Autologous patellar tendon and quadrupled hamstring grafts in anterior cruciate ligament reconstruction: a prospective randomized multicenter review of different fixation methods

ACL reconstruction with bone patellar tendon bone (BPTB) grafts has been shown to produce dependable results. Recently, reconstructions with double-looped semitendinosus gracilis (DLSG) grafts have become common. The prevailing opinion is that ACL reconstruction with patellar tendon graft produces a more stable knee with more anterior knee pain than DLSG grafts, while the functional results and knee scores are similar. The present study evaluates BPTB grafts fixed with metallic interference screws and DLSG grafts fixed with Bone Mulch Screw on the femur and WasherLoc fixation on the tibia. All else being the same, there is no difference in the outcome between the two grafts and fixation methods. This is a prospective randomized multicenter study. A total of 115 patients with isolated ACL ruptures were randomized to either reconstruction with BPTB grafts fixed with metal interference screws (58 patients) or DLSG grafts (57 patients) fixed with Bone Mulch Screws and WasherLoc Screws. Follow-up was at one and two years; the latter by an independent observer. At two years, one ACL revision had been performed in each group. Eight patients in the DLSG group and one in the BPTB group underwent meniscus surgery in the follow-up period (P = 0.014). Mean Lysholm score at the two year follow-up was 91 (SD ± 10.3) in the DLSG group and also 91 (SD ± 10.2) in the BPTB group. Mean KT-1000 at two years was 1.5 mm in the BPTB group and 1.8 mm in the DLSG group (n.s.). At two years, four patients in the BPTB group and three in the DLSG group had a Lachman test grade 2 or 3 (n.s.). More patients in the BPTB group had pain at the lower pole of the patella (P = 0.04). Peak flexion torque and total flexion work were lower in the DLSG group at one year (P = 0.003 and P = 0.000) and total flexion work also at two years (P = 0.05). BPTB ACL reconstruction fixed with interference screws and DLSG fixed with Bone Mulch Screws on the femur and WasherLoc Screws on the tibia produce satisfactory and nearly identical outcomes. Among our patients in the DLSG group, flexion strength was lower, and more patients underwent meniscus surgery in the follow-up period. The BPTB group has more anterior knee pain.     

Evaluation of ACL mid-substance cross-sectional area for reconstructed autograft selection

Purpose

The purpose of this study was to compare the size of the native ACL mid-substance cross-sectional area and the size of commonly used autografts. Hypothesis of this study was that the reconstructed graft size with autografts would be smaller than the native ACL size.

Methods

Twelve non-paired human cadaver knees were used. The ACL was carefully dissected, and the mid-substance of the ACL was cross-sectioned parallel to the articular surface of the femoral posterior condyles at 90 degrees of knee flexion. The size of the cross-sectional area of the ACL, and the femoral and tibial footprints were measured using Image J software (National Institute of Health). The semitendinosus tendon (ST) and the gracilis (G) tendon were harvested and prepared for ACL grafts. Simulating an ST graft, the ST was cut in half. The bigger half was regarded as the antero-medial (AM) bundle, and the remaining half was regarded as the postero-lateral (PL) bundle. Simulating an ST-G graft, the bigger half of the ST and G were regarded as the AM bundle, and the smaller half of the ST was regarded as the PL bundle. Each graft diameter was measured, and the graft area was calculated. Simulating a rectangular bone-patella tendon-bone (BPTB) graft, a 10-mm-wide BPTB graft was harvested and the area calculated.

Results

The sizes of the ACL mid-substance cross-sectional area, femoral and tibial ACL footprint were 46.9 ± 18.3, 60.1 ± 16.9 and 123.5 ± 12.5 mm², respectively. The average areas of the ST, ST-G, and BPTB grafts were 52.0 ± 3.8, 64.4 ± 6.2, and 40.8 ± 6.7 mm², respectively. The ST and BPTB grafts showed no significant difference in graft size when compared with the ACL cross-sectional area.

Conclusion

ST and BPTB autografts were able to reproduce the native size of the ACL mid-substance cross-sectional area. The ST-G graft was significantly larger than the ACL cross-sectional area. For clinical relevance, ST and BPTB grafts are recommended in order to reproduce the native size of the ACL in anatomical ACL reconstruction with autograft.     

Arthroscopic single-bundle ACL reconstruction with modified double-layer bone-patellar tendon-bone allograft

Purpose

The objective of present study was to introduce a modified double-layer bone-patellar tendon-bone (BPTB) allograft for arthroscopic single-bundle ACL reconstruction and investigate the clinical outcomes.

