Bone Tunnel Diameter Research Articles

Comparison of tunnel widening between interference screw and suture disc fixation after ACL reconstruction using CT scan

<p class="abstract"><strong>Background:</strong> <span lang="EN-IN">It is important to study the cause of tunnel widening which occurs after anterior cruciate ligament (ACL) reconstruction as it may affect tendon to bone healing. Amount of tunnel enlargement that happens after different fixation methods like interference screw or suture discs needs to be compared.</span>The objective of the study was <span lang="EN-IN">to test the hypothesis that aperture fixation (interference screw) reduces tunnel enlargement compared to suspensory fixation (suture disc) due to reduced graft tunnel motion.</span></p><p class="abstract"><strong>Methods:</strong> <span lang="EN-IN">24 bone tunnel diameters in 12 patients were evaluated by CT scan postoperatively after ACL reconstruction to measure tunnel widening. Two groups were formed, one consisting of 14 tunnels fixed by interference screws (IFS) and other consisting of 10 tunnels fixed with suture disc (SD). The difference between the two groups was compared by unpaired student’s t test</span>.<strong></strong></p><p class="abstract"><strong>Results:</strong> <span lang="EN-IN">The mean tunnel widening in IFS group was 0.414mm while that in the SD group was 1.23mm. The difference between the means of the two groups was statistically significant (p<0.001). </span></p><p class="abstract"><strong>Conclusions:</strong> <span lang="EN-IN">Tunnel widening phenomenon was significantly less with anatomic IFS fixation as compared to suture disc fixation probably due to reduced motion of graft within the walls of bony tunnel and consequently better graft healing.</span></p>

Bone tunnel widening following arthroscopic reconstruction of anterior cruciate ligament (Acl) using hamstring tendon autograft and its functional consequences

Background: To evaluate the correlation between bone tunnel diameter following Anterior cruciate ligament (ACL) reconstruction measured by computed tomography (CT) using multiplanar reconstruction (MPR) and functional outcome. Materials and methods: This study is a prospective study. Fifteen patients (14 men and 1 women, with mean age 30.27 years) who had undergone ACL reconstruction with hamstring tendon auto graft had subsequent CT scan during their follow up (mean follow up is 11.27 months) were included in this study. The diameter of both tunnels (femoral and tibial) were measured using MPR (multiplanar reconstruction) technique. Functional outcome was evaluated with International Knee Documentation Committee grade. Statistical analysis of the correlation between the diameter of the tunnels and IKDC grade were investigated. Results: The tibial and femoral bone tunnels were found to be significantly widened. There was no significant correlation between the diameter of bone tunnels and functional outcome (IKDC grade). Conclusion: Neither the diameter nor its widening during interval follow-up is correlated with functional outcome (IKDC Grade).

The drill wobble effect: oversizing the femoral tunnel during ACL reconstruction

ABSTRACTObjectives: In ACL reconstruction, autologous tendon graft can be attached to the femur, within a boney tunnel, using an Endobutton device. The ultimate aim being to achieve biological fixation and incorporation into the bone. Accurate bone tunnel diameter to match the tendon graft is vital to biologic incorporation and strength. The common technique of in sequence passing a guide wire, a cannulated 4.5 mm Endobutton drill, then a cannulated femoral socket drill causes the guidewire to lose cortical fixation and stability before the femoral socket drill is passed.The Objective of this study is to analyze this common technique of femoral socket creation and determine if it results in unintentionally oversizing the femoral socket due to femoral socket drill-wobble over a destabilised guide wire.Methods: 12 cadaveric femoral pairs equally divided between two groups underwent femoral socket creation in one of the two following sequences.Group 1: Guidewire, 4.5 mm endobutton drill, 8 mm femoral socket drill. Group 2: Guidewire, 8 mm femoral socket drill, 4.5 mm endobutton drill. The created femoral tunnels apertures and calibres were measured and then compared for accuracy between the two groups.Results: Passing the 4.5 mm drill before the 8 mm socket drill results in oversized tunnel apertures and calibres when compared to passing an 8 mm socket drill after the 4.5 mm drill has been passed (p<0.0001).Conclusion: To most precisely create an 8 mm femoral socket in ACL reconstruction, the 8 mm femoral socket reamer followed by the 4.5 mm should be passed over the guide wire to prevent guide wire destabilization and drill-wobble.

