Prediction of quadruple hamstring graft diameter for anterior cruciate ligament reconstruction by anthropometric measurements

Background:

The literature is scanty regarding the anthropometric predictors on the diameter of quadruple hamstring graft obtained in anterior cruciate ligament (ACL) reconstruction in Indian population. Minimum diameter of the graft for ACL reconstruction should be >7 mm to preclude failure. The objective of this study was to assess the prediction of the hamstring graft diameter by several anthropometric parameters including age, thigh circumference, weight, height and body mass index (BMI).

Materials and Methods:

46 consecutive patients who had undergone ACL reconstruction by the same surgeon using quadruple hamstring grafts were evaluated. The age, thigh circumference of the normal side, height, weight and BMI were recorded preoperatively and Pearson correlation was done using these parameters with graft diameter measured intraoperatively. Regression analysis in a stepwise manner was undertaken to assess the influence of individual anthropometric parameters on the graft diameter.

Results:

There were 44 males and 2 females. Mean age was 29.4 years, mean height was 172.6 cm, mean weight was 70.9 kg, mean BMI was 23.8 kg/m², mean thigh circumference was 47.1 cm and mean graft diameter was 7.9 mm. There was a positive correlation individually between the thigh circumference and graft diameter obtained (r = 0.8, P < 0.01, n = 46), and between the height and graft diameter (r = 0.8, P < 0.01, n = 46). On the regression analysis thigh circumference and height were found to be significant predictors of graft diameter giving the following equation: Graft diameter (mm) = 0. 079 height (cm) +0.068 thigh circumference (cm) −9.031.

Conclusion:

Preoperatively using the above equation if graft diameter came out to be <7 mm then alternate options of graft material must be kept in mind in order to prevent failure.     

Simulated graft recession in endoscopic ACL reconstruction: influence on graft strain

Eight fresh cadaveric knee specimens underwent arthroscopic-assisted ACL reconstruction to examine the influence of femoral graft recession on graft strain pattern. Length changes between tibial origin and femoral insertion (simulating graft strain or isometry pattern) were measured throughout knee motion (0 degrees-90 degrees) with a simulated ACL construct. Measurements were taken at the "endo" position (replicating the normal endoscopic position) and in progressive 1.5-mm increments proximally within the femoral tunnel (mimicking femoral graft recession). After recession up to a maximum of 15 mm, a block was placed anterior to the "recessed" graft construct (simulating placement of bone graft anterior to the recessed graft) and strain patterns were remeasured. Graft strain patterns were altered with as little as 1.5 mm recession in two of eight specimens. Compared to the "endo" position, all specimens showed a statistically significant decrease in strain by 3 mm of graft recession (P<.001 for 7 of 8, and P=.0138 for 1 of 8). A direct relationship exists between graft placement and ACL strain patterns, with more proximal graft "recession" adversely influencing normal graft strain. Bone graft placement anterior to the recessed graft restores strain patterns to those seen at the normal "endoscopic" position.     

Premature hamstring graft amputation during harvesting in ACL reconstruction

IntroductionThere are some possible complications during or after hamstring graft harvesting such as premature graft amputation, medial collateral ligament injury and infrapatellar branch of the saphenous nerve injury. Premature graft amputation can occur by inadequate removal of the accessory branches of the hamstring tendons, poor surgical technique and/or too sharp tendon stripper. In this study, we report a case of premature hamstring graft amputation due to degeneration caused by osteochondroma at the posteromedial aspect of the proximal tibia.Case presentationWe reported the case of a 28-year-old Thai male who had an ACL injury was scheduled for ACL reconstruction. In this case, we had planned to use a hamstring graft for double-bundle ACL reconstruction. During the gracilis tendon harvesting, the graft was prematurely amputated by a tendon stripper at the level of the osteochondroma. The premature graft amputation was sent for pathology, which showed degenerated tissue.ConclusionIn cases of osteochondroma at the posteromedial aspect of the proximal tibia, it is a chance of premature hamstring graft amputation. We suggest removing the osteochondroma before harvesting the tendon grafts to avoid the risk of premature graft transection.     