Methods

From 2007 to 2009, a total of 136 patients underwent arthroscopic single-bundle ACL reconstructions with BPTB allograft. Of which, 66 patients were with double-layer BPTB allograft (Group 1), and 70 patients were with conventional BPTB allograft (Group 2). Clinical outcomes including Lachman and pivot-shift tests, KT-1000 arthrometer measurements, and Lysholm and Tegner activity scores were compared between the two groups at a 2-year minimum follow-up.

Results

Forty-six patients in each group were at a two-year minimum follow-up. The mean side-to-side difference on the KT-1000 arthrometer was 1.2 ± 1.2 mm for group 1 and 2.1 ± 1.9 mm for group 2, with significant difference between the two groups (p = 0.017). The knee function was significantly better for group 1 than for group 2, because the mean Lysholm score was 94.2 ± 4.8 points versus 86.6 ± 7.1 points (p = 0.000), and the median Tegner score was 8 (range 5–10) points versus 6 (range 4–10) points (p = 0.001).

Conclusions

On the basis of the KT-1000 arthrometer evaluation and clinical measures, single-bundle ACL reconstruction with double-layer BPTB allograft achieves significantly lesser anterior laxity and better knee function than a single-layer allograft reconstruction.

Level of evidence

Therapeutic, retrospective comparative study, Level III.     

Size comparison of ACL footprint and reconstructed auto graft

Purpose

The purpose of this study was to compare the size of native anterior cruciate ligament (ACL) footprints and the size of commonly used auto grafts. The hypothesis was that the reconstructed graft size with auto grafts might be smaller than the native ACL footprint.

Methods

Fourteen non-paired human cadaver knees were used. The semitendinosus tendon (ST) and the gracilis (G) tendon were harvested and prepared for ACL grafts. Simulating an ST graft, the ST was cut in half. The bigger half was regarded as the antero-medial (AM) bundle, and the remaining half was regarded as the postero-lateral (PL) bundle. Simulating an ST–G graft, the bigger half of the ST and G were regarded as the AM bundle, and the smaller half of the ST was regarded as the PL bundle. Each graft diameter was measured, and the graft area was calculated. Simulating a rectangular bone-patella tendon-bone (BPTB) graft, a 10-mm wide BPTB graft was harvested and the area calculated. The ACL was carefully dissected, and the size of the femoral and tibial footprints was measured using Image J software (National Institution of Health).

Results

The average areas of the ST, ST–G, and BPTB graft were 52.3 ± 7.3, 64.4 ± 9.2, and 32.7 ± 6.5 mm², respectively. The sizes of the native femoral and tibial ACL footprints were 85.4 ± 26.3 and 145.4 ± 39.8 mm², respectively. Only the ST–G graft showed no significant difference in graft size when compared with the femoral ACL footprint.

Conclusion

Only the ST–G auto graft was able to reproduce the native size of the ACL footprint on the femoral side. None of the auto grafts could reproduce the size of the tibial ACL footprint. For clinical relevance, ST–G graft is recommended in order to reproduce the native size of the ACL in anatomical ACL reconstruction with auto graft.     

Effect of muscle preserved on tendon graft on intra-articular healing in anterior cruciate ligament reconstruction

Purpose

The aim of this study was to determine the impact on intra-articular healing of muscle tissue retained on tendon grafts used for anterior cruciate ligament (ACL) reconstruction.

Methods

In an animal study on 40 New Zealand rabbits, a semi-tendon/semi-muscle graft (SSG) and a total tendon graft (TTG) were individually harvested from the Achilles tendons in each animal. After transecting the ACLs in both knees of each rabbit, SSG and TTG were randomly used on bilateral sides of the knee for ACL reconstruction. After 2, 4, and 8 weeks, functional scoring, gross observations, and histological evaluations of the repaired knees were performed (each time point; n = 10). Biomechanical testing was conducted on remaining animals at 8 weeks (n = 10).

Results

At 2, 4, and 8 weeks after surgery, there were no statistically significant differences in functional scores between the SSG group and TTG group (n.s.). As healing progressed, skeletal muscle on the SSG was gradually absorbed with a corresponding decrease in graft diameter, compared to TTG, at each time point (P < 0.001). However, healing and incorporation of the intra-articular graft in the SSG were more apparent than those in the TTG, based on histology. The vascularity and cellularity in the center of the sample were significantly greater in the SSG group than the TTG group at all the time points (P < 0.01). At 8 weeks, the SSG group’s ultimate failure load, yield load, and elongation at failure were significantly less than for the TTG group (P < 0.01). There were no significant differences in stiffness between the two groups with biomechanical testing (n.s.).

