Bone tunnel enlargement after anterior cruciate ligament replacement

Assessment of the advantages and limitations of an innovative silk fibroin scaffold for the reconstruction of the anterior cruciate ligament with preclinical in vitro and in vivo evaluations

The gold standard treatment in anterior cruciate ligament (ACL) reconstruction involves autologous tissue transplantation, but this can have complications. Artificial grafts are an alternative, but the best option is debated. This study aimed to assess the biocompatibility and integration of a silk fibroin textile prosthesis (SF-TP) with peri-implant bone tissue and the native ACL. Twenty-six sheep underwent ACL reconstruction with SF-TP or autologous femoral fascia lata (FFL). Sheep were divided into two groups (3 and 6 months) and retrieved joints processed for histological, morphometrical and mechanical analysis. In vitro, SF-TP showed no cytotoxicity and good cell interaction up to 14 days. Histology revealed fibro-vascular tissue around SF-TP, with a progressive attempt of ligamentous-like tissue formation at 6 months. However, SF-TP group had higher joint damage scores. Micro-CT showed tunnel enlargement in SF-TP group, while FFL group had a decrease. SF-TP reconstructions had lower stiffness and strength (44 % and 64 % decrease) than those of autologous FFL reconstruction and often failed by pull-out from the bone tunnel due to tunnel enlargement. These results indicate poor osteointegration and graft motion with SF-TP, leading to joint damage/bone resorption and reduced mechanical competence. These results do not support the use of SF-TP for ACL reconstruction.

Gradual stabilization and narrowing of bone tunnels following primary anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study is to dynamically assess variations in tunnel diameters following anterior cruciate ligament reconstruction (ACLR) and investigate correlations with patient-reported outcomes (PROs) and graft maturity based on signal-to-noise quotient (SNQ).

METHODS

Tunnel diameter and tunnel position were measured using three-dimensional models derived from computed tomography (CT) data. Postoperative graft maturity and integration were evaluated using magnetic resonance imaging (MRI). Clinical outcomes were assessed through PROs, which included the International Knee Documentation Committee Subjective Knee Evaluation Form, Knee Injury and Osteoarthritis Outcome Scores and Lysholm scores. The correlation between tunnel enlargement extent, PROs and SNQ values, as well as correlations between confounding factors, tunnel diameter differences and SNQ were analyzed.

RESULTS

A total of 73 participants underwent primary ACLR and scheduled follow-ups. At the segment of the articular aperture, the femoral tunnel was enlarged by 32.3% to 10.4 ± 1.6 mm (p < 0.05), and the tibial tunnel was widened by 17.2% to 9.6 ± 1.2 mm (p < 0.05) at the 6-month follow-up. At 1 year postoperatively, diameters at the articular aperture were not further increased on the femoral (n.s.) and tibial (n.s.) sides. In early postoperative follow-up, the femoral tunnel was anteriorly and distally shifted, coupled with posterior and lateral deviation involving the tibial side, exhibiting minimal migration at 1-year follow-up. The degree of tunnel widening was not correlated with PROs and SNQ values. Age, gender, body mass index (BMI), time from surgery to follow-up, concomitant injuries and autograft type were not correlated with tunnel diameter differences and SNQ.

CONCLUSIONS

The femoral and tibial bone tunnels exhibited eccentrical widening and gradually stabilized at 1 year following ACLR. Furthermore, the enlarged bone tunnels were not correlated with unsatisfied PROs and inferior graft maturity.

LEVEL OF EVIDENCE

Level IV.

Lateral extra-articular tenodesis does not enhance ACL graft healing, however, does reduce graft tunnel widening

PURPOSE

The study hypothesized that the addition of lateral extra-articular tenodesis (LEAT) in anterior cruciate ligament reconstruction (ACLR) had a significant effect on ACL graft healing.

METHODS

A total of 80 patients were divided into two cohorts matched for gender, age, body mass index, time from surgery to post-operative MRI and graft diameter. Forty patients underwent ACL reconstruction alone, while 40 underwent ACLR in addition to LEAT. Patients underwent a magnetic resonance imaging scan at 12 months post-surgery; tunnel apertures were measured using multiplanar reformation, graft healing was assessed using signal-to-noise quotient (SNQ) in three regions of interest and finally graft maturity and integration were classified using the Howell and Ge scale, respectively. In addition, clinical evaluation and patient-reported outcome measures were collected.

RESULTS

The mean femoral tunnel widening at 12 months post-surgery was 39.8 ± 14.0% in the ACLR + LEAT group and 55.2 ± 12.7% in the ACLR alone group (p < 0.05). The mean tibial tunnel widening was 29.3 ± 12.7% in the ACLR + LEAT group and 44.4 ± 12.1% in the ACLR group (p < 0.05). The mean adjusted graft SNQ was 9.0 ± 14.9 in the ACLR + LEAT group and 9.5 ± 11.4 in the ACLR group (n.s.).

CONCLUSION

At 1 year post-operatively, we noted significantly less femoral and tibial tunnel widening in the ACLR + LEAT group. LEAT did not result in a statistically significant effect on graft healing.

LEVEL OF EVIDENCE

Level III.

Computational modelling of the graft-tunnel interaction in single-bundle ACL reconstructed knee

OBJECTIVES

Tunnel enlargement and graft failure are common complications associated with ACL reconstruction. The mechanical interaction between the graft and the tunnel aperture may play a more important role. This study aims to evaluate graft position within femoral tunnel and the graft force under external loads.

METHODS

An FE model of the femur-graft-tibia complex was constructed from CT images of an anatomically reconstructed knee specimen. The model was subjected to kinematics of passive flexion extension, anterior/posterior translation, internal/external rotation and valgus kinematics, which were collected from experimental testing. Graft shift and rotation of graft-tunnel contact region during flexion/extension and external loadings were recorded and compared to experimental measurements.

RESULTS

Model showed that the graft shifted in the femoral tunnel during flexion and under external loads. The graft-tunnel contact area rotated by up to 55° during flexion from full extension to 90° of extension implying that the so-called "wiper effect" occurs during most of flexion angles.

CONCLUSIONS

Different regions of the femoral tunnel aperture, particularly the anterior region, were under significantly more contact force from the graft than other areas of the aperture during the anterior translation test, potentially leading to femoral tunnel enlargement to the anterior side of the aperture.

Beneficial Effect of Curved Dilator System for Femoral Tunnel Creation in Preventing Femoral Tunnel Widening after Anterior Cruciate Ligament Reconstruction

Backgrounds and objectives: A prevalent concern in anterior cruciate ligament (ACL) reconstruction is postoperative tunnel widening. We hypothesized that employing a curved dilator system (CDS) for femoral tunnel creation can reduce this widening after ACL reconstruction compared to the use of a conventional rigid reamer. Materials and Methods: A retrospective study was conducted involving 56 patients who underwent primary ACL reconstruction between January 2012 and July 2013. The patients were categorized into two groups: the reamer group (n = 28) and CDS group (n = 28). All participants were followed up for a minimum of 2 years. Clinical assessment included the Lachman test and pivot-shift test, and the Lysholm score and subjective International Knee Documentation Committee scores. Radiographic evaluation covered the tunnel widening rate, represented as the ratio of the tunnel diameter 2 years after surgery to the tunnel diameter immediately after surgery, and the ratio (A/B) of femoral tunnel (A) to tibial tunnel (B) diameters at respective time points. Results: No significant disparities were found between the two groups in terms of clinical outcomes. However, the reamer group exhibited a greater femoral tunnel widening rate compared to the CDS group (reamer group vs. CDS group: 142.7 ± 22.0% vs. 128.0 ± 19.0% on the anteroposterior (AP) radiograph and 140.8 ± 14.2% vs. 122.9 ± 13.4% on the lateral radiograph; all p < 0.05). Two years post-operation, the A/B ratio rose in the reamer group (0.96 ± 0.05→1.00 ± 0.05 on the AP radiograph and 0.94 ± 0.03→1.00 ± 0.0.04 on the lateral radiograph; all p < 0.05), while it decreased in the CDS group (0.99 ± 0.02→0.96 ± 0.05 on the AP radiograph and 0.97 ± 0.03→0.93 ± 0.06 on the lateral radiograph; all p < 0.05). Conclusion: The use of CDS for femoral tunnel creation in primary ACL reconstruction provides a potential advantage by limiting tunnel widening compared to the conventional rigid-reamer approach.

Combined press-fit and extracortical fixation in patellar tendon anterior cruciate ligament reconstruction results in reliable graft fixation and early bone block incorporation

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction with bone-patellar-tendon-bone (BPTB) autograft has the potential biological advantage of direct bone-to-bone healing over soft tissue grafts. The primary aim of this study was to investigate possible graft slippage and therefore fixation strength in a modified BPTB autograft technique with suspensory fixation on both sides for primary ACL reconstruction until bony integration takes place.

METHODS

Twenty-one patients undergoing primary ACL reconstruction with a modified BPTB autograft (bone-on-bone (BOB) technique) between August 2017 and August 2019 were included in this prospective study. A computed tomography (CT) scan of the affected knee was performed directly postoperatively, as well as 3 months postoperatively. Examiner-blinded parameters for graft slippage, early tunnel widening, bony incorporation, as well as remodeling of the autologous refilled patellar harvest site were investigated.

RESULTS

A series of 21 patients treated with a BPTB autograft with this technique underwent two CT investigations. Comparison of CT scans showed no bone block displacement and therefore no graft slippage in the patient cohort. Only one patient showed signs of early tunnel enlargement. Radiological bone block incorporation took place showing bony bridging of the graft to the tunnel wall in 90% of all patients. Furthermore, 90% showed less than 1 mm bone resorption of the refilled harvest site at the patella.

CONCLUSIONS

Our findings suggest graft fixation stability and reliability of anatomic BPTB ACL reconstruction with a combined press-fit and suspensory fixation technique by absence of graft slippage within the first 3 months postoperatively.