Comparison of the ACL and ACL graft forces before and after ACL reconstruction an in-vitro robotic investigation

Background?Long-term follow-up studies have indi-cated that there is an increased incidence of arthrosis following anterior cruciate ligament (ACL) reconstruc-tion, suggesting that the reconstruction may not repro-duce intact ACL biomechanics. We studied not only the magnitude but also the orientation of the ACL and ACL graft forces

Methods?10 knee specimens were tested on a robotic testing system with the ACL intact, deficient, and recon-structed (using a bone-patella tendon-bone graft). The magnitude and orientation of the ACL and ACL graft forces were determined under an anterior tibial load of 130?N at full extension, and 15, 30, 60, and 90° of flexion. Orientation was described using elevation angle (the angle formed with the tibial plateau in the sagit-tal plane) and deviation angle (the angle formed with respect to the anteroposterior direction in the transverse plane)

Results?ACL reconstruction restored anterior tibial translation to within 2.6?mm of that of the intact knee under the 130-N anterior load. Average internal tibial rotation was reduced after ACL reconstruction at all flexion angles. The force vector of the ACL graft was significantly different from the ACL force vector. The average values of the elevation and deviation angles of the ACL graft forces were higher than that of the intact ACL at all flexion angles

Interpretation?Contemporary single bundle ACL reconstruction restores anterior tibial translation under anterior tibial load with different forces (both magni-tude and orientation) in the graft compared to the intact ACL. Such graft function might alter knee kinematics in other degrees of freedom and could overly constrain the tibial rotation. An anatomic ACL reconstruction should reproduce the magnitude and orientation of the intact ACL force vector, so that the 6-degrees-of-freedom knee kinematics and joint reaction forces can be restored.     

Comparison of the ACL and ACL graft forces before and after ACL reconstruction: an in-vitro robotic investigation

Background Long-term follow-up studies have indi-cated that there is an increased incidence of arthrosis following anterior cruciate ligament (ACL) reconstruc-tion, suggesting that the reconstruction may not repro-duce intact ACL biomechanics. We studied not only the magnitude but also the orientation of the ACL and ACL graft forces

Methods 10 knee specimens were tested on a robotic testing system with the ACL intact, deficient, and recon-structed (using a bone-patella tendon-bone graft). The magnitude and orientation of the ACL and ACL graft forces were determined under an anterior tibial load of 130 N at full extension, and 15, 30, 60, and 90° of flexion. Orientation was described using elevation angle (the angle formed with the tibial plateau in the sagit-tal plane) and deviation angle (the angle formed with respect to the anteroposterior direction in the transverse plane)

Results ACL reconstruction restored anterior tibial translation to within 2.6 mm of that of the intact knee under the 130-N anterior load. Average internal tibial rotation was reduced after ACL reconstruction at all flexion angles. The force vector of the ACL graft was significantly different from the ACL force vector. The average values of the elevation and deviation angles of the ACL graft forces were higher than that of the intact ACL at all flexion angles

Interpretation Contemporary single bundle ACL reconstruction restores anterior tibial translation under anterior tibial load with different forces (both magni-tude and orientation) in the graft compared to the intact ACL. Such graft function might alter knee kinematics in other degrees of freedom and could overly constrain the tibial rotation. An anatomic ACL reconstruction should reproduce the magnitude and orientation of the intact ACL force vector, so that the 6-degrees-of-freedom knee kinematics and joint reaction forces can be restored.     

Influence of the diameters of tendon graft and bone tunnel in hamstring ACL reconstruction. A bovine model

In an animal model of Anterior Cruciate Ligament reconstruction by hamstring tendons and 8mm diameter biodegradable interference screws, we aimed to investigate whether pull out forces and failure modes were influenced by changing tendon and bone tunnel diameters. Three groups of 10 calf tibiae each were prepared with 8, 9 and 10mm diameter proximal tunnels fitted respectively with 8, 9 and 10mm diameter tendon grafts. Mean +/- SD pull out force was 607.9 +/- 191.5N in the 8mm group, 494.2 +/- 206.2N in the 9mm group and 530.4 +/- 212.5N in the 10mm group. These differences were not significant at t-test. 8mm specimens failed by tendon rupture, 10mm specimens failed by screw pull out and 9mm specimens failed in both ways. In this ACL reconstruction model, safe pull out forces were achieved by fixing tendon grafts to bone by 8 mm absorbable interference screws regardless of tendon and bone tunnel diameter.     