Conclusion

Results of this study indicate that muscle left on tendon grafts promotes intra-articular healing and remodeling of the graft in a rabbit model. However, excessive amounts of retained skeletal muscle weaken tendon graft’s strength for ACL reconstruction. Preserving small amounts of muscle on tendon grafts is feasible for improving the biological success of ACL reconstruction in humans.     

Fractionation of high-dose electron beam irradiation of BPTB grafts provides significantly improved viscoelastic and structural properties compared to standard gamma irradiation

Purpose

Irradiation >30 kGy is required to achieve sterility against bacterial and viral pathogens in ACL allograft sterilization. However, doses >20 kGy substantially reduce the structural properties of soft-tissue grafts. Fractionation of irradiation doses is a standard procedure in oncology to reduce tissue damage but has not been applied in tissue graft sterilization.

Methods

Forty-four human 10-mm wide bone-patellar-tendon-bone grafts were randomized into four groups of sterilization with (1) 34 kGy of ebeam (2) 34 kGy gamma (3) 34 kGy fractionated ebeam, and (4) non sterilized controls. Graft´s biomechanical properties were evaluated at time zero. Biomechanical properties were analyzed during cyclic and load-to-failure testing.

Results

Fractionation of ebeam irradiation resulted in significantly higher failure loads (1,327 ± 305) than with one-time ebeam irradiation (1,024 ± 204; P = 0.008). Compared to gamma irradiation, significantly lower strain (2.9 ± 1.5 vs. 4.6 ± 2.0; P = 0.008) and smaller cyclic elongation response (0.3 ± 0.2 vs. 0.6 ± 0.4; P = 0.05), as well as higher failure loads (1,327 ± 305 vs. 827 ± 209; P = 0.001), were found. Compared to non-irradiated BPTB grafts, no significant differences were found for any of the biomechanical parameters. Non-irradiated controls had significantly lower cyclic elongation response and higher failure loads than ebeam and gamma irradiation.

Conclusions

In this study, it was found that fractionation of high-dose electron beam irradiation facilitated a significant improvement of viscoelastic and structural properties of BPTB grafts compared to ebeam and gamma irradiation alone, while maintaining levels of non-irradiated controls. Therefore, this technique might pose an important alternative to common methods for sterilization of soft-tissue allografts.     

Iliotibial band autograft versus bone-patella-tendon-bone autograft,a possible alternative for ACL reconstruction: a 15-year prospective randomized controlled trial

Purpose

The long-term results after using the iliotibial band autograft (ITB) in anterior cruciate ligament (ACL) reconstruction are not fully known. If equal in quality to conventional methods, the ITB graft could be a useful alternative as a primary graft, in revision surgery or multi-ligament reconstruction. The purpose is to assess whether the ITB autograft is a long-term reliable alternative to the bone-patella-tendon-bone (BPTB) autograft, using a prospective randomized controlled trial design.

Methods

From 1995 to 1996, sixty patients scheduled for primary ACL reconstruction were included in a prospective randomized controlled trial. Three senior knee surgeons, experienced in both types of ACL surgery, performed all the operations. A standardized and supervised rehabilitation programme was used for both groups for 6 months. Thirty patients received the ITB reconstruction, and 30 received the BPTB reconstruction. Forty-nine participated at follow-up in 2010 (82 %). Primary outcome was the failure rate after ACL reconstruction. Secondary outcomes were knee injury osteoarthritis outcome score (KOOS) [pain, symptoms, Sport/Rec, quality of life (QOL), daily living function], Tegner activity scale, anterior knee pain-score, Lysholm score, Rolimeter laxity, extension deficit, single hop and crossover hop for distance.

Results

At 15-year follow-up, no significant difference existed between the groups. Graft failure occurred in 4 ITB subjects (16 %) and 3 BPTB subjects (13 %). KOOS (Sport/Rec) for the ITB group was 75 and 73 for the BPTB group. The KOOS (QOL) was 72 and 68 for the ITB group and BPTB group, respectively.

Conclusion

Similar graft failure rates and KOOS were found when comparing ITB- and BPTB-operated individuals, at 15-year follow-up. The ITB graft had equal long-term clinical results compared to the BPTB graft and is recommended as a reliable alternative autograft for ACL reconstruction.

Level of evidence

Therapeutic studies, Level I.     