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.

The Effect of Graft Pretensioning on Bone Tunnel Diameter and Bone Formation After Anterior Cruciate Ligament Reconstruction in a Rat Model: Evaluation With Micro–Computed Tomography

Background: Moderate graft pretensioning in anterior cruciate ligament (ACL) reconstruction is paramount to restore knee stability and normalize knee kinematics. However, little is known about the effect of graft pretensioning on graft-to-bone healing after ACL reconstruction. Hypothesis: Moderate graft pretensioning will improve bone formation within the bone tunnel after ACL reconstruction, resulting in superior load to failure. Study Design: Controlled laboratory study. Methods: 67 male Sprague-Dawley rats underwent unilateral ACL reconstruction with a flexor digitorum longus tendon autograft. The graft was subjected to pretensioning forces of 0 N, 5 N, or 10 N. Custom-made external fixators were used for knee immobilization postoperatively. Rats were euthanized for biomechanical load-to-failure testing (n = 45) and micro–computed tomography (μCT) examination (n = 22) at 3 and 6 weeks after surgery. Three regions of each femoral and tibial bone tunnel (aperture, middle, and tunnel exit) were chosen for measurement of tunnel diameter and new bone formation. Results: Biomechanical tests revealed significantly higher load-to-failure in the 5-N graft pretensioned group compared with the 0- and 10-N groups at 3 weeks (8.58 ± 2.67 N vs 3.96 ± 1.83 N and 4.46 ± 2.62 N, respectively) and 6 weeks (16.56 ± 3.50 N vs 10.82 ± 1.97 N and 7.35 ± 2.85 N, respectively) after surgery (P < .05). The mean bone tunnel diameters at each of the 3 regions were significantly smaller in the 5-N group, at both the femoral and tibial tunnel sites, than in the 0- and 10-N groups (P < .05). At 3 and 6 weeks postoperatively, the bone mineral density, bone volume fraction, and connectivity density around the aperture and middle regions of the tibial bone tunnels were all significantly higher in the 5-N group compared with the 0- and 10-N groups (P < .05). In the aperture and middle regions of the femoral bone tunnels, pretensioning at either 5 or 10 N resulted in increased bone formation compared with the nonpretensioned group at 3 weeks postoperatively. No differences were found in bone formation between any of the 3 femoral tunnel regions at 6 weeks. Conclusion: Graft pretensioning can stimulate new bone formation and improve tendon-to-bone tunnel healing after ACL reconstruction. Clinical Relevance: Optimal graft pretensioning force in ACL reconstruction can improve bone tunnel healing. Further study is necessary to understand the mechanisms underlying the effect of graft pretensioning on healing at the bone-tunnel interface.

Correlation between fixation systems elasticity and bone tunnel widening after ACL reconstruction.

Femoral and tibial tunnel widening (TW) after ACL reconstruction is a phenomenon increasing talk in the literature. It is underlying biological and mechanical causes. The aim of this study was to evaluate the relationship between bone tunnel enlargement and two different ACL fixation systems. 40 patient underwent ACL reconstruction with hamstring; randomly divided into group A with 20 patients treated with stiff systems (femoral Rigidfix and tibial interference screw), and into group B, with 20 patients treated with morel elastic system (femoral and tibial Tight-rope). Evaluated postoperatively with knee MRI at 40 days, 3 months, 6 months to measure bone tunnel diameters widening. At 40 days tunnel widening between two groups shows no statistically difference. At 3 months postoperatively, femoral bone tunnel widening amounted on average to 1.84 mm in middle of tunnel and 1 mm at the mouth in joint in group A, and respectively 3.2 mm and 2.5 mm in group B (p<0.05). Tibial tunnel widening was 1.24 mm at the mouth in joint and 1.3 mm in middle in group A and respectively 2.26 mm and 2.43 mm in group B (p<0.05). At 6 months femoral tunnel widening amounted on average to 2.45 mm in middle and 1.35 mm at the mouth in joint in group A and respectively 3.5 mm and 2.7 mm in group B (p<0.01). Tibial tunnel widening amounted on average to 1.27 at mouth in joint and 1 mm in middle of tunnel in group A and respectively 2.6 mm and 2.3 mm in group B (p<0.01). This study results suggest elastic fixation system increases bone tunnel enlargement after ACL reconstruction with hamstring without correlation with worse clinical performance. IV.