Anatomical Tissue Engineering of the Anterior Cruciate Ligament Entheses

The firm integration of anterior cruciate ligament (ACL) grafts into bones remains the most demanding challenge in ACL reconstruction, since graft loosening means graft failure. For a functional-tissue-engineered ACL substitute to be realized in future, robust bone attachment sites (entheses) have to be re-established. The latter comprise four tissue compartments (ligament, non-calcified and calcified fibrocartilage, separated by the tidemark, bone) forming a histological and biomechanical gradient at the attachment interface between the ACL and bone. The ACL enthesis is surrounded by the synovium and exposed to the intra-articular micromilieu. This review will picture and explain the peculiarities of these synovioentheseal complexes at the femoral and tibial attachment sites based on published data. Using this, emerging tissue engineering (TE) strategies addressing them will be discussed. Several material composites (e.g., polycaprolactone and silk fibroin) and manufacturing techniques (e.g., three-dimensional-/bio-printing, electrospinning, braiding and embroidering) have been applied to create zonal cell carriers (bi- or triphasic scaffolds) mimicking the ACL enthesis tissue gradients with appropriate topological parameters for zones. Functionalized or bioactive materials (e.g., collagen, tricalcium phosphate, hydroxyapatite and bioactive glass (BG)) or growth factors (e.g., bone morphogenetic proteins [BMP]-2) have been integrated to achieve the zone-dependent differentiation of precursor cells. However, the ACL entheses comprise individual (loading history) asymmetric and polar histoarchitectures. They result from the unique biomechanical microenvironment of overlapping tensile, compressive and shear forces involved in enthesis formation, maturation and maintenance. This review should provide a road map of key parameters to be considered in future in ACL interface TE approaches.

Femoral Tunnel Position Affects Postoperative Femoral Tunnel Widening after Anterior Cruciate Ligament Reconstruction with Tibialis Anterior Allograft

This study aims to identify potential factors for both femoral and tibial tunnel widening (TW) and to investigate the effect of TW on postoperative outcomes after anterior cruciate ligament (ACL) reconstruction with a tibialis anterior allograft. A total 75 patients (75 knees) who underwent ACL reconstruction with tibialis anterior allografts were investigated between February 2015 and October 2017. TW was calculated as the difference in tunnel widths between the immediate and 2-year postoperative measurements. The risk factors for TW, including demographic data, concomitant meniscal injury, hip-knee-ankle angle, tibial slope, femoral and tibial tunnel position (quadrant method), and length of both tunnels, were investigated. The patients were divided twice into two groups depending on whether the femoral or tibial TW was over or less than 3 mm. Pre- and 2-year follow-up outcomes, including the Lysholm score, International Knee Documentation Committee (IKDC) subjective score, and side-to-side difference (STSD) of anterior translation on stress radiographs, were compared between TW ≥ 3 mm and TW < 3 mm. The femoral tunnel position depth (shallow femoral tunnel position) was significantly correlated with femoral TW (adjusted R² = 0.134). The femoral TW ≥ 3 mm group showed greater STSD of anterior translation than the femoral TW < 3 mm group. The shallow position of the femoral tunnel was correlated with the femoral TW after ACL reconstruction using a tibialis anterior allograft. A femoral TW ≥ 3 mm showed inferior postoperative knee anterior stability.

Tunnel Management in Revision Anterior Cruciate Ligament Reconstruction: Current Concepts

Bone tunnel-related complications are frequently encountered during revision anterior cruciate ligament reconstruction (ACLR). Issues with tunnel positioning, enlargement, containment, and hardware interference may complicate surgery and compromise outcomes. As a result, several strategies have emerged to address these issues and optimize results. However, a systematic, unified approach to tunnel pathology in revision ACLR is lacking. The purpose of this review is to highlight the current state of the literature on bone tunnel complications and, although extensive literature on the subject is lacking, present an updated approach to the evaluation and management of tunnel-related issues in revision ACLR.

Eccentrically widened bone tunnels after all-inside anterior cruciate ligament reconstruction: a computed tomography and three-dimensional model-based analysis

PURPOSE

To evaluate the extent of tunnel widening after anterior cruciate ligament reconstruction (ACLR) using the all-inside technique and to establish its correlation with patient-reported clinical outcomes and femoral graft bending angle (GBA).

METHODS

Tunnel widening was evaluated using computed tomography (CT)-based three-dimensional (3D) models, and the femoral GBA was directly measured on CT images using the Picture Archiving and Communication System (PACS) software. Clinical follow-up was routine procedure, and patient-reported clinical outcomes mainly included International Knee Documentation Committee (IKDC), Lysholm, and Knee Injury and Osteoarthritis Outcome Scores (KOOS) scores, and subjective knee stability assessment.

RESULTS

Fifty-two patients received standard all-inside ACLR, with a median follow-up of 6 months. Reconstructed anterior cruciate ligaments (ACLs) were scanned during the first 3 days and 6 months after surgery. On both the femoral and tibial sides, bone tunnels were most significantly enlarged at the articular aperture segment; the femoral tunnel was 9.2 ± 1.3 mm postoperatively and was significantly enlarged by 32% to a mean tunnel diameter of 12.1 ± 2.0 mm at 6 months after surgery. Moreover, the extent of tunnel enlargement gradually decreased as the measured levels approached those of the bone cortex. The femoral tunnel center was shifted into the anterior and distal direction, and the tibial tunnel center was shifted into the posterior and lateral direction. Additionally, the mean femoral GBA was 105.9° ± 8.1° at the 6-month follow-up. Tunnel enlargement and GBA were not significantly correlated with patient-reported outcomes.

CONCLUSIONS

Femoral and tibial tunnels were significantly greater and eccentrically shifted at the 6-month follow-up after all-side ACLR. However, the extent of tunnel widening does not markedly affect the short-term clinical outcomes. Meanwhile, the femoral GBA was not significantly correlated with femoral tunnel widening or patient-reported outcomes. Although the tunnel widening following all-inside ACLR was not associated with clinical outcomes, it potentially caused difficulties in revision ACLR.

LEVEL OF EVIDENCE

Level IV.

Descriptive Characteristics and Outcomes of Patients Undergoing Revision Anterior Cruciate Ligament Reconstruction With and Without Tunnel Bone Grafting

BACKGROUND

Lytic or malpositioned tunnels may require bone grafting during revision anterior cruciate ligament reconstruction (rACLR) surgery. Patient characteristics and effects of grafting on outcomes after rACLR are not well described.

PURPOSE

To describe preoperative characteristics, intraoperative findings, and 2-year outcomes for patients with rACLR undergoing bone grafting procedures compared with patients with rACLR without grafting.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 1234 patients who underwent rACLR were prospectively enrolled between 2006 and 2011. Baseline revision and 2-year characteristics, surgical technique, pathology, treatment, and patient-reported outcome instruments (International Knee Documentation Committee [IKDC], Knee injury and Osteoarthritis Outcome Score [KOOS], Western Ontario and McMaster Universities Osteoarthritis Index, and Marx Activity Rating Scale [Marx]) were collected, as well as subsequent surgery information, if applicable. The chi-square and analysis of variance tests were used to compare group characteristics.

RESULTS

A total of 159 patients (13%) underwent tunnel grafting-64 (5%) patients underwent 1-stage and 95 (8%) underwent 2-stage grafting. Grafting was isolated to the femur in 31 (2.5%) patients, the tibia in 40 (3%) patients, and combined in 88 patients (7%). Baseline KOOS Quality of Life (QoL) and Marx activity scores were significantly lower in the 2-stage group compared with the no bone grafting group (P≤ .001). Patients who required 2-stage grafting had more previous ACLRs (P < .001) and were less likely to have received a bone-patellar tendon-bone or a soft tissue autograft at primary ACLR procedure (P≤ .021) compared with the no bone grafting group. For current rACLR, patients undergoing either 1-stage or 2-stage bone grafting were more likely to receive a bone-patellar tendon-bone allograft (P≤ .008) and less likely to receive a soft tissue autograft (P≤ .003) compared with the no bone grafting group. At 2-year follow-up of 1052 (85%) patients, we found inferior outcomes in the 2-stage bone grafting group (IKDC score = 68; KOOS QoL score = 44; KOOS Sport/Recreation score = 65; and Marx activity score = 3) compared with the no bone grafting group (IKDC score = 77; KOOS QoL score = 63; KOOS Sport/Recreation score = 75; and Marx activity score = 7) (P≤ .01). The 1-stage bone graft group did not significantly differ compared with the no bone grafting group.

CONCLUSION

Tunnel bone grafting was performed in 13% of our rACLR cohort, with 8% undergoing 2-stage surgery. Patients treated with 2-stage grafting had inferior baseline and 2-year patient-reported outcomes and activity levels compared with patients not undergoing bone grafting. Patients treated with 1-stage grafting had similar baseline and 2-year patient-reported outcomes and activity levels compared with patients not undergoing bone grafting.

Influence of hamstring tendon and bone-patellar tendon-bone autografts on worsened patient reported outcome measurements in revision anterior cruciate ligament reconstruction: Comparing outcomes between primary and revision reconstructions

Background

This study aimed to compare the clinical outcomes and patient reported outcome measurement scales (PROMs) between hamstring tendon (HT) or bone-patellar tendon-bone (BTB) grafts in each primary and revision anterior cruciate ligament (ACL) reconstruction. Additionally, the clinical outcomes and PROMs between primary and revision surgeries were compared.

Methods

A total of 150 patients (109 primary and 41 revision ACL reconstructions) were enrolled and followed up for an average of 3.9 years (2 years minimum). Knee injury and osteoarthritis outcome scores (KOOS) were examined as PROMs. Side-to-side differences of anterior knee laxity were assessed using KT-1000 and were recorded at the final follow-up. After categorizing patients into HT and BTB reconstruction groups, regression analysis was performed to determine the relationship between revision surgery and changes in KOOS.

Results

In patients who underwent primary surgery, there was no significant difference in side-to-side differences of anterior laxity and KOOS between HT and BTB grafts. In those who underwent revision surgery, BTB grafts had a higher KOOS for activities of daily living (ADL) than HT grafts (p = 0.032). Comparing primary and revision surgeries, postoperative side-to-side differences of anterior laxity in the revision group were significantly larger than those in the primary group (p = 0.001). The KOOS for sports after overall revision reconstruction was significantly lower than that after primary reconstruction (p = 0.026). Comparing the KOOS after dividing all patients into HT and BTB reconstruction groups, in the HT reconstruction group, postoperative KOOS results were not different in any subscale from BTB grafts. In contrast, the KOOS for sports (p = 0.008) and QOL (p = 0.039) were significantly lower in revision surgery than in primary surgery. Furthermore, regression analysis including multiple confounders in the HT reconstruction group showed revision surgery using HT graft was correlated with worsened KOOS for symptoms (p = 0.012) and sports (p = 0.010). Revision surgery using BTB graft was not correlated with decreased KOOS.