Femoral fixation of hamstring tendon grafts in ACL reconstructions: the 2-year follow-up results of a prospective randomized controlled study

Purpose

Hamstring tendon grafts are commonly used in anterior cruciate ligament (ACL) reconstructions. A number of fixation devices are available; however, several have limited clinical support. To our knowledge, no randomized controlled study comparing the EZLoc and the Bone Mulch Screw for femoral fixation in ACL reconstruction exists. Therefore, the purpose of this study was to compare the results following the use of these two femoral fixation devices. Time in surgery for the two methods was also to be compared.

Methods

A total of 110 patients between 18 and 45 years old at two orthopaedic departments, A (n = 55) and B (n = 55), were randomized to ACL reconstruction with femoral fixation of the hamstring graft with either the EZLoc or the Bone Mulch Screw. Surgical time was measured for each group. The patients were evaluated after 6 weeks and 3, 6, 12 and 24 months. The clinical examination included range of motion, evaluation of intraarticular swelling, tenderness at the lateral femoral condyle, the Lachman test, the Pivot shift test and the KT-1000 arthrometer. In addition, the visual analogue scale score for pain, the Tegner activity score, the Lysholm functional score and the knee injury and osteoarthritis outcome score were recorded. Knee extension and flexion muscle strength were also measured with a Biodex.

Results

There were no significant differences in any of the parameters mentioned above at the 2-year follow-up evaluation. Three patients in each group underwent revision ACL reconstruction during the study. More than 95 % of the knees in both groups were found to be stable. Good to excellent results were found for all selected knee scores in both groups. There were no statistically significant differences between the two groups in any of the muscle strength parameters. Time in surgery was statistically significantly shorter in the EZLoc group compared with the Bone Mulch group.

Conclusion

There were no statistically significant differences in clinical findings, knee scores or in muscle strength between the EZLoc group and the Bone Mulch group at the 2-year follow-up evaluation. Time in surgery was statistically significantly shorter for patients undergoing ACL reconstruction with hamstring grafts when the EZLoc femoral fixation device was used.

Level of evidence

II.     

Anatomic single- versus double-bundle ACL reconstruction: a meta-analysis

Purpose

To determine whether anatomic double-bundle anterior cruciate ligament (ACL) reconstruction compared to anatomic single-bundle ACL reconstruction more effectively restored antero–posterior (A–P) laxity, rotatory laxity and reduced frequency of graft rupture. Our hypothesis was that anatomic double-bundle ACL reconstruction results in superior rotational knee laxity and fewer graft ruptures due to its double-bundle tension pattern, compared with anatomic single-bundle ACL reconstruction.

Methods

An electronic search was performed using the PubMed, EMBASE and Cochrane Library databases. All therapeutic trials written in English reporting knee kinematic outcomes and graft rupture rates of primary anatomic double- versus single-bundle ACL reconstruction were included. Only clinical studies of levels I–II evidence were included. Data regarding kinematic tests were extracted and included pivot-shift test, Lachman test, anterior drawer test, KT-1000 measurements, A–P laxity measures using navigation and total internal–external (IRER) laxity measured using navigation, as well as graft failure frequency.

Results

A total of 7,154 studies were identified of which 15 papers (8 randomized controlled trials and 7 prospective cohort studies, n = 970 patients) met the eligibility criteria. Anatomic ACL double-bundle reconstruction demonstrated less anterior laxity using KT-1000 arthrometer with a standard mean difference (SMD) = 0.36 (95 % CI 0.214–0.513, p < 0.001) and less A–P laxity measured with navigation (SMD = 0.29 95 % CI 0.01–0.565, p = 0.042). Anatomic double-bundle ACL reconstruction did not lead to significant improvements in pivot-shift test, Lachman test, anterior drawer test, total IRER or graft failure rates compared to anatomic single-bundle ACL reconstruction.

Conclusion

Anatomic double-bundle ACL reconstruction is superior to anatomic single-bundle reconstruction in terms of restoration of knee kinematics, primarily A–P laxity. Whether these improvements of laxity result in long-term improvement of clinical meaningful outcomes remains uncertain.

Level of evidence

II.     

Commonly used ACL autograft areas do not correlate with the size of the ACL footprint or the femoral condyle

Purpose

The purpose of this study was to reveal the correlation between the size of the native anterior cruciate ligament (ACL) footprint and the area of commonly used autografts using cadaveric knees.