Relationship between anthropometric measurements and hamstring autograft diameter in anterior cruciate ligament reconstruction

The role of anthropometric measurements in the prediction of hamstring autograft size remains unclear. In this internal review board - approved study, we evaluated medical records for patients receiving anterior cruciate ligament (ACL) reconstruction with hamstring autograft at our institution between 2006 and 2008. One hundred and thirty-two patients received hamstring autografts. Correlation coefficients and step-wise multiple linear regression analysis were used to determine the relationships between sex, age, height, body mass index (BMI), and hamstring graft diameter. Women had significantly smaller grafts than men (P < .00001). Twenty-four patients had grafts less than 7 mm in diameter and 18 of those patients were female. Age and BMI did not correlate with graft diameter in women. Height correlated to graft diameter in women (P = .002, R(2) = 0.14). Women shorter than 65 in had significantly smaller graft diameters (mean [SD], 6.94 [0.45] mm), than those women 65 in and taller (mean [SD], 7.20 0.49] mm; (P = .03). Age and height did not correlate with graft size in men. BMI greater than 25 kg/m(2) correlated with larger graft diameter, but BMI less than 18 kg/m(2) did not predict graft sizes less than 7 mm. Therefore, alternative graft options should be considered in women less than 65 in tall.     

ACL reconstruction using an abnormally thick autogenous patellar tendon graft.

This prospective study measured the patellar tendon thickness of 543 patients who underwent anterior cruciate ligament (ACL) reconstruction with an autogenous bone-patellar tendon-bone graft to document the normal range of patellar tendon thickness and to determine if using thicker than normal patellar tendons as an ACL graft source affected postoperative outcome. The postoperative results of 55 patients who underwent ACL reconstruction with a patellar tendon > or =7 mm thick (thick tendon group) were compared with those of 488 patients who underwent ACL reconstruction with a patellar tendon < or =6 mm thick (normal tendon group). 5 mm (4.5 mm in women and 5.3 mm in men) with a range of 3-11 mm (3-7 mm in women and 3-11 mm in men). There was no statistically significant difference in the postoperative KT-1000 arthrometer mean manual maximum difference (2.0 mm for grafts < or =6 mm thick and 1.9 mm for grafts > or =7 mm thick), postoperative quadriceps muscle strength scores, modified Noyes questionnaire subjective scores (mean of 91 points for grafts < or =6 mm thick and 92 points for grafts > or =7 mm thick), or postoperative stability and pain scores. These results indicate that an abnormally thick patellar tendon should not preclude the use of this involved tendon as a graft source for ACL reconstruction.     

Tendon graft fixation in ACL reconstruction: in vitro evaluation of bioabsorbable tenodesis screw

BACKGROUND: Conventional ACL reconstruction requires sufficient tibial bone quality for secure graft fixation. We evaluated the mechanical characteristics of a supplemental tenodesis screw in cadaveric specimens. MATERIAL AND METHODS: One group of 7 specimens from 7-paired tibiae was randomly assigned to undergo tibialis anterior tendon graft-bone tunnel fixation with a bioabsorbable interference screw, using conventional ACL reconstruction techniques. The other group of 7 specimens underwent the same procedure supplemented with a bioabsorbable tenodesis screw. All specimens were subjected to pullout testing on a servo hydraulic device. RESULTS: Specimens in the supplemental fixation group had double the load to failure (tenodesis = 467 (SD 184) N, control group = 223 (SD 66) N, p = 0.02) and were also one-third stiffer (tenodesis = 31 (SD 13) N/mm, control group = 21 (SD 6) N/mm, p = 0.03) than the specimens in the conventional fixation group. INTERPRETATION: Supplemental bioabsorbable tenodesis screw fixation may be advantageous for primary reconstruction in patients with low tibial bone mineral density or during revision procedures. By providing secure soft tissue graft-tibia fixation during the early phase after ACL reconstruction, supplemental tenodesis fixation may enable patients to participate safely in more intense, early rehabilitation.     

Graft failure versus graft fixation in ACL reconstruction: histological and immunohistochemical studies in rabbits

The causes of graft failure after anterior cruciate ligament (ACL) reconstruction are multifactorial including the methods of graft fixation. The purpose of this study was to examine the ACL graft failure in three different methods of graft fixations including interference screw fixation, suture-post fixation and combined interference screw and suture-post fixation. We hypothesized that the fixation method after ACL reconstruction can affect the graft healing in tibial tunnel. Eighteen New Zealand white rabbits were categorized into three groups according to the method of fixation in unilateral ACL reconstruction with long digital extensor autograft. Histological examination demonstrated that the combined fixation and suture-post fixation groups showed significantly better integration between tendon and bone (P = 0.04). In immunohistochemical analysis, the combined fixation and suture-post fixation groups showed significantly higher BMP-2 and VEGF expressions than interference screw (P < 0.01). The tendon–bone healing after ACL reconstruction was affected by the method of graft fixation. Combined fixation with interference screw and suture-post reduced graft-tunnel micromotion and improved the graft healing in tibial tunnel.     