Conclusions

There were no differences between the clinical outcome and KOOS in primary and revision surgery, except for ADL scores following revision ACL reconstruction using BTB graft. Side-to-side difference of anterior laxity and KOOS for sports following revision ACL reconstruction were inferior to those following primary ACL reconstruction.Furthermore, revision ACL reconstruction using HT grafts were correlated with low scores in KOOS for symptoms and sports, while there was no difference of anterior laxity between BTB and HT grafts in revision surgery.

Tibial graft fixation methods and bone tunnel enlargement: A comparison between the TensionLoc implant system and the double-spike plate

Background/objective

TensionLoc (Arthrex, Naples, Florida, USA), a tibial graft fixation system for anterior cruciate ligament (ACL) reconstruction, is expected to apply the preoperatively determined level of graft tension and allow setting of lower initial tension. Considering its mechanism, we hypothesised that TensionLoc would prevent postoperative bone tunnel enlargement (TE) through fixation with lower initial tension. Therefore, the present study aimed to compare TE between ACL reconstructions using the double-spike plate (DSP; Smith and Nephew, Andover, Massachusetts) and TensionLoc implant system.

Methods

A total of 40 patients who underwent anatomical single-bundle ACL reconstruction with a hamstring tendon graft were retrospectively analysed. In the group in which DSP and screw were used, the initial graft tension was set to 40 N at 20° of knee flexion (group D). In the other group in which TensionLoc was used, the initial graft tension was set to 30 N at 20° of knee flexion (group T). Both groups included 20 patients each. Tunnel areas were measured using computed tomography images at one week and three months after surgery, and the TE ratio was calculated according to the following equation: TE ratio (%) = (tunnel area at three months after surgery - tunnel area at one week after surgery)/tunnel area at one week after surgery × 100.

Results

The femoral TE ratios were significantly higher in group T (80.5% ± 28.8%) than in group D (45.5% ± 34.6%) (p = 0.001). However, the tibial TE ratios did not significantly differ between the two groups.

Conclusion

Compared with ACL reconstruction using DSP and screw, ACL reconstruction using TensionLoc fixed the graft with lower initial tension but showed greater femoral TE and restricted knee extension in the early postoperative period.

Larger Prior Tibial Tunnel Size Is Associated with Increased Failure Risk following Revision Anterior Cruciate Ligament Reconstruction

We hypothesize that larger prior tunnel size is associated with an increased risk of failure of single-stage revision anterior cruciate ligament reconstruction (ACLR) as defined by the performance of a re-revision (third) ACLR on the index knee. Retrospective review identified 244 patients who underwent single-stage revision ACLR at a single center with available preoperative radiographs. Patient and surgical factors were extracted by chart review. The maximum diameter of the tibial tunnel was measured on lateral radiographs and the maximum diameter of the femoral tunnel was measured on anteroposterior radiographs. Record review and follow-up phone calls were used to identify failure of the revision surgery as defined by re-revision ACLR on the index knee. One hundred and seventy-one patients (70%) were reviewed with a mean of 3.9 years follow-up. Overall, 23 patients (13.4%) underwent re-revision surgery. Mean tibial tunnel size was 12.6 ± 2.8 mm (range: 5.7-26.9 mm) and mean femoral tunnel size was 11.7 ± 2.8 mm (range: 6.0-23.0 mm). Re-revision risk increased with tibial tunnel size. Tibial tunnels 11 mm and under had a re-revision risk of 4.2%, while tunnels > 11 mm had a risk of 17.1% (relative risk: 4.1, p = 0.025). No significant association between femoral tunnel size and re-revision risk was noted. Patients with prior tibial tunnels > 11mm in diameter at revision surgery had significantly increased risk of re-revision ACLR. Further studies are needed to explore the relationship between prior tunnel size and outcomes of revision ACLR.

ACL graft with extra-cortical fixation rotates around the femoral tunnel aperture during knee flexion

PURPOSE

An understanding of the behavior of a new ACL graft in the femoral tunnel during knee motion and external loading can provide information pertinent to graft healing, tunnel enlargement, and graft failure. The purpose of the study was to measure the percentage of the tunnel filled by the graft and determine the amount and location of the graft-tunnel contact with knee motion and under external knee loads.

METHODS

Single bundle anatomical ACL reconstruction was performed on six cadaveric knees. Specimens were positioned with a robotic testing system under: (1) passive flexion-extension, (2) 89-N anterior and posterior tibial loads, (3) 5-N m internal and external torques, and (4) 7-N m valgus moment. The knees were then dissected, repositioned by the robot and the geometry of the femoral tunnel and graft were digitized by laser scanning. The percentage of tunnel filled and the contact region between graft and tunnel at the femoral tunnel aperture were calculated.

RESULTS

The graft occupies approximately 70% of the femoral tunnel aperture and anterior tibial loading tended to reduce this value. The graft contacted about 60% of the tunnel circumference and the location of the graft-tunnel contact changed significantly with knee flexion.

CONCLUSION

This study found that the graft tends to rotate around the tunnel circumference during knee flexion-extension and contract under knee loading. The "windshield-wiper" and "bungee cord" effect may contribute to femoral tunnel enlargement, affect graft healing, and lead to graft failure. There can be a considerable motion of the graft in the tunnel after surgery and appropriate rehabilitation time should be allowed for graft-tunnel healing to occur. To reduce graft motion, consideration should be given to interference screw fixation or a graft with bone blocks, which may allow an earlier return to activity.

Influence of Graft Bending Angle on Femoral Tunnel Widening After Double-Bundle ACL Reconstruction: Comparison of Transportal and Outside-In Techniques

Background:

Previous studies have suggested that increased mechanical stress due to acute graft bending angle (GBA) is associated with tunnel widening and graft failure after anterior cruciate ligament (ACL) reconstruction. Few studies have compared the GBA between the outside-in (OI) and the transportal (TP) techniques.

Purpose:

To evaluate the influence of GBA on clinical outcomes and tunnel widening after ACL reconstruction with OI versus TP technique.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Included in the study were 56 patients who underwent double-bundle ACL reconstruction (n = 28 in the OI group and n = 28 in the TP group). Clinical outcomes (Lysholm, International Knee Documentation Committee, Tegner score, and knee laxity) 1 year postoperatively were evaluated. Computed tomography scans at 5 days and 1 year postoperatively were used for imaging measurements, and the femoral tunnel was divided into the proximal third, middle, and aperture sections. The GBA and cross-sectional area (CSA) were measured using image analysis software and were compared between groups. A correlation analysis was performed to determine if the GBA affected clinical outcomes or tunnel widening.

Results:

No significant difference was observed in clinical outcomes between the groups. The GBA of both the anteromedial (AM) and posterolateral bundles were more acute in the OI group compared with the TP group (P < .05). The CSA at the AM tunnel aperture increased significantly in the OI group (84.2% ± 64.3%) compared with the TP group (51.4% ± 36.7%) (P = .04). However, there were no differences in the other sections. In the Pearson correlation test, GBA was not correlated with tunnel widening or clinical outcomes.

Conclusion:

Regardless of technique, the GBA did not have a significant influence on tunnel widening or clinical outcomes. Considering a wider AM tunnel aperture, a more proximal and posterior AM tunnel position might be appropriate with the OI technique.

[Lengths of the fixed loop and the adjustable loop in the coarse bone tunnel were compared to influence the widening of the femoral bone tunnel and the function of the knee joint]

OBJECTIVE

To evaluate the effects of two different femoral cortical suspension devices (fixation loop and adjustable loop) on tunnel widening and knee function in patients following anterior cruciate ligament reconstruction for 12 months.

METHODS

A total of 60 patients who had undergone anterior cruciate ligament reconstruction were included in this study. According to the length of the loop(n)[n= total length of loop-(total length of femoral tunnel-total length of coarse tunnel)] in the rough bone tunnel, the patients were divided into A (adjustable loop was 0 mm in the coarse bone tunnel), B (fixation loop was greater than 0 mm and less than or equal to 10 mm in the coarse bone tunnel) and C (fixation loop was greater than 10 mm in the coarse bone tunnel) groups, of which 11 cases were in group A, 27 cases in group B and 22 cases in group C. In the three-dimensional reconstruction of the knee joint with multi-slice spiral CT, the widening of the bone tunnel in the three groups was compared. At the same time, IKDC, Lysholm and Tegner scores of the patients in the three groups were compared.

RESULTS

There were differences in the widening degree of the femoral canal among groups A, B and C, and the median difference of the widening degree of the femoral tunnel 12 months and immediately after the surgery was A < B < C. The difference of femoral canal widening in group A was significantly different from that in groups B and C (P < 0.05).According to the linear regression the relationship between the difference of the width of the femoral canal and the change of the length (n) of the loop in the coarse canal, it was found that there was a linear relationship between the value of n and the difference of the width of the bone canal. With the increase of the value of n, the difference of the width of the bone canal gradually became larger. The median difference of the width of the middle and superior tunnel was negative, while the median difference of the width of the middle and inferior tunnel was positive. During the follow-up, we found that there were no statistical differences in IKDC, Lysholm and Tegner scores among the three groups one year after surgery (P > 0.05).

CONCLUSION

Twelve months after surgery, compared with group B (fixed loop group) and group C (fixed loop group), group A (adjustable loop group) had less bone tunnel widening.In groups A, B and C, as the length of the loop in coarse bone tunnel gradually increased, the width of bone tunnel became more significant. At the end of 12 months follow-up after anterior cruciate ligament reconstruction, the medial and inferior femoral tunnel was significantly wider than immediately after surgery, and the medial and superior femoral tunnel had gradually begun to undergo tendon-bone healing. There was no significant difference in knee function scores among groups A, B, and C in the follow-up 12 months after surgery.

No tunnel widening following arthroscopic anatomical reconstruction of the lateral ankle ligaments

INTRODUCTION

Arthroscopic anatomical reconstruction of the lateral ankle ligaments is an emerging technique for treating chronic ankle instability. One of the known complications of arthroscopic anterior cruciate ligament reconstruction is tunnel widening; this makes revision more complicated. The aim of this study was to look for tunnel widening in the postoperative course of arthroscopic ankle ligament reconstruction. We hypothesized that significant widening of the bone tunnels is present 1 year after anatomical ankle ligament reconstruction.