Methods

Twenty-Four non-paired human cadaver knees were used. The size of the femoral and tibial ACL footprints, length of Blumensaat’s line, and the height and area of the lateral wall of the femoral intercondylar notch were photographed and measured with Image J software (National Institution of Health). Simulating an semitendinosus tendon (ST) graft, the ST was cut in half. The bigger half was regarded as the antero-medial (AM) bundle, and the remaining half was regarded as the postero-lateral (PL) bundle. Simulating an semitendinosus and gracilis (ST–G) graft, the bigger half of the ST and G was regarded as the AM bundle, and the smaller half of the ST was regarded as the PL bundle. Each graft diameter was measured, and the graft area was calculated. Simulating a bone–patella tendon–bone (BPTB) graft, a 10-mm wide BPTB graft was harvested and the area calculated.

Results

The sizes of the native femoral and tibial ACL footprints were 72.3 ± 24.4 and 134.1 ± 32.4 mm², respectively. The length of Blumensaat’s line, and the height and area of the lateral wall of the femoral intercondylar notch were 29.5 ± 2.5 mm, 17.7 ± 2.3 mm, and 400.9 ± 62.6 mm², respectively. The average areas of the ST, ST–G, and BPTB graft were 52.7 ± 6.3, 64.7 ± 7.6, and 37.1 ± 7.5 mm². Both the height and the area of the lateral wall of the femoral intercondylar notch were significantly correlated with the femoral size of the ACL footprint (p = 0.007 and 0.008, respectively). However, no significant correlation was observed between ACL footprint size and autograft size. No significant correlation was observed between autograft size and the size of the lateral wall of the femoral intercondylar notch.

Conclusion

In ACL reconstruction, if the reconstructed ACL size is determined by the harvested autograft size alone, native ACL size and anatomy are unlikely to be reproduced.     

The effect of anterior cruciate ligament graft orientation on rotational knee kinematics

Purpose

To determine whether coronal graft orientation and tunnel placement for single-bundle anterior cruciate ligament (ACL) reconstruction is associated with tibial rotation excursion during functional activities.

Methods

Eighty-four patients who had undergone ACL reconstruction over a ten-year time span had tibial rotation measured during level walking, using a three-dimensional motion analysis system. Fifty-two patients also had measures taken during the more dynamic task of single-limb landing. During the 10-year period, the position of the graft was deliberately changed from a vertical to more horizontal orientation in the coronal plane. Post-operative radiographs were analysed for the coronal graft orientation and femoral and tibial tunnel positions. Radiographic measurements of graft orientation and tunnel position were then correlated with the amount of tibial rotational excursion recorded during the walking and landing tasks.

Results

For the single-limb landing task, a significant positive correlation was observed between the coronal graft angle and rotational excursion (R = 0.35, R ²  = 0.12, p = 0.01). This indicated greater rotational excursion was associated with vertical graft orientation, but only explained 12 % of the variance. No correlations were found between coronal graft angle and tibial rotation during level walking.

Conclusions

These findings support the notion that ACL graft orientation may play a role in rotational kinematics of the ACL-reconstructed knee, particularly during higher impact activities.

Level of evidence

IV.     

No infections in 1300 anterior cruciate ligament reconstructions with vancomycin pre-soaking of hamstring grafts

Purpose

To investigate the pre-soaking of hamstring grafts in topical vancomycin, in addition to IV prophylaxis, during anterior cruciate ligament (ACL) reconstruction to reduce the incidence of post-operative infection, and to describe an evidence-based diagnostic and treatment algorithm to facilitate early diagnosis and appropriate management of possible knee sepsis post-operatively after ACL reconstruction.

Methods

This study is a controlled observational series comprising of 1585 individuals who underwent ACL reconstruction over a 13-year period. All surgeries were performed by a single surgeon at the same hospital. Group 1 consisted of 285 patients who received pre-operative IV antibiotics without topical graft pre-soaking. Group 2 consisted of 1300 individuals who received IV antibiotics and graft pre-soaking in a vancomycin solution of 5 mg/mL.

Results

In group 1, a total of four patients suffered a post-operative joint infection (1.4 %). Three out of the four were culture positive for Staphylococcus species. The fourth was culture negative but was managed as an acute infection. Group 2 suffered no post-operative infections (0 %). Statistical analysis of the vancomycin pre-soak with IV antibiotics group, compared with IV antibiotics-alone group, revealed a significantly reduced post-operative infection rate using a Fisher’s exact test (P = 0.0011) and Chi-square test with Yates’ correction (P = 0.0003).