The Correlation of Tunnel Position, Orientation and Tunnel Enlargement in Outside-in Single-Bundle Anterior Cruciate Ligament Reconstruction.

PurposeTunnel widening after anterior cruciate ligament (ACL) reconstruction is a frequently described phenomenon. The possible etiology is multi-factorial with some mechanical and biological factors. Among those, we intended to determine the relation between the location and orientation of the femoral tunnel and the femoral tunnel enlargement after outside-in single-bundle ACL reconstruction.Materials and MethodsA retrospective study including 42 patients who received single-bundle ACL reconstruction with the outside-in technique was conducted. Femoral and tibial tunnel locations were evaluated with the quadrant method and bird's-eye view using volume-rendering computed tomography. The angle and diameter of bone tunnel and the degree of tunnel enlargement were evaluated using standard radiographs.ResultsThe degree of femoral tunnel enlargements were 42% and 36% on the anteroposterior (AP) and lateral radiographs, respectively, and the degree of tibial tunnel enlargements were 22% and 23%, respectively. Shallower location of the femoral tunnel was significantly correlated with greater femoral tunnel enlargement on the AP radiograph (r=0.998, p=0.004) and the lateral radiograph (r=0.72, p=0.005) as was the higher location of the femoral tunnel on the AP radiograph (r=-0.47, p=0.01) and the lateral radiograph (r=-0.36, p=0.009) at 12 months after surgery.ConclusionsThis study revealed that more anterior and higher location and more horizontal orientation of the femoral tunnel in coronal plane could result in widening of the femoral tunnel in outside-in single-bundle ACL reconstruction.

Press-fit fixation using autologous bone in the tibial canal causes less enlargement of bone tunnel diameter in ACL reconstruction--a CT scan analysis three months postoperatively.

BackgroundBone tunnel enlargement is a phenomenon present in all anterior cruciate ligament (ACL)- reconstruction techniques. It was hypothesized that press-fit fixation using a free autograft bone plug reduces the overall tunnel size in the tibial tunnel.MethodsIn a prospective cohort study twelve patients who underwent primary ACL reconstruction using an autologous quadriceps tendon graft and adding a free bone block for press-fit fixation (PF) in the tibial tunnel were matched to twelve patients who underwent ACL reconstruction with a hamstring graft and interference screw fixation (IF). The diameters of the bone tunnels were analysed by a multiplanar reconstruction technique (MPR) in a CT scan three months postoperatively. Manual and instrumental laxity (Lachman test, Pivot-shift test, Rolimeter) and functional outcome scores (International Knee Documentation Committee sore, Tegner activity level) were measured after one year follow up.ResultsIn the PF group the mean bone tunnel diameter at the level of the joint entrance was not significantly enlarged. One and two centimeter distal to the bone tunnel diameter was reduced by 15 % (p = .001). In the IF group the bone tunnel at the level of the joint entrance was enlarged by 14 % (p = .001). One and two centimeter distal to the joint line the IF group showed a widening of the bone tunnel by 21 % (p < .001) One and two centimeter below the joint line the bone tunnel was smaller in the PF group when compared to the IF group (p < .001). No significant difference for laxity test and functional outcome scores could be shown.ConclusionThis study demonstrates that press-fit fixation with free autologous bone plugs in the tibial tunnel results in significantly smaller diameter of the tibial tunnel compared to interference screw fixation.