MATERIALS AND METHODS

Twenty-one patients who underwent arthroscopic anatomical reconstruction of the lateral ankle ligaments with a gracilis graft were included prospectively. A CT-scan with 1-mm thick slices with multiplanar reconstruction was done 1 year after the surgery. The size and shape of the tunnels was analyzed, and the ratio of the preoperative to postoperative diameter was calculated. Based on this ratio, the tunnels were given a grade as described by Struewer. Tunnel widening was defined as a grade III tunnel, thus a ratio ≥ 1.3. The tunnel shape was classified as described by Peyrache as cone type, cavity type, line type.

RESULTS

None of the tunnels had widened 1 year after arthroscopic anatomical reconstruction of the lateral ankle ligaments. At the fibula, 81% of tunnels were grade I and 19% were grade II; 57% were cone type and 43% were line type. At the talus, 86% of tunnels were grade I and 14% were grade II. All were line type. At the calcaneus, 86% of tunnels were grade I and 14% were grade II; 57% were cone type and 43% were line type.

DISCUSSION

The main finding of this study was the absence of tunnel widening 1 year after arthroscopic reconstruction of the lateral ankle ligaments.

LEVEL OF EVIDENCE

IV; retrospective study.

Feasibility study of early prediction of postoperative MRI findings for knee stability after anterior cruciate ligament reconstruction

Background

At present, the most effective and mature treatment after ACL injury and tear is ACL reconstruction, but the rehabilitation process after ACL reconstruction that is very long, so it is very important to find early MRI positive findings of knee instability.

Methods

We retrospectively collected the clinical and imaging data of 70 patients who underwent ACL reconstruction from January 2016 to December 2019; Based on clinical criteria, the patients were divided into a stable group (n = 57) and an unstable group (n = 13); We measured the MRI imaging evaluation indexes, including the position of the bone tunnel, graft status, and the anatomical factors; Statistical methods were used to compare the differences of imaging evaluation indexes between the two groups; The prediction equation was constructed and ROC curve was used to compare the prediction efficiency of independent prediction factors and prediction equation.

Results

There were significant differences in the abnormal position of tibial tunnel entrance, percentage of the position of tibial tunnel entrance, position of tibial tunnel exit, lateral tibial posterior slope (LTPS), width of intercondylar notch between stable knee joint group and unstable knee joint group after ACL reconstruction (P < 0.05); The position of tibial tunnel exits and the lateral tibial posterior slope (LTPS) and the sagittal obliquity of the graft were independent predictors among surgical factors and self-anatomical factors (P < 0.05); The prediction equation of postoperative knee stability was established: Logit(P) = -1.067–0.231*position of tibial tunnel exit + 0.509*lateral tibial posterior slope (LTPS)-2.105*sagittal obliquity of the graft; The prediction equation predicted that the AUC of knee instability was 0.915, the sensitivity was 84.6%, and the specificity was 91.2%.

Conclusions

We found that abnormalities of the position of the exit of the bone tunnel, lateral tibial posterior slope (LTPS) and sagittal obliquity of the graft were the early MRI positive findings of knee instability after ACL reconstruction. It is helpful for clinicians to predict the stability of knee joint after ACL reconstruction.

[Influence of lateral posterior tibial slope on tibial tunnel expansion after anatomical single-bundle anterior cruciate ligament reconstruction]

Objective

To investigate the influence of lateral posterior tibial slope (LPTS) on tibial tunnel expansion after anatomical single-bundle anterior cruciate ligament (ACL) reconstruction and the effect of tibial tunnel expansion on knee joint function.

Methods

A clinical data of 52 patients with ACL rupture, who underwent arthroscopic anatomical single-bundle reconstruction between November 2018 and December 2019, was retrospectively analyzed. There were 32 males and 20 females with an average age of 34.3 years (range, 14-64 years). There were 22 cases of left knee and 30 cases of right knee. The time from injury to operation ranged from 7 to 30 days, with an average of 15.9 days. The knee function was evaluated by International Knee Documentation Committee (IKDC) score and Lysholm score before operation and at 3 and 6 months after operation. At 3 and 6 months after operation, the LPTS and the width of exit, middle segment, entrance, and 2 cm from the exit of the articular surface of the tibial tunnel were measured based on MRI. The expansion of tibial tunnel was calculated and graded (degrees 0-3). According to LPTS, the patients were divided into group A (<6.0°), group B (6°-12°), and group C (>12°), and the difference in the expansion of tibial tunnel between groups was compared.

Results

All the 52 patients were followed up 6-12 months (mean, 7.1 months). The IKDC and Lysholm scores at 3 and 6 months after operation were significantly different from those before operation ( P<0.05); and the difference of knee scores between 3 and 6 months after operation was significant ( P<0.05). The tibial tunnel expanded after operation, and the relative expansion at the exit and the middle segment showed significant difference between 3 months and 6 months after operation ( P<0.05). The expansion degree of tibial tunnel was rated as degree 0 in 5 cases, degree 1 in 28 cases, degree 2 in 16 cases, and degree 3 in 3 cases at 3 months after operation, and degree 0 in 5 cases, degree 1 in 20 cases, degree 2 in 25 cases, and degree 3 in 2 cases at 6 months after operation. There was no significant difference in IKDC and Lysholm scores between patients with different expansion degrees of tibial tunnels ( P>0.05). The LPTS of 52 patients ranged from -0.8° to 18.7° (mean, 10.6°); there were 7 cases in group A, 24 cases in group B, and 21 cases in group C. There was no significant difference in age, gender, preoperative IKDC and Lysholm scores, and initial width of tibial tunnel between groups ( P>0.05). There was no significant difference in the relative expansion of tibial tunnel at exit and middle segment between groups at 3 months after operation ( P>0.05), and there was significant difference at 6 months after operation ( P<0.05).

Conclusion

After anatomical single-bundle reconstruction of ACL, the tibial tunnel would expand to some extent in a short time. LPTS had a significant effect on tibial tunnel expansion, and the larger the angle was, the more obvious the expansion of the proximal tibial tunnel was. However, early knee function is not affected by tibial tunnel expansion.

Mesenchymal stromal cells and platelet-rich plasma promote tendon allograft healing in ovine anterior cruciate ligament reconstruction

PURPOSE

The effect of bone marrow mesenchymal stromal cells (BMSCs) and platelet-rich plasma (PRP) on tendon allograft maturation in a large animal anterior cruciate ligament (ACL) reconstruction model was reported for the first time. It was hypothesised that compared with non-augmented ACL reconstruction, BMSCs and PRP would enhance graft maturation after 12 weeks and this would be detected using magnetic resonance imaging (MRI).

METHODS

Fifteen sheep underwent unilateral tendon allograft ACL reconstruction using aperture fixation and were randomised into three groups (n = 5). Group 1 received 10 million allogeneic BMSCs in 2 ml fibrin sealant; Group 2 received 12 ml PRP in a plasma clot injected into the graft and bone tunnels; and Group 3 (control) received no adjunctive treatment. At autopsy at 12 weeks, a graft maturation score was determined by the sum for graft integrity, synovial coverage and vascularisation, graft thickness and apparent tension, and synovial sealing at tunnel apertures. MRI analysis (n = 2 animals per group) of the signal-noise quotient (SNQ) and fibrous interzone (FIZ) was used to evaluate intra-articular graft maturation and tendon-bone healing, respectively. Spearman's rank correlation coefficient (r) of SNQ, autopsy graft maturation score and bone tunnel diameter were analysed.

RESULTS

The BMSC group (p = 0.01) and PRP group (p = 0.03) had a significantly higher graft maturation score compared with the control group. The BMSC group scored significantly higher for synovial sealing at tunnel apertures (p = 0.03) compared with the control group. The graft maturation score at autopsy significantly correlated with the SNQ (r = - 0.83, p < 0.01). The tunnel diameter of the femoral tunnel at the aperture (r = 0.883, p = 0.03) and mid-portion (r = 0.941, p = 0.02) positively correlated with the SNQ.

CONCLUSIONS

BMSCs and PRP significantly enhanced graft maturation, which indicates that orthobiologics can accelerate the biologic events in tendon allograft incorporation. Femoral tunnel expansion significantly correlated with inferior maturation of the intra-articular graft. The clinical relevance of this study is that BMSCs and PRP enhance allograft healing in a translational model, and biological modulation of graft healing can be evaluated non-invasively using MRI.

Biomedical nanomaterials: applications, toxicological concerns, and regulatory needs

Advances in cutting-edge technologies such as nano- and biotechnology have created an opportunity for re-engineering existing materials and generating new nano-scale products that can function beyond the limits of conventional ones. While the step change in the properties and functionalities of these new materials opens up new possibilities for a broad range of applications, it also calls for structural modifications to existing safety assessment processes that are primarily focused on bulk material properties. Decades after the need to modify existing risk management practices to include nano-specific behaviors and exposure pathways was recognized, relevant policies for evaluating, and controlling health risks of nano-enabled materials is still lacking. This review provides an overview of current progress in the field of nanobiotechnology rather than intentions and aspirations, summarizes long-recognized but still unresolved issues surrounding materials safety at the nanoscale, and discusses key barriers preventing generation and integration of reliable data in bio/nano-safety domain. Particular attention is given to nanostructured materials that are commonly used in biomedical applications.

A steep coronal graft bending angle is associated with bone tunnel enlargement of the posterolateral bundle after anterior cruciate ligament reconstruction

PURPOSE

The correlation between the graft bending angle (GBA) of the anteromedial bundle and posterolateral bundle after anterior cruciate ligament reconstruction (ACLR) and postoperative tunnel enlargement was evaluated.

METHODS

Two hundred fifty-eight patients (137 males, 121 females; mean age 27.3 years) who had undergone double-bundle ACLR were included. Computed tomographic scans of the operated knee were obtained at 2 weeks and 6 months postoperatively. The area of the tunnel aperture for femoral anteromedial tunnel (FAMT) and femoral posterolateral tunnel (FPLT) was measured; the area at 2 weeks after ACLR was subtracted from the area at 6 months after ACLR and then divided by the area at 2 weeks after ACLR. The femoral tunnel angles were obtained with Cobb angle measurements. The femoral tunnel angle in the coronal plane was measured relative to the tibial plateau (coronal GBA). On the median value, the patients were divided into two groups in each of FAMT and FPLT; those with a coronal GBA of FAMT of ≥27° were classified as group A, while those with a coronal GBA of <27° were classified as group B, those with a coronal GBA of FPLT of ≥23° were classified as group C, while those with a coronal GBA of<23° were classified as group D.