Conclusions

Pre-soaking of hamstrings grafts with topical vancomycin reduced the rate of post-operative infection when compared to IV antibiotics alone. This technique should be utilised by surgeons to reduce the overall incidence of knee sepsis post-ACL reconstruction.

Level of evidence

III.

     

Effect of graft tensioning on mechanical restoration in a rat model of anterior cruciate ligament reconstruction using free tendon graft

Purpose

Initial graft tensioning is important in anterior cruciate ligament reconstruction (ACLR), but its effect on graft healing is still not clear. Since all previous animal studies on graft tensioning used bone–patellar tendon–bone, this study aimed to investigate the effect of initial graft tensioning on ACLR using tendon graft.

Methods

Fifty-five Sprague–Dawley rats underwent ACLR using flexor digitorum longus tendon graft. A constant force of 2 or 4 N was applied during graft fixation. At 0, 2, and 6 weeks, knee samples were harvested (n = 6) for static knee laxity test and graft pull-out test. Histological examination was performed at 2 and 6 weeks post-injury (n = 4).

Results

At time zero, knee laxity was restored by ACLR with 2 or 4 N tensioning as compared to ACL-deficient group (p < 0.001), and the 4 N group exhibited a better restoration as compared to 2 N group (p = 0.031). At week 2 post-operation, the 4 N group still exhibited a better restoration in knee laxity (p = 0.001) and knee stiffness (p = 0.002) than the 2 N group; the graft pull-out force (p = 0.032) and stiffness (p = 0.010) were also higher. At week 6 post-operation, there was no significant difference between the 2 and 4 N group in knee laxity and graft pull-out strength. Histological examination showed that the beneficial effect of higher initial graft tension may be contributed by maintenance of graft integrity at mid-substance and reduction in adverse peri-graft bone changes in the femoral tunnel region.

Conclusions

A higher initial graft tension favours the restoration of knee laxity and promotes graft healing in ACLR using free tendon graft in the rat model.     

Anatomic ACL reconstruction produces greater graft length change during knee range-of-motion than transtibial technique

Purpose

Because distance between the knee ACL femoral and tibial footprint centrums changes during knee range-of-motion, surgeons must understand the effect of ACL socket position on graft length, in order to avoid graft rupture which may occur when tensioning and fixation is performed at the incorrect knee flexion angle. The purpose of this study is to evaluate change in intra-articular length of a reconstructed ACL during knee range-of-motion comparing anatomic versus transtibial techniques.

Methods

After power analysis, seven matched pair cadaveric knees were tested. The ACL was debrided, and femoral and tibial footprint centrums for anatomic versus transtibial techniques were identified and marked. A suture anchor was placed at the femoral centrum and a custom, cannulated suture-centring device at the tibial centrum, and excursion of the suture, representing length change of an ACL graft during knee range-of-motion, was measured in millimeters and recorded using a digital transducer.

Results

Mean increase in length as the knee was ranged 120°–0° (full extension) was 4.5 mm (±2.0 mm) for transtibial versus 6.7 mm (±0.9 mm) for anatomic ACL technique. A significant difference in length change occurs during knee range-of-motion both within groups and between the two groups.

Conclusions

Change in length of the ACL intra-articular distance during knee range-of-motion is greater for anatomic socket position compared to transtibial position. Surgeons performing anatomic single-bundle ACL reconstruction may tension and fix grafts with the knee in full extension to minimize risk of graft stretch or rupture or knee capture during full extension. This technique may also result in knee anterior–posterior laxity in knee flexion.     

Factors predicting hamstring tendon autograft diameters and resulting failure rates after anterior cruciate ligament reconstruction

Purpose

The purposes of this study are to confirm factors that affect the diameter of hamstring tendon autograft and to compare failure rates between the factors after anterior cruciate ligament (ACL) reconstruction.

Methods

A total of 296 patients that underwent reconstruction using hamstring tendon autograft at our clinics for ACL injury between September 2005 and June 2008 were enrolled for this study. The diameters of gracilis and semitendinosus tendons (harvested from the affected knee) and four-strand graft tendon made by folding the gracilis and semitendinosus tendons in two layers were measured. Before operating, we recorded the age, height, weight, Body Mass Index (BMI), gender and athlete versus non-athlete identity of the subjects and checked their correlations with graft diameters. Patients that recorded a grade C or D on the International Knee Documentation Committee Knee Examination Form, as well as patients that underwent revision, were defined as failures and analysed by related factors.

