconstruction. The interest of such conservation remains theoretical. The present hypothesis was that selective anteromedial (AM) bundle reconstruction is preferable to the standard single-bundle reconstruction in partial ACL tear.

MATERIALS AND METHODS

A multicenter prospective randomized study recruited 54 partial ACL tears operated on either by selective AM bundle reconstruction (Group 1, n=29) or by standard anatomic single-bundle reconstruction (Group 2, n=25). All patients were clinically assessed on subjective and objective IKDC, Lysholm and KOOS scores, with a minimum 12 months' follow-up. Comparative pre- to postoperative anterior laxity was measured on the Rolimeter(®) device, with statistical analysis of results.

RESULTS

There were no significant preoperative differences between the two groups. All patients were followed-up at 6 months and 1 year. Mean subjective IKDC scores for groups 1 and 2 respectively were 55.8 and 56.8 preoperatively versus 86.2 and 85.7 at 1 year; Lysholm scores were 69.9 and 71.1 versus 90.9 and 91.8. These inter-group differences were non-significant. Differential laxity for groups 1 and 2 respectively was 5.0mm (range, 2-10) and 5.1mm (2-12) preoperatively (P=0.73), versus 1.2mm and 1.9 mm postoperatively (P=0.03).

DISCUSSION AND CONCLUSION

In partial ACL tear, selective AM bundle reconstruction conserving the posterolateral bundle remnant provides clinical results comparable to the standard single-bundle technique, with better control of anterior laxity. Longer follow-up, however, will be needed to compare evolution in anterior and rotational laxity and in subjective results over time.

Partial ACL reconstruction with preservation of the posterolateral bundle

INTRODUCTION

Over the past decade, our understanding of the anterior cruciate ligament (ACL) has evolved considerably. Based on this knowledge, ACL reconstruction techniques have changed and selective reconstruction procedures have been developed for partial tears. Our hypothesis was that stability and function can be restored to the knee with selective bundle reconstruction of partial ACL tears and preservation of the residual fibers.

MATERIALS AND METHODS

This was a multicenter retrospective study of 168 partial reconstructions of the anteromedial (AM) bundle of the ACL with preservation of the posterolateral (PL) bundle. All patients underwent a clinical evaluation based on the objective and subjective IKDC scores and the Lysholm score after a mean follow-up of 26 months (12-59 months). Preoperative and postoperative instrumental measurement of knee laxity was performed by arthrometer and/or by (Telos(®)) stress radiography. Statistical analysis and comparison was performed between pre- and postoperative results.

RESULTS

The preoperative and postoperative subjective IKDC scores were 63.7 and 90.5 at the final follow-up respectively (P<0.001). The preoperative and postoperative Lysholm scores were 80 and 95.5 respectively (P<0.001). Preoperatively, most patients were classified C on the objective IKDC score. At the final follow-up 92% of the patients were classified A or B (P<0.001). Differential preoperative laxity was 5.5mm (range: 0-14 mm) and 1.1mm (range: 0-4mm) at the final follow-up (P<0.00001).

DISCUSSION AND CONCLUSION

Our study confirms that selective reconstruction of the AM bundle of the ACL with preservation of the PL bundle restores stability and function to the knee. Special attention should be paid to the size of the graft used to avoid excess tissue in the intercondylar notch.