RESULTS

Group A included 129 knees, while group B included 129 knees. Groups A and B did not significantly differ regarding FAMT enlargement. Group C included 133 knees, while group D included 125 knees. The percentage of FPLT enlargement in group C was significantly smaller than that in group D (p = 0.001).

CONCLUSIONS

A steep coronal GBA of the FPLT after ACLR results in greater FPLT enlargement. The present findings suggest that surgeons should avoid creating a steep GBA of the FPLT in the outside-in technique.

Comparative Effectiveness and Safety of Allografts and Autografts in Posterior Cruciate Ligament Reconstruction Surgery: A Systematic Review

Purpose

To evaluate the evidence of the effectiveness and safety of allografts compared to autografts in posterior cruciate ligament reconstruction.

Methods

Four electronic databases were systematically searched for eligible randomized controlled studies. Crucial effectiveness outcomes included patient-reported function, activity level and symptoms, clinical knee stability, health-related quality of life, and patient satisfaction. Safety was evaluated through graft failures, revisions, reruptures and complications. The internal validity of the studies was assessed by the Cochrane risk of bias tool, and the strength of the evidence was judged according to the Grading of Recommendations, Assessment, Development and Evaluation (GRADE).

Results

Two randomized controlled studies were included: 50 patients were analyzed in the allograft group and 58 in the autograft group. No statistically significant postoperative differences were reported between the groups for patient-reported function, activity levels or symptoms. One study reported a statistically significant difference in instrumented postoperative anteroposterior knee laxity favoring stability in autografts. This difference is, however, not relevant in the clinical setting. Insufficient evidence was found to judge safety outcomes and because complications were poorly measured, and none of the studies reported on graft failure, revision or rerupture rates. The studies were judged with unclear to high risk of bias. The strength of the evidence for effectiveness and safety was judged to be low to very low, according to GRADE.

Conclusions

Allografts may be comparable to autografts for crucial effectiveness outcomes, but insufficient evidence was found to judge crucial safety outcomes due to poor reporting of safety measures and outcomes. Results should be interpreted with caution because there is lack of good-quality evidence to support the superiority of allografts over autografts due to the high risk of bias in the primary studies and overall very low strength of the body of evidence according to GRADE.

Level of Evidence

Systematic review of Level II studies.

Tibial tunnel enlargement after anatomic anterior cruciate ligament reconstruction with a bone-patellar tendon-bone graft. Part 2: Factors related to the tibial tunnel enlargement

BACKGROUND

Factors related to tunnel enlargement after anterior cruciate ligament (ACL) reconstruction should be evaluated by multivariate analysis, because the phenomenon has multifactorial characteristics. The purpose of this study was to elucidate the factors related to the tibial tunnel enlargement rate after anatomic ACL reconstruction with a bone-patellar tendon-bone (BTB) graft using multivariate analysis.

METHODS

Eighteen patients with unilateral ACL rupture were included. The anatomic rectangular-tunnel (ART) ACL reconstruction with a BTB autograft was performed. 3D CT models of the tibia, the tibial tunnel, and the bone plug at 3 weeks and 1 year after surgery were reconstructed and superimposed using a surface registration technique. The cross-sectional area (CSA) of the tibial tunnel perpendicular to the tunnel axis was evaluated at the aperture. The CSA was measured at 3 weeks and 1 year after surgery, and the tunnel enlargement rate at the aperture was calculated. Multiple linear regression analysis was performed to detect the significantly related factors to the tibial tunnel enlargement rate at the aperture among potential factors consisting of preoperative demographic factors and predisposing factors with the tibial tunnel.

RESULTS

The tibial tunnel enlargement rate at the aperture was 21.9 ± 14.1% (mean ± standard deviation). Multiple linear regression analysis detected the tendon length inside the tunnel as a significantly independent factor related to the tibial tunnel enlargement rate at the aperture (standardized β = 0.726, P = 0.008). There was no significant relationship between the tibial tunnel enlargement rate at the aperture and postoperative side-to-side difference (SSD) of the anterior knee laxity or Tegner activity level scale under single linear regression analysis.

CONCLUSION

The greater tendon length inside the tunnel was independently related to the higher tibial tunnel enlargement rate at the aperture 1-year after anatomic ACL reconstruction with a BTB graft under multiple linear regression analysis.

Morphological Changes of the Femoral Tunnel and Their Correlation With Hamstring Tendon Autograft Maturation up to 2 Years After Anterior Cruciate Ligament Reconstruction Using Femoral Cortical Suspension

BACKGROUND

Graft healing within the femoral tunnel after anterior cruciate ligament reconstruction (ACLR) using suspensory fixation could be reflected in graft maturation and tunnel morphological changes. However, the correlation between graft maturation and femoral tunnel changes remains unclear.

PURPOSE

To quantitatively evaluate femoral tunnel morphological changes and graft maturation and to analyze their correlation after ACLR using femoral cortical suspension.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients who underwent single-bundle ACLR with a hamstring tendon autograft using femoral cortical suspension were included. Preoperative and postoperative (at 6, 12, and 24 months) knee function were evaluated using KT-1000 arthrometer testing, the Lysholm knee scoring scale, and the International Knee Documentation Committee (IKDC) questionnaire. At 1 day, 6 months, 12 months, and 24 months after ACLR, 3-dimensional magnetic resonance imaging was performed to observe the morphology of the femoral tunnel and to evaluate graft maturation using the graft signal/noise quotient (SNQ). The Pearson product moment correlation coefficients (r) of femoral tunnel radii versus clinical outcomes and graft SNQs at last follow-up were analyzed.

RESULTS

A total of 22 patients completed full follow-up. KT-1000 arthrometer, Lysholm, and IKDC scores improved over time postoperatively, but no significant improvement was seen after 12 months (P < .05). The radius of the tunnel containing the graft and the SNQs of the femoral intraosseous graft and intra-articular graft were the highest at 6 months, and they decreased by 24 months but remained higher than their 1-day postoperative values (P < .05). Expansion mainly occurred at the anteroinferior wall of the femoral tunnel. The tunnel aperture radius was positively correlated with SNQs of the intraosseous graft (r = 0.591; P < .05) and intra-articular graft (r = 0.359; P < .05) but not with clinical outcomes.

CONCLUSION

After ACLR using suspensory fixation, morphological changes of the femoral tunnel were mainly observed in the part of the tunnel containing the graft, which expanded at 6 months and reduced by 24 months. Expansion mainly occurred at the anteroinferior wall of the femoral tunnel. Femoral tunnel expansion was correlated with inferior graft maturation but not with clinical outcomes.

Influence of three different fixation methods on femoral tunnel widening in ACL reconstructed patients evaluated using computed tomography (CT) scan

PURPOSE

To evaluate femoral tunnel widening in young and active patients undergoing ACL reconstruction with quadrupled hamstring graft with fixation on tibial side performed with a Bioscrew while femoral fixation performed with either a Tight rope Reverse Threaded (RT) or Transfix or another Bioscrew using CT scan.

MATERIAL AND METHOD

A total of 100 consecutive patients underwent single-bundle ACL reconstruction from January 2008 to March 2012. Eighty-six out of these were available with us till the final follow-up. Only 20-40-year-old males with unilateral ACL rupture less than a year old, diagnosed clinically and confirmed radiologically by magnetic resonance imaging, were selected for the study. All patients were evaluated clinically as well as radiologically at follow-up of 2 weeks, 1 month, 3 months, 6 months, 1 year and every 6 months thereafter. CT scans were performed at 2 weeks, 6 months, and 1 year postoperatively. The data acquired at the second week were considered as baseline data and were used for comparison with the data acquired at 6 months and 1 year.

RESULTS

The dilatation at the aperture was significantly more in the Tight rope RT group as compared to the other two groups (p value 0.019 and 0.021 for sagittal and coronal images, respectively).

CONCLUSION

There is no significant difference between the three different fixation modes in context of tunnel enlargement except with Tight rope RT device which leads to statistically significant dilatation at aperture. Future studies with longer follow-up are required to evaluate its clinical implications.

In vivo assessment of high-molecular-weight polyethylene core suture tape for intra-articular ligament reconstruction: an animal study

AIMS

Options for the treatment of intra-articular ligament injuries are limited, and insufficient ligament reconstruction can cause painful joint instability, loss of function, and progressive development of degenerative arthritis. This study aimed to assess the capability of a biologically enhanced matrix material for ligament reconstruction to withstand tensile forces within the joint and enhance ligament regeneration needed to regain joint function.

MATERIALS AND METHODS

A total of 18 New Zealand rabbits underwent bilateral anterior cruciate ligament reconstruction by autograft, FiberTape, or FiberTape-augmented autograft. Primary outcomes were biomechanical assessment (n = 17), microCT (µCT) assessment (n = 12), histological evaluation (n = 12), and quantitative polymerase chain reaction (qPCR) analysis (n = 6).

RESULTS

At eight weeks, FiberTape alone or FiberTape-augmented autograft demonstrated increased biomechanical stability compared with autograft regarding ultimate load to failure (p = 0.035), elongation (p = 0.006), and energy absorption (p = 0.022). FiberTape-grafted samples also demonstrated increased bone mineral density in the bone tunnel (p = 0.039). Histological evaluation showed integration of all grafts in the bone tunnels by new bone formation, and limited signs of inflammation overall. A lack of prolonged inflammation in all samples was confirmed by quantification of inflammation biomarkers. However, no regeneration of ligament-like tissue was observed along the suture tape materials. Except for one autograft failure, no adverse events were detected.

CONCLUSION

Our results indicate that FiberTape increases the biomechanical performance of intra-articular ligament reconstructions in a verified rabbit model at eight weeks. Within this period, FiberTape did not adversely affect bone tunnel healing or invoke a prolonged elevation in inflammation. Cite this article: Bone Joint J 2019;101-B:1238-1247.

Tibial tunnel enlargement after anatomic anterior cruciate ligament reconstruction with a bone-patellar tendon-bone graft. Part 1: Morphological change in the tibial tunnel

BACKGROUND

Three-dimensional (3D) computed tomography (CT) is reliable and accurate imaging modality for evaluating tunnel enlargement after anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to evaluate the tibial tunnel enlargement including the morphological change after anatomic ACL reconstruction with a bone-patellar tendon-bone (BTB) graft using 3D CT models.