The anatomy of the ACL and its importance in ACL reconstruction

The anterior cruciate ligament (ACL) anatomy is very significant if a reconstruction is attempted after its rupture. An anatomic study should have to address, its biomechanical properties, its kinematics, its position and anatomic correlation and its functional properties. In this review, an attempt is made to summarize the most recent and authoritative tendencies as far as the anatomy of the ACL, and its surgical application in its reconstruction are concerned. Also, it is significant to take into account the anatomy as far as the rehabilitation protocol is concerned. Separate placement in the femoral side is known to give better results from transtibial approach. The medial tibial eminence and the intermeniscal ligament may be used as landmarks to guide the correct tunnel placement in anatomic ACL reconstruction. The anatomic centrum of the ACL femoral footprint is 43 % of the proximal-to-distal length of lateral, femoral intercondylar notch wall and femoral socket radius plus 2.5 mm anterior to the posterior articular margin. Some important factors affecting the surgical outcome of ACL reconstruction include graft selection, tunnel placement, initial graft tension, graft fixation, graft tunnel motion and healing. The rehabilitation protocol should come in phases in order to increase range of motion, muscle strength and leg balance, it should protect the graft and weightbearing should come in stages. The cornerstones of such a protocol remain bracing, controlling edema, pain and range of motion. This should be useful and valuable information in achieving full range of motion and stability of the knee postoperatively. In the end, all these advancements will contribute to better patient outcome. Recommendations point toward further experimental work with in vivo and in vitro studies, in order to assist in the development of new surgical procedures that could possibly replicate more closely the natural ACL anatomy and prevent future knee pathology.     

ACL reconstruction and the implication of its tibial attachment for stability of the joint: anthropometric and biomechanical study

The planar topography of the anterior cruciate ligament (ACL) insertion was investigated and correlated to the use of the double-bundle/double tibial tunnel ACL reconstruction technique within the ACL tibial insertion area. The anteroposterior and mediolateral length of the tibial ACL attachment and the distances of the tibial insertion area from the anterior and posterior tibial borders were measured and the stability of the joint was tested using the double-bundle/double tibial tunnel ACL reconstruction technique. The anteroposterior length, 19.54 mm in men and 17.36 mm in women, of the ACL insertion, averaged approximately 40% of the total intercondylar anteroposterior dimension of the plateau. This broad distribution of insertion fibres ensures ligament tension and hence joint stability. The reported anteroposterior broad insertion of ACL fibres to the tibia is not sufficiently reproduced by the use of one or more bundles having a common tibial tunnel for the ACL reconstruction. In our view, this might be better achieved with two different bundles, with separate tunnels, and independent tensioning in different knee angles. This technique might achieve better results in human knee stability as opposed to other reported techniques.

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Résumé Une étude topographique de l’insertion du ligament croisé antérieur a recherchée une corrélation avec la technique du double tunnel/ double brin au niveau de la zone d’insertion tibiale. Les dimensions antéro-postérieure et médio-latérale de l’insertion tibiale ainsi que les distances entre les bords antérieur et postérieur du tibia et cette zone d’insertion étaient étudiées. La stabilité articulaire était testée après reconstruction par la technique du double brin avec double tunnel. La longueur antéro-postérieure de l’insertion - 19,54 mm chez l’homme et 17,36 chez la femme - représente approximativement 40% de la dimension antéro-postérieure du plateau tibial dans la région inter-condylienne. Cette distribution étendue de l’insertion des fibres assure la tension ligamentaire et en conséquence la stabilité articulaire. Cette insertion étendue n’est pas reproduite par l’utilisation d’un ou plusieurs brins passés dans un seul tunnel tibial. Nous pensons que cela peut être atteint en utilisant 2 brins et 2 tunnels avec une mise en tension indépendante dans les différentes positions du genou. Cette technique devrait donner de meilleurs résultats que les techniques habituellement proposées.