Bone Tunnel Diameter Measured with CT after Anterior Cruciate Ligament Reconstruction Using Double-Bundle Auto-Hamstring Tendons: Clinical Implications

ObjectiveTo evaluate the correlation between bone tunnel diameter after anterior cruciate ligament (ACL) reconstruction measured by computed tomography (CT) using multiplanar reconstruction (MPR) and stability or clinical scores.Materials and MethodsForty-seven patients (41 men and 6 women, mean age: 34 years) who had undergone ACL reconstruction with the double bundle technique using auto-hamstring graft and had subsequently received CT scans immediately after the surgery (T1: range, 1-4 days, mean, 2.5 days) and at a later time (T2: range, 297-644 days, mean, 410.4 days) were enrolled in this study. The diameter of each tunnel (two femoral and two tibial) at both T1 and T2 were independently measured using MPR technique by two radiologists. Stability and clinical scores were evaluated with a KT-2000 arthrometer, International Knee Documentation Committee objective scores, and the Lysholm score. Statistical analysis of the correlation between the diameter at T2 or the interval diameter change ratio ([T2 - T1] / T1) and clinical scores or stability was investigated.ResultsThe tibial bone tunnels for the anteromedial bundles were significantly widened at T2 compared with T1 (observer 1, 0.578 mm to 0.698 mm, p value of < 0.001; observer 2, 0.581 mm to 0.707 mm, p value of < 0.001). There was no significant correlation between the diameter at T2 and stability or clinical scores and between the interval change ratio ([T2 - T1] / T1) and stability or clinical scores (corrected p values for all were 1.0). Intraobserver agreement for measurements was excellent (> 0.8) for both observers. Interobserver agreement for measurement was excellent (> 0.8) except for the most distal portion of the femoral bone tunnel for anterior medial bundle in immediate postoperative CT, which showed moderate agreement (concordance correlation coefficient = 0.6311).ConclusionNeither the diameter nor its change ratio during interval follow-up is correlated with stability or clinical scores.

Reliability of a semi-automated 3D-CT measuring method for tunnel diameters after anterior cruciate ligament reconstruction: A comparison between soft-tissue single-bundle allograft vs. autograft

BackgroundPost-operative widening of tibial and/or femoral bone tunnels is a common observation after ACL reconstruction, especially with soft-tissue grafts. There are no studies comparing tunnel widening in hamstring autografts versus tibialis anterior allografts. The goal of this study was to observe the difference in tunnel widening after the use of allograft vs. autograft for ACL reconstruction, by measuring it with a novel 3-D computed tomography based method. MethodsThirty-five ACL-deficient subjects were included, underwent anatomic single-bundle ACL reconstruction and were evaluated at oneyear after surgery with the use of 3-D CT imaging. Three independent observers semi-automatically delineated femoral and tibial tunnel outlines, after which a best-fit cylinder was derived and the tunnel diameter was determined. Finally, intra- and inter-observer reliability of this novel measurement protocol was defined. ResultsIn femoral tunnels, the intra-observer ICC was 0.973 (95% CI: 0.922–0.991) and the inter-observer ICC was 0.992 (95% CI: 0.982–0.996). In tibial tunnels, the intra-observer ICC was 0.955 (95% CI: 0.875–0.985). The combined inter-observer ICC was 0.970 (95% CI: 0.987–0.917). Tunnel widening was significantly higher in allografts compared to autografts, in the tibial tunnels (p=0.013) as well as in the femoral tunnels (p=0.007). ConclusionsTo our knowledge, this novel, semi-automated 3D-computed tomography image processing method has shown to yield highly reproducible results for the measurement of bone tunnel diameter and area. This series showed a significantly higher amount of tunnel widening observed in the allograft group at one-year follow-up. Level of evidenceLevel II, Prospective comparative study.