METHODS

Eighteen patients with unilateral ACL rupture were included. The anatomic rectangular-tunnel (ART) ACL reconstruction with a BTB autograft was performed. 3D CT models of the tibia, the tibial tunnel, and the bone plug at 3 weeks and 1 year after surgery were reconstructed and superimposed using a surface registration technique. The cross-sectional area (CSA) of the tibial tunnel perpendicular to the tunnel axis was evaluated at the aperture and 5, 10, and 15-mm distal from the aperture. The CSA was measured at 3 weeks and 1 year after surgery and compared between the two time points. The locations of the center and the anterior, posterior, medial, and lateral edges of the tunnel footprint were also evaluated based on the coordinate system for the tibial plateau and compared between the two time points.

RESULTS

At the aperture, the CSA of the tibial tunnel at 1 year after surgery was significantly larger by 21.9% than that at 3 weeks (P < 0.001). In contrast, the CSA at 1 year was significantly smaller than that at 3 weeks at 10 and 15-mm distal from the aperture (P = 0.041 and < 0.001, respectively). The center of the tunnel footprint significantly shifted postero-laterally with significant posterior shift of the anterior/posterior edges and lateral shift of the lateral edge (P < 0.001).

CONCLUSION

The tibial tunnel enlarged at the aperture by 22% 1-year after anatomic ACL reconstruction with a BTB graft, and the tunnel morphology changed in a postero-lateral direction at the aperture and into conical shape inside the tunnel.

Anterior cruciate ligament reconstruction is associated with greater tibial tunnel widening when using a bioabsorbable screw compared to an all-inside technique with suspensory fixation

PURPOSE

To compare clinical outcomes and tunnel widening following anterior cruciate ligament reconstruction (ACLR) performed with an all-inside technique (Group A) or with a bioabsorbable tibial screw and suspensory femoral fixation (Group B).

METHODS

Tunnel widening was assessed using computed tomography (CT) and a previously validated analytical best fit cylinder technique at approximately 1-year following ACLR. Clinical follow-up comprised evaluation with IKDC, KSS, Tegner, Lysholm scores, and knee laxity assessment.

RESULTS

The study population comprised 22 patients in each group with a median clinical follow-up of 24 months (range 21-27 months). The median duration between ACLR and CT was 13 months (range 12-14 months). There were no significant differences in clinical outcome measures between groups. There were no differences between groups with respect to femoral tunnel widening. However, there was a significantly larger increase in tibial tunnel widening, at the middle portion, in Group B (2.4 ± 1.5 mm) compared to Group A (0.8 ± 0.4 mm) (p = 0.027), and also at the articular portion in Group B (1.5 ± 0.8 mm) compared to Group A (0.8 ± 0.8 mm) (p = 0.027).

CONCLUSION

Tibial tunnel widening after ACLR using hamstring tendon autograft is significantly greater with suspensory femoral fixation and a bioabsorbable tibial interference screw when compared to an all-inside technique at a median follow-up of 2 years. The clinical relevance of this work lies in the rebuttal of concerns arising from biomechanical studies regarding the possibility of increased tunnel widening with an all-inside technique.

LEVEL OF EVIDENCE

III.

Does Second-Generation Suspensory Implant Negate Tunnel Widening of First-Generation Implant Following Anterior Cruciate Ligament Reconstruction?

Purpose

Tunnel widening following anterior cruciate ligament (ACL) reconstruction is commonly observed. Graft micromotion is an important contributing factor. Unlike fixed-loop devices that require a turning space, adjustable-loop devices fit the graft snugly in the tunnel. The purpose of this study is to compare tunnel widening between these devices. Our hypothesis is that the adjustable-loop device will create lesser tunnel widening.

Materials and Methods

Ninety-eight patients underwent ACL reconstruction from January 2013 to December 2014. An adjustable-loop device was used in 54 patients (group 1) and a fixed-loop device was used in 44 patients (group 2). Maximum tunnel widening at 1 year was measured by the L’Insalata’s method. Functional outcome was measured at 2-year follow-up.

Results

The mean widening was 4.37 mm (standard deviation [SD], 2.01) in group 1 and 4.09 mm (SD, 1.98) in group 2 (p=0.511). The average International Knee Documentation Committee score was 78.40 (SD, 9.99) in group 1 and 77.11 (SD, 12.31) in group 2 (p=0.563). The average Tegner-Lysholm score was 87.25 (SD, 3.97) in group 1 and 87.29 in group 2 (SD, 4.36) (p=0.987). There was no significant difference in tunnel widening and functional outcome between the groups.

Conclusions

The adjustable-loop device did not decrease the amount of tunnel widening when compared to the fixed-loop device. There was no significant difference in outcome between the two fixation devices.

Level of Evidence

Level 3, Retrospective Cohort

Long-term follow-up after anterior cruciate ligament reconstruction using a press-fit quadriceps tendon-patellar bone autograft

Background

The use of a quadriceps tendon-patellar bone (QTPB) autograft provides an alternative procedure in primary reconstruction of the anterior cruciate ligament (ACL). Using the press-fit technique for femoral fixation and knotting over a bone bridge as well as additional spongiosa filling for tibial fixation can completely eliminate the need for fixation implants. The objective of this study was to evaluate the long-term clinical, functional and radiological results of this operating method.

Methods

Sixty-nine patients (27 female-42 male) were included in this study. Fifty-seven patients (83%) received a comprehensive follow-up review after an average period of 7.5 years (range: 7–8.7). All other patients were surveyed by telephone. Six patients (9%) suffered a re-rupture of the ACL graft caused by a new related trauma and were therefore excluded from the statistical analysis.

Results

Of all patients, 98% were satisfied with the operation. Normal or almost normal results were recorded in the subjective IKDC scores form by 88% of the patients. The Lysholm score demonstrated very good and good results in 83% of the patients. Only 1 patient reported minor complaints in the donor area. Seven (12%) patients developed Cyclops syndrome with limited knee extension. This complication was treated arthroscopically within the first year postoperatively. Their results on follow-up were not worse than the results of the patients without Cyclops syndrome.

Regarding the 57 patients who received a comprehensive evaluation, the stability test with the KT-1000 Arthrometer yielded a difference of less than 3 mm in the contralateral comparison for 89% of the operated knees. The pivot-shift test was normal in 79% and almost normal in 21%. In the Single-leg Triple Hop Test, patients achieved an average of 98% of the hopping distance attained with the contralateral leg. The radiological examination revealed a slight deterioration in the Kellgren-Lawrence Score in 2 patients.

Conclusion

The ACL reconstruction using the QTPB autograft performed with the press-fit technique leads to good results in comparison with published results of established procedures for primary ACL surgery using other autografts. Further investigations should involve comparative studies with the objective of providing evidence-based, individually adapted therapy for ACL rupture.

Electronic supplementary material

The online version of this article (10.1186/s12891-018-2271-8) contains supplementary material, which is available to authorized users.

Incorporating BMP-2 and skeletal muscle to a semitendinosus autograft in an oversized tunnel yields robust bone tunnel ossification in rabbits: Toward single-step revision of failed anterior cruciate ligament reconstruction

BACKGROUND

Bone tunnel widening after anterior cruciate ligament (ACL) reconstruction is a known complication that can lead to graft failure. Subsequent revision surgery typically involves a two-stage procedure. The aim of this study was to test a novel autologous tendon graft retaining muscle tissue combined with Human Recombinant Bone Morphogenetic Protein-2 (rh-BMP-2) leading to rapid ossification of the muscle tissue, simultaneously replenishing bone stock and producing a mechanically stable bone-tendon insertion.

METHODS

In 12 skeletally mature New Zealand rabbits, the ACL was resected and oversized bone tunnels were drilled to model tunnel widening. The ipsilateral semitendinosus muscle-tendon graft was harvested and folded twice. Muscle tissue was removed in the middle third but retained at both distal ends. One side was wrapped in a collagen sponge loaded with rh-BMP-2 while the other end was used as its own control.

RESULTS

All animals were euthanized after six weeks. Micro-computed tomography (micro-CT) was used to analyze bone formation in 12 animals, with additional biomechanical testing to failure and histology performed for six animals each. Micro-CT showed that bone densities were higher by a factor of 2.4 in treated graft ends compared with their controls. Biomechanical testing showed a mean overall failure load of 37.5 N. Histology showed that the trabecular bone surrounding the implant was significantly (P = 0.0087) thicker on the treated (85.5 μm) compared with the control side (68.2 μm).

CONCLUSIONS

We conclude that a semitendinosus graft retaining the muscle tissue stimulated by recombinant Bone Morphogenetic Protein-2 (BMP-2) allows robust osseointegration of the graft within an oversized bone tunnel in an animal model.

Graft Considerations in Posterior Cruciate Ligament Reconstruction

PURPOSE OF REVIEW

To highlight current and established concepts regarding PCL injury and reconstruction.

RECENT FINDINGS

Recent biomechanical and clinical studies have brought attention to improved surgical techniques and clinical outcomes of PCL reconstruction. In contrast to anterior cruciate ligament (ACL) injuries, isolated posterior cruciate ligament (PCL) injuries occur much less frequently and have traditionally been treated non-operatively. Even when a PCL injury meets operative indications, outcomes of PCL reconstruction historically do not match the success rates of ACL reconstruction procedures. As such, there remains controversy regarding appropriate indications and techniques for surgical repair leading to a paucity of conclusive data regarding surgical outcomes. Recently, however, there has been an increase in focus on the role of the PCL in proper knee biomechanics and negative long-term sequelae of chronic PCL insufficiency. This improved understanding has led to advancements in surgical technique and graft options for PCL reconstruction.

A prospective study of coracoclavicular ligament reconstruction with autogenous peroneus longus tendon for acromioclavicular joint dislocations

BACKGROUND

Anatomic coracoclavicular (CC) ligament reconstruction (ACCR) provides good outcomes for Rockwood type III and VI acromioclavicular (AC) joint dislocations. Various grafts have been used, but complications from graft harvesting are not uncommon. This study examined the clinical and radiographic outcomes of patients with AC joint dislocations repaired with the autogenous anterior half of the peroneus longus tendon (AHPLT) to achieve ACCR.

METHODS

Patients with a Rockwood type III to V AC joint dislocation and magnetic resonance imaging of the disruption of the CC ligaments, as well as the AC capsule, were prospectively recruited. Patients received ACCR using an autogenous AHPLT graft and were evaluated clinically and radiographically preoperatively and at 1, 3, 6, and 12 months postoperatively.