     

Influence of vein size (diameter) on infrapopliteal reversed vein graft patency

We reviewed 239 infrapopliteal reversed greater saphenous vein graft bypasses placed for critical ischemia over a 7-year period to determine the influence of vein diameter on graft patency and limb salvage. Grafts were assigned to four groups based on the minimum external diameter measured during operation: less than 3.0 mm, n = 18; 3.0 mm, n = 59; 3.5 mm, n = 67; and greater than or equal to 4.0 mm, n = 145. A pattern of increasing graft patency and limb salvage among the four groups was noted as the minimum external diameter increased from less than 3.0 mm to greater than or equal to 4.0 mm. When compared to the larger grafts greater than or equal to 4.0 mm, primary graft patency was significantly lower both for less than 3.0 mm grafts (0% for less than 3.0 mm vs 65% for greater than or equal to 4.0 mm at 3 years, p less than 0.001) and for long (greater than 45 cm) 3.0 mm grafts (38% for long 3.0 mm vs 75% for greater than or equal to 4.0 mm at 2 years, p less than 0.005). All 3.5 mm and short (less than 45 cm) 3.0 mm grafts had patency rates similar to greater than or equal to 4.0 mm veins. Thus long 3.0 mm and all less than 3.0 mm reversed saphenous vein grafts should be considered at high risk for failure. Veins with fibrotic, thick-walled segments identified during operation (n = 19) had patency rates significantly lower than nonfibrotic veins (n = 270; p less than 0.01), and this may play a role in the failure of some less than 3.0 mm minimum external diameter vein grafts.     

Variability of tunnel positioning in ACL reconstruction

Introduction

Since tunnel positioning is one of the key factors in anterior cruciate ligament (ACL) reconstruction and the variability of tunnel positioning in ACL reconstruction has so far never been analyzed, the objective of this study was to determine the inter- and intra-observer variability of tibial and femoral tunnel positioning in ACL reconstruction.

Materials and methods

In an operating room setup, 13 surgeons were asked to identify the tunnel positions in one and the same ACL-deficient cadaver knee. Using a fluoroscopic based ACL navigation system, tunnel positions were digitally measured in a test/re-test scenario. For variability analysis mean positions, standard deviations and range were calculated as well as differences between test/re-test positions.

Results

The intraobserver analysis showed a tibial variability of 3.3 mm (SD 2.1, range 7.5 mm) and a femoral variability of 2.0 mm (SD 1.6 mm, range 6.8 mm). The interobserver variability of the tibial tunnel positions was 3.2 mm (SD) with a range of 18.3 mm and a femoral variability of 3.7 mm (SD) with a range of 13.2 mm.

Conclusions

This study demonstrates that a reasonable inter- and intra-observer variability in ACL tunnel positioning exists even among experienced surgeons. Although deviations of 2–3 mm may seem to be acceptable at first sight, a range of up to 18.3 mm indicates that outliers exist, which can cause graft failure. More reliable reconstruction techniques should be developed to reduce the variability in tunnel positioning.     

ACL reconstruction by bone-patellar tendon-bone graft: mechanical evaluation of the elastic modulus and failure modes

The aim of this study was to apply an engineering approach to study the biomechanical behaviour of both native and reconstructed anterior cruciate ligaments (ACL) under tensile test, simulating the primary stability of the reconstructed ACL in the immediate postoperative period, when the bone callus has not formed yet. We used the bovine bone-patellar tendon-bone grafts to reconstruct ACL in bovine knees. The grafts were fixed by means of titanium interference screws and titanium transverse compressive screws. We tested 18 native and 18 reconstructed ligaments (7 with interference screws and 11 with transverse compressive screws). We applied mechanical tension at a 500 mm/min strain rate, and observed the mode of failure. The data analysis confirmed the different behaviour recorded in load elongation curves, a difference enhanced in stress-strain curves for both fixation methods. The stress-strain patterns for the interference screw and for the native ligament were quite similar.     

Biomechanical study of ACL reconstruction grafts

There are no published studies describing the strength quadrupled gracilis tendon alone and quadrupled semitendinosus tendon alone in the configuration used for anterior cruciate ligament (ACL) reconstruction. The primary objective was to compare the mechanical properties of grafts used for ACL reconstruction during a tensile failure test. The secondary objective was to evaluate the effect of uniform suturing on graft strength. Fifteen pairs of knees were used. The mechanical properties of five types of ACL grafts were evaluated: patellar tendon (PT), sutured patellar tendon (sPT), both hamstring tendons (GST4), quadrupled semitendinosus (ST4), and quadrupled gracilis (G4). Validated methods were used to perform the tensile tests to failure and to record the results. Student's t‐test was used to compare the various samples. The maximum load to failure was 630.8N (± 239.1) for the ST4, 473.5N (± 176.9) for the GST4, 413.3N (± 120.4) for the sPT, and 416.4N (± 187.7) for the G4 construct. Only the ST4 had a significantly higher failure load than the other grafts. The sPT had a higher failure load than the PT. The ST4 construct had the highest maximum load to failure of all the ACL graft types in the testing performed here. Uniform suturing of the grafts improved their ability to withstand tensile loading. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1188–1196, 2015.