ACL reconstruction in children: A transphyseal technique

The annual incidence of ACL tears is increasing steadily in pediatric patients. Chronic anterior instability causes meniscal lesions at a frequency that increases significantly with the injury-to-surgery interval. Conservative therapy, simple suturing, and isolated extra-articular tendon reconstruction are associated with high failure rates. Intra-articular arthroscopy-assisted tendon reconstruction is a good treatment method, although several different techniques have been described. We used a transphyseal technique with a hamstring tendon graft to treat 14 knees in 13 patients with a mean age of 13 years and 7 months. Mean injury-to-surgery interval was 6 months. Strict compliance with technical rules is required when using this technique. Bone tunnel diameter must not exceed 8mm. Bone tunnels must be as vertical and central as possible. The fixation material must not bridge the physis (at the femur, cortical fixation; and at the tibia, fixation using a resorbable screw no longer than 25mm combined with a staple). Meniscal lesions were present in half the knees and meniscal preservation considered mandatory. Conservative treatment of concomitant lesions was performed routinely. After a mean follow-up of 15 months, no recurrent tears or revision procedures for meniscectomy had been recorded. The IKDC grade was A or B in 93% of knees. The mean subjective IKDC score was 83.3 and the Lysholm score was in the excellent or good range in 93% of knees. Of the 14 knees, 2 exhibited signs suggesting femoral epiphysiodesis, with 4° of valgus deformity compared to the contra-lateral knee and no clinical consequences. Transphyseal reconstruction with open physes conducted in strict compliance with technical rules can be performed to control the instability and preserve the menisci. Nevertheless, this technique carries a risk of epiphysiodesis, chiefly at the femur.

Biomechanical Consequences of Coracoclavicular Reconstruction Techniques on Clavicle Strength

Background: Lateral clavicle fractures have been reported after coracoclavicular (CC) ligament reconstructions with bone tunnels through the clavicle. Purpose: To biomechanically compare clavicle strength following 2 common CC reconstruction techniques with different bone tunnel diameters. Study Design: Controlled laboratory study. Methods: Testing was performed on 2 groups of matched-pair cadaveric clavicles. Clavicles were prepared with either 2.4-mm tunnels and cortical fixation button (CFB) devices or 6.0-mm tunnels with hamstring tendon grafts (TGs) and tenodesis screws; contralateral clavicles were left intact. A 3-point bending load was applied to the distal clavicles at a rate of 15 mm/min until failure. Ultimate failure load and anterior-posterior width of the clavicles 45 mm medial from the lateral border were recorded. Strength reduction was determined as the percentage reduction in ultimate failure load between paired intact and surgically prepared clavicles. Relative tunnel size was determined as the quotient of tunnel diameter and clavicle width, reported as a percentage. Results: The TG technique significantly reduced clavicle strength relative to intact (P = .011) and caused significantly more strength reduction (mean, −30.7%; range, 8.1% to −62.5%) than the CFB technique (mean, −3.8%; range, 34.2% to −28.1%; P = .031). The CFB technique was not significantly different from intact (P = .314). There was a significant correlation between clavicle width and strength reduction (τ = −0.36, P = .04) and between relative tunnel size and strength reduction (τ = 0.51, P = .005). Conclusion: The TG reconstruction technique with 6.0-mm tunnels, grafts, and tenodesis screws caused significantly more reduction of clavicle strength compared with the CFB technique with 2.4-mm tunnels and CFB device. Additionally, relative tunnel width correlated highly with the strength reduction. Clinical Relevance: This information can influence intraoperative decision making based on the individual clavicle width and might influence postoperative treatment protocols. Large bone tunnels may predispose patients to clavicle fractures after anatomic CC reconstructions.

Anterior cruciate ligament (ACL) autograft reconstruction with hamstring tendons: clinical research among three rehabilitation procedures

To compare the effects of the three rehabilitation procedures following anterior cruciate ligament (ACL) autograft reconstruction with hamstring tendons. An observational and retrospective case-controlled series. The Department of Sports Medicine, Shenzhen Second People Hospital, Shenzhen, PR China. Forty-five patients who were made to undergo ACL reconstructions by using quadrupled semitendinosus and gracilis tendons were divided into three groups: accelerated rehabilitation procedures group, aggressive rehabilitation procedures group, and self-made rehabilitation procedures group. The knee range of motion, thigh perimeter, IKDC score, and bone tunnel diameter in 3D-CT films were evaluated 3 and 6months and 1year later. The knee range of motion and thigh perimeter of group A were higher than those of group B and group C at 3, 6, and 12months. IKDC scores of group C were better than those of groups A and B. The bone tunnel widening with group B was larger than that with groups A and C, and the differences were statistically significant (P<0.05). Early rehabilitation is beneficial for restoration of knee function after ACL reconstruction. Moderate procedure is better than accelerated procedure.