Results

The mean diameter was 1.5 mm ± 0.2 for gracilis tendon, 2.2 mm ± 0.3 for semitendinosus tendon and 7.2 mm ± 0.7 for graft tendon. Except for age, factors including height, weight, BMI, gender and athlete versus non-athlete identity were found to be significantly related to graft diameter. Correlation was strongest with height (p < 0.001). With respect to failure rates after ACL reconstruction, patients with a graft diameter of 8.0 mm or more demonstrated statistically better results than patients with a diameter of below 8.0 mm (p = 0.043). However, failure rates did not differ significantly with respect to other factors.

Conclusions

The diameter of hamstring tendon autograft may be different depending on height, weight, BMI and gender of the patient, as well as whether or not the patient is an athlete. Although we did not find statistically significant differences in failure rates after ACL reconstruction, this study demonstrated relatively better results in patients with a graft diameter of 8.0 mm or more.

Level of evidence

Case series, Level IV.     

Long-term results of a randomized study on anterior cruciate ligament reconstruction with or without a synthetic degradable augmentation device to support the autograft

Purpose

The aim was to compare the outcome of anterior cruciate ligament (ACL) reconstruction with bone-patellar tendon-bone (BPTB) autograft, with and without a poly(urethane urea) augmentation device.

Methods

Patients were randomized to BPTB reconstruction with a synthetic degradable augmentation device (n = 96) or without augmentation (n = 105). Follow-ups were made during 4 years after surgical treatment with the KT1000? arthrometer for objective evaluation of sagittal stability. The Tegner scoring system for assessment of physical activity level and the Knee injury Osteoarthritis Outcome Score (KOOS) for assessment of knee-specific health were evaluated after 4 and 12 years.

Results

KT1000? tests showed a significant decrease in mean manual maximum side-to-side difference after 4 years in both patients with and those without augmentation, without any statistical difference between the groups (n.s.). Pre-injury, 76 and 80 % of the patients, respectively, reported Tegner level 7–10. Pre-surgery, the corresponding figures were 6 and 5 %, and at 4 years, 33 and 30 %. Twelve years after ACL reconstruction, both groups had significantly higher KOOS scores in function in sports and recreational activities (p < 0.001) and knee-related quality of life (p < 0.001) compared to before surgical treatment. In 10 patients, the augmentation device was removed, in six of these because of insufficient screw fixation to femur and in four due to swelling/hydrops.

Conclusion

This study showed no significant difference in clinical outcome with use of an additional synthetic augmentation device in a single-bundle BPTB ACL reconstruction compared with non-augmentation, in short, intermediate, or long-term perspective.

Level of evidence

Therapeutic study, Level I.     

Calcium phosphate-hybridized tendon grafts reduce femoral bone tunnel enlargement in anatomic single-bundle ACL reconstruction

Purpose

This study aimed to clarify the effect of calcium phosphate (CaP)-hybridized tendon grafting versus unhybridized tendon grafting on the morphological changes to the bone tunnels at the aperture 1 year after anatomic single-bundle anterior cruciate ligament (ACL) reconstruction.

Methods

Seventy-three patients were randomized to undergo the CaP (n = 37) or the conventional method (n = 36). All patients underwent computed tomography (CT) evaluation 1 week and 1 year post-operatively. The femoral and tibial tunnels at the aperture were evaluated on reconstructed 3D CT images. Changes in the cross-sectional area (CSA) and diameters of the femur and the tibia, and the translation rate of the tunnel walls and the morphological changes of both tunnels were assessed.

Results

There was a significant reduction in the increase in the CSA and the anterior–posterior and proximal–distal tunnel diameters on the femoral side in the CaP group as compared with the conventional group. On the femoral side, the translation rate of the posterior wall was significantly larger in the CaP group than in the conventional group, whereas the translation rate of the distal wall was significantly smaller in the CaP group than in the conventional group.

Conclusions

As compared with the conventional method, the CaP-hybridized tendon graft reduced bone tunnel enlargement on the femoral side 1 year after anatomic single-bundle ACL reconstruction due to an anterior shift of the posterior wall and reduced distal shift in the femoral bone tunnel. Clinically, the CaP-hybridized tendon grafts can prevent femoral bone tunnel enlargement in anatomic single-bundle ACL reconstruction.

Level of evidence

I.

     

The effect of notchplasty in anterior cruciate ligament reconstruction: a biomechanical study in the porcine knee

Introduction

Notchplasty is frequently performed by many orthopaedic surgeons during anterior cruciate ligament (ACL) reconstruction. The effect of notchplasty on tunnel placement and knee biomechanics with ACL reconstruction is not known.