RESULTS

A total of 18 patients (mean age, 51 years) were prospectively recruited and received an autogenous AHPLT graft ACCR. Fifteen patients completed clinical and radiographic follow-up examinations at 12 months. The mean Constant score (CS) was 51 preoperatively and 93 at 12 months (P <.005). No significant difference was noted at 12 months between the CS of the injured and contralateral shoulder. The mean American Orthopedic Foot and Ankle Society score at 12 months was 99, and this was not different from the value at any other time point. Loss of reduction occurred in 10 patients (56%), and tunnel widening was observed in 9 (50%), but neither was significantly correlated with functional outcome.

CONCLUSION

Autogenous AHPLT appears to be a reliable tendon graft source for CC ligament reconstruction.

The effect of humeral tunnel locations on radiographic tunnel changes in baseball players following medial ulnar collateral ligament reconstruction: comparison of anatomic and nonanatomic locations

BACKGROUND

There has been no study on radiologic changes after medial ulnar collateral ligament (MUCL) reconstruction and related clinical features.

METHODS

Data from 39 baseball players who underwent MUCL reconstruction were collected and analyzed. The baseball players were classified into 2 groups according to the starting point of the humeral tunnel: (1) the lower tip of the medial epicondyle (group NA, n = 21) and (2) the remnant of the MUCL (group A, n = 18). Bone tunnel characteristics and changes were evaluated by computed tomography (CT) at 3 and 9 months postoperatively. Outcome measures consisted of the visual analog scale, range of motion (ROM), the Conway scale, and the presence of ulnar nerve irritation postoperatively.

RESULTS

The mean diameter of the humeral entry was 4.0 mm (range, 3.4-5.1 mm) on the first CT scan, which increased to 5.5 mm (range, 3.2-7.2 mm) on the follow-up CT scan (P < .001). The mean diameter of the ulnar tunnel was 2.8 mm (range, 1.1-3.3 mm) on the first CT scan, which decreased to 1.6 mm (range, 0-4.3 mm) on the follow-up CT scan (P < .001). The between-group comparison revealed no differences in the changes in the diameter of the humeral and ulnar tunnels. A statistically significant correlation was not found between athletic performance measured by the Conway scale and the radiologic changes on CT evaluation (P = .182). Group A showed improvement in extension from 7° preoperatively to 1° postoperatively (P < .001) and in flexion from 126° preoperatively to 136° postoperatively (P < .001), while group NA did not achieve statistical significance in ROM improvement after the operation.

CONCLUSIONS

Humeral tunnel widening was commonly observed, while the ulnar tunnel was maintained or became narrowed conversely. The humeral tunnel placements did not affect tunnel changes after the surgical procedure; however, MUCL reconstruction with the anatomic location of the humeral tunnel yielded substantial improvement in elbow ROM.

Tibial Plateau Fracture Following Anterior Cruciate Ligament Reconstruction with a Bone-Patellar Tendon-Bone Allograft: A Case Report

CASE

A 36-year-old woman sustained a medial tibial plateau fracture involving a tibial tunnel that had been used 4 years prior for an anterior cruciate ligament (ACL) reconstruction with a bone-patellar tendon-bone (BPTB) allograft in the same knee. At 26 months following open reduction and internal fixation of the tibial plateau fracture (6 years following the index ACL reconstruction), the patient returned to full activity.

CONCLUSION

To our knowledge, this is the first report of a tibial plateau fracture following ACL reconstruction with a BPTB allograft, which adds to the paucity of literature discussing tibial plateau fractures following ACL reconstruction and discusses the potential predisposing factors to fracture such as ACL graft selection and surgical technique.

Stress distribution is deviated around the aperture of the femoral tunnel in the anatomic anterior cruciate ligament reconstruction

PURPOSE

Final tunnel location in the anterior cruciate ligament (ACL) reconstruction is unpredictable due to tunnel widening and/or transposition. The mechanical stress around the tunnel aperture seems to be a major factor but is not fully investigated. The purpose of this study was to measure the stress from the ACL graft around the tunnel aperture when the ACL graft tension reaches its peak.

METHODS

Six cadaveric knees were used. Single-bundle ACL reconstruction was performed using a hamstrings graft. Both femoral and tibial tunnels were created at the centre of the original ACL footprint. A 7-mm-internal-diameter aluminium cylinder with pressure sensors was placed in the femoral tunnel. Hamstrings graft with a microtension sensor was inserted. After fixation, passive extension-flexion was performed while monitoring the tunnel aperture pressure and the graft tension simultaneously. The pressure on the femoral tunnel aperture when the ACL graft tension reach its peak was compared between four directions.

RESULTS

The ACL graft tension peaked (67 ± 49 N) at full extension (-5.8 ± 4.1°). Pressure at the femoral tunnel aperture was different between different directions (p < 0.01). Distal part had significantly larger pressure (1.7 ± 1.3 MPa) than the other directions (p < 0.01). Second largest pressure was carried in the anterior part (0.6 ± 0.5 MPa), followed by proximal and posterior parts (0.4 ± 0.3, 0.2 ± 0.2 MPa respectively).

CONCLUSION

The stress distribution at the femoral tunnel aperture is not equal in different directions, while the distal part dominantly bears the stress from the ACL graft. Surgeons should pay close attention to the distal edge of the femoral tunnel which should be inside the anatomic ACL footprint eventually.

Patient age as a preoperative factor associated with tunnel enlargement following double-bundle anterior cruciate ligament reconstruction using hamstring tendon autografts

PURPOSE

A few studies have detected associations of post-operative tunnel enlargement with sex, age, and the timing of anterior cruciate ligament reconstruction (ACLR). The aim of the present study was to investigate the correlation between post-operative tunnel enlargement following ACLR using hamstring tendon autografts and preoperative factors. The authors hypothesized that tunnel enlargement is associated with age in patients undergoing ACLR.

METHODS

One hundred and six patients (male, n = 57; female, n = 49; mean age, 26.9 years) who underwent double-bundle ACL reconstruction were included in the present study. The time between injury and surgery was 26.3 ± 71.4 weeks. Computed tomographic scans of the operated knee were obtained at 2 weeks and 6 months after surgery. The area of the tunnel aperture was measured for the femoral anteromedial tunnel (FAMT), femoral posterolateral tunnel (FPLT), tibial anteromedial tunnel (TAMT), and tibial posterolateral tunnel. The percentage of tunnel area enlargement was defined as the area at 2 weeks after ACLR subtracted from the area at 6 months after ACLR and then divided by the area at 2 weeks after ACLR. Spearman's correlation coefficient was calculated for each factor. The patients were divided into two groups based on age. Patients aged <40 and ≥40 years were assigned to Groups A and B, respectively. The differences in the outcomes and characteristics of the two groups were evaluated.

RESULTS

The percentage of enlargement of the FAMT, FPLT, and TAMT was correlated with patient age (r = 0.31, p = 0.001; r = 0.24, p = 0.012; and r = 0.30, p = 0.002, respectively). In total, 87 and 19 knees were classified into Groups A and B, respectively, based on patient age. The percentage of enlargement of the FAMT was significantly higher in Group B than A (78 vs. 60%, respectively; p = 0.01). The percentage of enlargement of the TAMT was significantly higher in Group B than A (53 vs. 36%, respectively; p = 0.03).

CONCLUSION

The percentage of enlargement of the FAMT and TAMT was associated with patient age. These findings suggest the need to consider the possibility of tunnel enlargement when double-bundle ACLR is performed for patients aged >40 years. Age was a preoperative factor associated with tunnel enlargement.

LEVEL OF EVIDENCE

III.

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

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

Single-bundle versus double-bundle autologous anterior cruciate ligament reconstruction: a meta-analysis of randomized controlled trials at 5-year minimum follow-up

BACKGROUND

Both single-bundle (SB) and double-bundle (DB) techniques were widely used in anterior cruciate ligament (ACL) reconstruction recently. Nevertheless, up to now, no consensus has been reached on whether the DB technique was superior to the SB technique. Moreover, follow-up of the included studies in the published meta-analyses is mostly short term. Our study aims to compare the mid- to long-term outcome of SB and DB ACL reconstruction concerning knee stability, clinical function, graft failure rate, and osteoarthritis (OA) changes.

METHODS

This study followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The PubMed, Embase, and the Cochrane Library were searched from inception to October 2017. The study included only a randomized controlled trial (RCT) that compared SB and DB ACL reconstruction and that had a minimum of 5-year follow-up. The Cochrane Collaboration's risk of bias tool was used to assess the risk of bias for all included studies. Stata/SE 12.0 was used to perform a meta-analysis of the clinical outcome.

RESULTS

Five RCTs were included, with a total of 294 patients: 150 patients and 144 patients in the DB group and the SB group, respectively. Assessing knee stability, there was no statistical difference in side-to-side difference and negative rate of the pivot-shift test. Considering functional outcome, no significant difference was found in proportion with International Knee Documentation Committee (IKDC) grade A, IKDC score, Lysholm scores, and Tegner scores. As for graft failure rate and OA changes, no significant difference was found between the DB group and the SB group.

CONCLUSION

The DB technique was not superior to the SB technique in autologous ACL reconstruction regarding knee stability, clinical function, graft failure rate, and OA changes with a mid- to long-term follow-up.

The remnant preservation technique reduces the amount of bone tunnel enlargement following anterior cruciate ligament reconstruction

PURPOSE

The aim of the present study was to investigate the correlation between postoperative tunnel enlargement after ACLR and remnant tissue preservation using the hamstring tendon.

METHODS

One hundred and ninety-two subjects (male, n = 101; female, n = 91; mean age 27.1) who had undergone double-bundle ACL reconstruction were included in the present study. The patients were divided into two groups: the remnant tissue preservation group (Group R) and the non-remnant tissue preservation group (Group N). Computed tomographic scans of the operated knee were obtained at 2 weeks and 6 months after surgery. The area of the tunnel aperture for the anteromedial femoral tunnel (FAMT), posterolateral femoral tunnel (FPLT), anteromedial tibial tunnel (TAMT), and posterolateral tibial tunnel (TPLT) was measured. The area at 2 weeks after ACLR was subtracted from the area at 6 months after ACLR and then divided by the area at 2 weeks after ACLR. The differences in the outcomes and characteristics of the two groups were evaluated.

RESULTS

Seventy-seven knees were classified into Group R, and 115 knees were classified into Group N. The age, gender, and body mass index did not differ to a statistically significant extent. The percentages of FAMT and TAMT enlargement in Group R were significantly smaller in comparison with Group N (P = 0.003 and P = 0.03, respectively). The percentage of FPLT and TPLT enlargement in the two groups did not differ to a statistically significant extent.