A comparative study of tunnel enlargement after anterior cruciate ligament reconstruction with autologous and allogenic tendons

Objective To investigate the changes of bone tunnel and differences of clinical outcomes after anterior cruciate ligament (ACL) reconstruction with hamstring tendons from autografts and allografts. Methods The study involved in 61 patients with ACL injury undergone arthroscopic ACL reconstruction from June 2008 to November 2009.According to ACL graft differences,61 patients were assigned to two groups,ie,Group A ( reconstruction with tendon allografts,n =27 ) and Group B ( reconstruction with tendon autografts,n =34).MRI examination was performed one week and 6-12 months post-operatively to measure the sagittal bone tunnel diameters at the aperture location,at the location of 1cm away from the aperture and at the widest location of tunnel.Taking the bone tunnel diameter at each location one week post-operatively as the measurement criteria,the differences of bone tunnel diameters at each corresponding location were analyzed statistically.Lysholm score was used to evaluate the clinical effects in the two groups. Results Group A and B were followed up for average 8.4 months and 8.5 months,respectively.Pre-operative clinical data of the two groups had no significant difference.MRI follow-up showed that the tunnel diameters at femoral side and tibial side both had different degree of enlargement.Meanwhile,the enlargement degree at the tibial side was larger than that at the femoral side,with no statistical differences of the two groups regarding tunnel enlargement of the three measurement locations at femoral and tibial sides.Joint stability in all patients was good.The two groups showed no significant difference in Lysholm score after operation ( P ＞ 0.05 ). Conclusions Graft difference is a factor for bone tunnel enlargement after ACL surgery.Autologous and allogenic tendons show no difference in their role in bone tunnel enlargement after ACL surgery or correlation with clinical effects. Key words: Anterior cruciate ligament; Arthroscopy; Transplantation; Knee joint

Improved outcomes after anterior cruciate ligament reconstruction with quadrupled hamstring autografts and additional bone plug augmentation at five year follow-up

Hybrid fixation has been proposed to improve outcomes of anterior cruciate ligament (ACL) reconstructions. This study evaluated midterm outcomes after transfemoral graft fixation using either a conventional or a modified technique using additional bone plug augmentation (BPA) of the femoral tunnel aperture. Seventy-one consecutive patients undergoing ACL reconstruction using a quadrupled hamstring autograft with transfemoral graft fixation and tibial interference screw fixation were included. Of these, 56 patients could be followed up 61months (range 52-69months) after ACL reconstruction both clinically and by magnetic resonance imaging (group A, conventional technique, n = 34; group B, modified technique, n = 22). Anteroposterior (AP) laxity measurements and International Knee Documentation Committee (IKDC), Lysholm and Tegner activity scoring were performed, while imaging included assessment of bone tunnel diameters, graft condition and graft filling at the femoral bone tunnel aperture. Patients with additional BPA had a significantly higher degree of graft filling at the femoral bone tunnel aperture (p = .0135) and 'healthier' grafts (p = .0495). They also tended to display less AP laxity difference in terms of mean differences and total patient numbers. Lysholm, IKDC and Tegner activity index scores and bone tunnel diameters were not significantly different. Additional BPA is an easy-to-perform, cheap and safe manoeuvre, which has the capacity to improve morphological and clinical outcomes at five year follow-up. However, femoral tunnel widening is unaffected by additional BPA.