Methods

Twelve (n = 12) porcine knees were tested using a robotic testing system. Four knee states were compared: (1) intact ACL, (2) ACL-deficient, (3) anatomic single bundle (SB) ACL reconstruction and (4) anatomic SB ACL reconstruction with a 5-mm notchplasty. The graft was fixed at 60° of flexion (full extension of porcine knee is 30°) with an 80-N tension. The knees were subjected to two loading conditions: an 89-N anterior tibial load (ATT) and 4 Nm internal (IR) and external tibial (ER) rotational torques. The kinematics and in situ force obtained from the different knee conditions were compared.

Results

There were no significant differences between pre- and post-notchplasty in the ER at 30° and 60° of knee flexion (n.s.). However, a significant difference was found between pre- and post-notchplasty in ATT at 30° and 60° of flexion (p < 0.05). The in situ force in the anatomic SB reconstruction with notchplasty was significant lower than the intact and anatomic reconstructed ACL pre-notchplasty at 30°, 60° and 90° of knee flexion (p < 0.05). In response to the IR tibial torque, there were significant differences between pre- and post-notchplasty in IR at 60° (p < 0.05) of knee flexion.

Conclusion

Notchplasty had greater effect on anterior stability than rotational stability. This change in knee kinematics could be detrimental to a healing bone graft, ligamentization and could lead to failure of the reconstruction in early post-operative period.     

Intra-articular remodelling of hamstring tendon grafts after anterior cruciate ligament reconstruction

Purpose

A summary is provided on the existing knowledge about the specific healing phases of the intra-articular hamstring tendon graft used for ACL reconstruction. Differences between human and animal in vivo studies are explained, and implications for the postoperative time period are laid out.

Methods

A systematic review of the existing literature was performed on the topic of tendon remodelling of hamstring grafts in ACL reconstruction using Medline database. Publications between 1982 and 2012 were included. Special focus was directed on in vivo human and animal studies analysing intra-articular free tendon graft remodelling.

Results

Animal and human in vitro and vivo researches have demonstrated three characteristic stages of graft healing after ACL reconstruction: an early graft healing phase with central graft necrosis and hypocellularity and no detectable revascularization of the graft tissue, followed by a phase of proliferation, the time of most intensive remodelling and revascularization and finally, a ligamentization phase with characteristic restructuring of the graft towards the properties of the intact ACL. However, a full restoration of either the biological or biomechanical properties of the intact ACL is not achieved.

Conclusion

Significant knowledge on human cruciate ligament remodelling has been added in the understanding of the processes during the course of graft healing. Most importantly, the remodelling process in humans is prolonged compared to animal studies. While today´s rehabilitation protocols are often extrapolated from findings of animal in vivo healing studies, current findings of human in vivo healing studies might require new post-operative regimens following hamstring ACL reconstruction.     

Graft size after anterior cruciate ligament reconstruction

Purpose

The native anterior cruciate ligament (ACL) is composed of two distinct bundles, the anteromedial (AM) and posterolateral (PL), and both have been shown to be reliably measured on magnetic resonance imaging (MRI). The purpose of this study was to measure the size of the AM and PL bundles after ACL double-bundle reconstructions on MRI and compare this to the relative graft size at the time of surgery.

Methods

Between January 2007 and April 2010, 85 knees were identified after allograft double-bundle ACL reconstruction with post-operative MRI (1.5 T) and met inclusion criteria. On standard sagittal, coronal and oblique coronal MRIs, the AM and PL bundles were delineated and the midsubstance width of the ACL graft was measured. The images were independently measured in a blinded fashion by two observers. Linear and curvilinear regression analysis was used to analyse the relationship between graft size and time after reconstruction.

Results

The mean age of the patients was 24.6 years (SD 10.4). Mean time from surgery to post-operative MRI was 271.5 days (SD 183.4). The mean percentage of the original size of the AM bundle was 86.9 % (SD 9.9) and of the PL bundle was 88.6 % (SD 9.9). There was no correlation between the relative size of the AM graft and the time from surgery (r = 0.3, n.s.) and no significant relationship for the PL graft (r = 0.1, n.s).

Conclusion

On average, there was no graft enlargement of the AM and PL grafts 275.1 days after allograft ACL double-bundle reconstruction, as the mean relative graft size was less than 100 % on MRI. This study suggests that surgeons, who use allografts, should measure the ACL and replace it with a similar size, as there is a low risk of hypertrophy of the graft within one year post-operative.

Level of evidence

IV.