CONCLUSION

The remnant-preserving technique reduces the amount of bone tunnel enlargement. The present findings indicate the advantages of the remnant-preserving ACLR technique, and therefore the remnant-preserving technique should be recommended.

LEVEL OF EVIDENCE

II.

Tunnel widening after single- versus double-bundle anterior cruciate ligament reconstruction: a randomized 8-year follow-up study

OBJECTIVE

The purpose of this study was to compare the single-bundle (SB) and double-bundle (DB) surgical techniques for anterior cruciate ligament (ACL) reconstruction with regard to tunnel widening, isokinetic muscle strength, and clinical outcomes over an 8-year follow-up period.

METHODS

This study included 31 patients with ACL injury who underwent ACL reconstruction via the SB (n = 16) or the DB (n = 15) technique. Isokinetic and concentric strength measurements of the quadriceps and hamstring muscles were conducted at postoperative 6 months and postoperative 8 years, and 3D-CT scans of the knee joints were performed on the 2nd, 3rd and 6th month, and the 8th year postoperatively. Clinical evaluations were performed at 8 years postoperatively with the International Knee Documentation Committee (IKDC), Tegner, and Lysholm knee scoring systems.

RESULTS

There was marked widening of the parts of the femoral tunnel close to the knee joint in both the SD and the DB groups. There was no difference between the two groups in terms of clinical results and isometric muscle strength at postoperative 8 years; however, there was a significant difference between the preoperative and 6 months postoperative clinical and strength results in both group (P < 0.05). There was no difference between the groups in IKDC score, Lysholm score, Tegner activity scale, and anterior drawer test at postoperative 8 years. On evaluation of the anteromedial bundles alone, the DB group had greater widening than the SB group.

CONCLUSION

In this study, we have found that the tunnels continue to enlarge after 6 months. However, that has no impact in patients comfort and that did not made any change in our daily routine. On the other hand, we found that the reconstruction of the double-band ligament technique is useless for non-professional athletes.

Tunnel widening after ACL reconstruction with aperture screw fixation or all-inside reconstruction with suspensory cortical button fixation: Volumetric measurements on CT and MRI scans

BACKGROUND

Tunnel widening after anterior cruciate ligament reconstruction (ACLR) is influenced by the surgical and fixation techniques used. Computed tomography (CT) is the most accurate image modality for assessing tunnel widening, but magnetic resonance imaging (MRI) might also be reliable for tunnel volume measurements. In the present study tunnel widening after ACLR using biodegradable interference screw fixation was compared with all-inside ACLR using button fixation, with tunnel volume changes being measured on CT and MRI scans.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

Thirty-three patients were randomly assigned to hamstring ACLR using a biodegradable interference screw or all-inside cortical button fixation. CT and MRI scanning were done at the time of surgery and six months after. Tunnel volume changes were calculated and compared.

RESULTS

On CT, femoral tunnel volumes changed from the postoperative state (100%) to 119.8% with screw fixation and 143.2% with button fixation (P=0.023). The changes in tibial tunnel volumes were not significant (113.9% vs. 117.7%). The changes in bone tunnel volume measured on MRI were comparable with those on CT only for tunnels with interference screws. Tibial tunnels with button fixation were significantly underestimated on MRI scanning (P=0.018).

CONCLUSIONS

All-inside ACLR using cortical button fixation results in increased femoral tunnel widening in comparison with ACLR with biodegradable interference screw fixation. MRI represents a reliable imaging modality for future studies investigating tunnel widening with interference screw fixation.

How to evaluate bone tunnel widening after ACL reconstruction - a critical review

Background

Comparing different imaging modalities and methods for assessment tunnel widening after ACL reconstruction and providing a detailed evidence-based literature overview.

Methods

PubMed was searched from 1970 to 2016 using the terms "ACL reconstruction" and "tunnel" and "imaging" or "CT" or "computerized tomography" or "MRI" or "magnetic resonance imaging" or "radiographs". 647 studies were found. 575 articles were excluded due to absence of specific radiological measurement methods of tunnel widening and 40 due to repetition of a previously published radiological measurement method. 32 articles were included reporting interand intraobserver reliabilities of tunnel measurement methods after ACL reconstruction.

Results

A variety of different algorithms and measurement methods using radiographs, magnetic resonance imaging, computed tomography or SPECT/CT evaluating tunnel position and bone tunnel enlargement have been described. Tunnel delination restricts an exact analysis using X-ray. Measurements using CT or MR were mostly obtained perpendicular to the tunnel axis or using specialized software for tunnel volume calculation in 3D.Based on the review the width of the femoral and tibial tunnels should be assessed perpendicular to the tunnel axis at different levels in relation to the joint. At least one measurement should be performed at the tunnel entrance, exit and midpoint of the tunnel.

Conclusion

CT should be considered the gold standard assessing tunnel widening in patients after ACL reconstruction. If specialized software is available calculating the tunnel volume, measurements should be preferably performed in 3D CT.

Level of evidence

II.

Bone Tunnel Enlargement after ACL Reconstruction with Hamstring Autograft Is Dependent on Original Bone Tunnel Diameter

Background  Bone tunnel enlargement is a well-established phenomenon following anterior cruciate ligament (ACL) reconstruction, and is related to soft tissue grafts, suspension fixation devices, and absorbable implants. Severe tunnel enlargement can lead to reconstruction failure. The correlation between bone tunnel enlargement following ACL reconstruction and original bone tunnel diameter has not been elucidated.

Purpose  To determine whether bone tunnel enlargement after ACL reconstruction with hamstring autograft is dependent on original tunnel diameter established during primary ACL reconstruction.

Materials and Methods  A retrospective review was conducted on 56 patients scheduled for ACL revision surgery who had undergone computed tomography (CT) scanning as part of their preoperative evaluation. All patients had undergone previous hamstring ACL reconstruction. Original femoral and tibial bone tunnel diameters were extracted from operative reports, and femoral and tibial bone tunnel enlargement was assessed on CT serial sections. The correlation between original tunnel diameter and bone tunnel enlargement was investigated using regression analysis.

Results  Mean tibial bone tunnel enlargement was significantly and inversely dependent on the original tibial bone tunnel diameter with a correlation coefficient of −0.55 per unit (7 mm = +1.93 mm, 8 mm = +1.43 mm, 9 mm = 0.83 mm, p  = 0.007). Thus, every additional increase (mm) in diameter of the original tibial bone tunnel reduces the extend of tunnel widening by 0.55 mm.

Conclusions  The results of this study indicate that tibial bone tunnel enlargement following ACL reconstruction is dependent on original tibial bone tunnel diameter with smaller diameter tunnels developing more tunnel enlargement than larger tunnels. The contributing factors remain unclear and need to be further investigated.

3D Computed Tomography Evaluation of Morphological Changes in the Femoral Tunnel After Medial Patellofemoral Ligament Reconstruction With Hamstring Tendon Graft for Recurrent Patellar Dislocation

BACKGROUND

Reconstruction of the medial patellofemoral ligament (MPFL) for recurrent lateral patellar dislocation is gaining popularity. However, the morphological changes in the femoral tunnel after MPFL reconstruction are still not fully documented.

PURPOSE

This study used 3-dimensional (3D) computed tomography to evaluate morphological changes in the femoral tunnel after MPFL reconstruction with hamstring tendon graft to investigate factors affecting the phenomenon and to elucidate whether it is associated with clinical outcomes.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twenty-three patients with recurrent patellar dislocation were prospectively enrolled in this study. The patients included 6 males and 17 females with a mean age of 24 years (range, 14-53). The MPFL was reconstructed by creating 2 patellar bone sockets and 1 femoral bone socket anatomically under X-ray control, and the semitendinosus autograft was fixed with cortical suspension devices. Computed tomography scans obtained 3 weeks and 1 year after surgery were reconstructed into 3D constructs with a volume analyzer. Cross-sectional areas (CSAs) of the aperture and inside the femoral tunnel were compared between the 2 time points. Likewise, the location of tunnel walls and center of the femoral tunnel footprint were evaluated. Relationships were assessed between femoral tunnel morphological changes and potential risk factors-such as age, body mass index, sex, femoral tunnel positioning, patellar height, sulcus angle, congruence angle, lateral tilt angle, degree of trochlear dysplasia, lateral deviation of the tibial tubercle, and Kujala score.

RESULTS

No patient reported recurrence of patellar dislocation during the follow-up period. The CSA of the femoral tunnel aperture enlarged by 41.1% ± 34.7% ( P < .01). The center, anterior border, and proximal border of the femoral tunnel significantly shifted in the anterior direction ( P < .01). The distal border significantly shifted in both anterior and distal directions ( P < .01). Patella alta was associated with distal migration of the tunnel center ( P < .05). Morphological changes were not associated with other risk factors or Kujala score.

CONCLUSION

The CSA of the femoral tunnel aperture enlarged, and the tunnel aperture migrated anteriorly with time after MPFL reconstruction. Risk factors for patellar dislocation other than patella alta did not influence morphological changes of the femoral tunnel.

Fibrin clot prevents bone tunnel enlargement after ACL reconstruction with allograft

PURPOSE

Bone tunnel enlargement is a feared complication after ACL reconstruction. The aim of this study was to evaluate whether adding a fibrin clot to the allograft for anatomic single-bundle ACL reconstruction would reduce tunnel widening.

METHODS

Fifty patients who underwent anatomic single-bundle ACL reconstruction were included. Twenty-five patients received an allograft alone, and 25 patients received an allograft with fibrin clot. All patients underwent standard plain anteroposterior and lateral radiographs of the operated knee immediately after surgery and at 1-year follow-up. The size of the tunnels was measured at both time points to calculate tunnel widening. Tunnel widening at 1 year was compared between the allograft and the allograft + fibrin clot group.

RESULTS

There was significantly less tunnel widening in the allograft + fibrin clot group for the femoral tunnel width in the middle and distal portion of the tunnel and for the tibial tunnel width in the proximal and distal portions, as compared to the allograft only group.

CONCLUSION

Adding a fibrin clot to the allograft in anatomic single-bundle ACL reconstruction reduces the amount of tunnel widening at 1-year follow-up. Reducing tunnel widening may positively affect outcomes after ACL surgery and may prevent inadequate bone stock during ACL revision procedures.

LEVEL OF EVIDENCE

Case-control study, Level III.