Close-looped graft suturing improves mechanical properties of interference screw fixation in ACL reconstruction

In anterior cruciate ligament reconstruction with looped soft-tissue grafts, an interference screw is frequently used for tibial fixation. This study compared three alternatives thought to improve the initial mechanical properties of direct bioabsorbable interference screw fixation: suturing the graft to close the loop, adding a supplementary staple, or increasing the oversize of the screw diameter relative to the bone tunnel from 1 to 2mm. Twenty-eight porcine tibiae and porcine flexor digitorum profundus tendons were randomized into four testing groups: a base fixation using 10-mm-diameter screw with open-looped graft, base fixation supplemented by an extracortical staple, base fixation but closing the looped graft by suturing its ends, and base fixation but using an 11-mm screw. Graft and bone tunnel diameters were 9mm in all specimens. Constructs were subjected to cyclic tensile load and finally pulled to failure to determine their structural properties. The main mode of failure in all groups was pull-out of tendon strands after slippage past the screw. The sutured graft group displayed significantly lower residual displacement (mean value reduction: 47-67%) and higher yield load (mean value increase: 38-54%) than any alternative tested. No other statistical differences were found. Suturing a soft-tissue graft to form a closed loop enhanced the initial mechanical properties of tibial fixation with a bioabsorbable interference screw in anterior cruciate ligament reconstructions using a porcine model, and thus, this may be an efficient means to help in reducing post-operative laxity and early clinical failure. No mechanical improvement was observed for an open-looped tendon graft by adding an extracortical staple to supplement the screw fixation or by increasing the oversize of the screw to tunnel diameter from 1 to 2mm.

Inferior tendon graft to bone tunnel healing at the tibia compared to that at the femur after anterior cruciate ligament reconstruction

BackgroundTunnel widening after anterior cruciate ligament (ACL) reconstruction (ACLR) is commonly reported without a clear understanding of the mechanism. This study aimed to quantify the spatiotemporal change of the newly formed bone mass, bone tunnel diameter, and area along both bone tunnels using micro-computed tomography (μCT) and correlated the result with histology. MethodsACLR was performed in 24 rabbits. At baseline and weeks 2, 6, and 12, the juxta-articular, middle, and exit segments of both tunnels were harvested for μCT and histological evaluation. ResultsμCT and histology revealed signifi cant bone tunnel and graft–bone tunnel healing, respectively, only at week 6 after reconstruction. Despite this, the mean tunnel diameter and area remained relatively unchanged with time. The newly formed bone mass [new bone volume/total bone volume (BV/TV) ratio] and its bone mineral density (BMD) were both higher, whereas the mean tunnel diameter and area were signifi cantly smaller at the femoral tunnel compared to those at the tibial tunnel at weeks 6 and 12 and at week 12, respectively. These were consistent with histological fi ndings, which showed inferior graft remodeling and integration at the tibial tunnel at weeks 6 and 12. The BV/TV increased, whereas the mean tunnel diameter and area decreased toward the exit segment of both tunnels. However, whereas better histological healing occurred at the femoral exit segment, poorer graft remodeling and Sharpey’s fi ber formation occurred at the tibial exit segment. ConclusionsPoor healing was observed during the initial 6 weeks, particularly that of the tibia, after ACLR. Bone resorption was rapid during healing, resulting in unchanged tunnel diameter and area with time.

Observations on Bone Tunnel Enlargement After Double-Bundle Anterior Cruciate Ligament Reconstruction

The purpose of this study was to determine the amount of tibial and femoral bone tunnel enlargement after double-bundle anterior cruciate ligament (ACL) reconstruction. Twenty-five consecutive patients undergoing primary double-bundle hamstring ACL reconstruction were included in a prospective case series. Femoral fixation was performed by means of 2 EndoButton CL devices (Smith & Nephew Endoscopy, Andover, MA), and tibial fixation was done with 2 bioresorbable interference screws. Magnetic resonance imaging (MRI) was performed in all patients at a mean of 12.3 months postoperatively. Tunnel enlargement was determined by digitally measuring the widths perpendicular to the long axis of the anteromedial (AM) and posterolateral (PL) tunnels on an oblique coronal and axial plane. The MRI measurements were compared with the intraoperative drill diameter. The mean tibial AM bone tunnel diameter increased from 0.74 to 1.06 cm, and the mean PL diameter increased from 0.60 to 0.89 cm. The mean femoral AM bone tunnel diameter increased from 0.71 to 0.97 cm, and the mean PL diameter increased from 0.58 to 0.85 cm. Bone tunnel enlargement was 43% (P = .001) for both tibial tunnels and 35% (P = .001) versus 48% (P < .001) for the femoral AM bone tunnel versus the PL femoral bone tunnel. On the tibial side, communication of the bone tunnels occurred in 41% of patients. This study shows significant tibial and femoral bone tunnel enlargement on MRI after 4-tunnel double-bundle ACL reconstruction 1 year postoperatively. In 41% of patients separate tibial bone tunnel measurements were impossible because of tunnel communication caused by intraoperative bone tunnel drilling, screw contact, or postoperative bone tunnel enlargement. On the femoral side, no bone tunnel communication occurred. The short-term clinical results were good and were not influenced by tunnel communication. Level IV, therapeutic case series.

Correlation of bone tunnel diameter with quadrupled hamstring graft fixation strength using a biodegradable interference screw

Purpose: The purpose of this study was to determine whether the ultimate load at failure of a quadrupled hamstring tendon graft (QHT) fixed with a biodegradable interference screw is improved with a more precise match of the bone tunnel diameter to the diameter of the QHT. Type of Study: Biomechanical testing. Methods: In group A, 8 cadaver knees with a mean age of 69.4 years (range, 60 to 76) were used. QHT graft diameters were measured using sleeves in standard 1.0-mm increments, with matching bone tunnels drilled in 1.0-mm increments. In group B, 9 cadaver knees, with a mean age of 66.5 (53 to 81) were used. Grafts were measured using sleeves in 0.5-mm increments and matching bone tunnels in 0.5-mm increments were drilled. In both groups, the QHT grafts were fixed with a biodegradable interference screw (BioScrew, Linvatec, Largo, FL) in both the tibia and the femur. Tendon interference fixation was tested to failure using a material testing device that tensioned the grafts directly in line with the bone tunnels. Bone mineral density was measured using dual photon absorptimetry for the metaphyseal area of the tibias and femora in the area of interference screw fixation. Results: Femoral maximum load at failure significantly improved from 341 N in the 1.0-mm group to 530 N (P <.05) in the 0.5-mm group; the tibial maximum load at failure improved from 221 N to 308 N (P =.35). Conclusions: Fixation strength results of this study suggest that commercially available instrumentation could be improved with sleeves and reamers available in 0.5-mm increments.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 8 (October), 2002: pp 901–907

Tunnel expansion after hamstring anterior cruciate ligament reconstruction with 1-incision EndoButton femoral fixation

Summary: In this study, we compared a study group of 20 patients who underwent anterior cruciate ligament (ACL) reconstruction with hamstring autografts using a 1-incision endoscopic technique verses a control group of 20 patients using a 2-incision technique. The patient groups were compared based on increase of bone tunnel diameter seen radiographically, physical examination, and arthrometer measurements. The 1-incision technique differed from the 2-incision technique in 2 ways: an EndoButton femoral fixation system and drilling of the femoral tunnel through the tibial tunnel (transtibial). This study shows that the majority of tunnel diameter measurements for the 1-incision ACL reconstruction technique were greater than those of the 2-incision ACL reconstruction technique using autologous hamstring tendons, at both 3 and 12 months of follow-up. Between 3 and 12 months follow-up, there was no statistical differences in tunnel enlargement between the 2 groups of patients. The measured tunnel enlargement, therefore, would have occurred before the 3-month follow-up. There was no significant difference in the Lachman or arthrometer testing in either group of patients at the termination of this study. This indicates that, although tunnel expansion is significant, the increased expansion is not related to increased knee laxity in the first year.Arthroscopy: The Journal of Arthroscopic and Related surgery, Vol 16, No 7 (October), 2000: pp 707–714