Revision of anterior cruciate ligament reconstruction with allografts in patients younger than 40 years old: a 2 to 4 year results

Purpose

The purpose of this study is first to report the outcomes, at 4 years follow-up, in revision ACL surgery using allografts in patients younger than 40 years old, and then compared soft tissue allografts to bone tendon allografts.

Methods

This retrospective study included 47 patients who underwent ACL revision surgery with fresh-frozen allografts. Patellar tendon allograft or tibialis anterior allograft was used. Twenty-seven patients undergoing ACL revision with patellar tendon allograft were compared retrospectively with twenty-two patients undergoing the same procedure with soft tissue tibialis anterior allograft. Lysholm, IKDC, and KT-1000 values were obtained preoperatively and postoperatively.

Results

The average patient follow-up was 4.6 years (±2.5). The mean age at time of the revision was 34 years old (±6.3). Overall, patients reported the overall condition of their knee as excellent or good in 85 % of the patients (10 excellent, 33 good). Based on their experience, 85 % would have the surgery again if they had the same problem in the other knee. Both subgroups experienced significant improvement in Lysholm, IKDC, and KT-1000 values, with no difference found between groups at final follow-up.

Conclusion

Revision ACL with allografts has excellent and good results in 85 % of patients younger than 40 years old. No statistical difference was seen between soft tissue (tibialis anterior) and patellar tendon allograft.

Level of evidence

IV.     

Comparison of Achilles and tibialis anterior tendon allografts after anterior cruciate ligament reconstruction

Purpose

The purpose of this study was to compare the outcomes after anterior cruciate ligament (ACL) reconstruction using Achilles tendon allografts and tibialis anterior (TA) tendon allografts with respect to objective knee testing measures, second-look arthroscopy and femoral tunnel enlargement.

Methods

A total of 131 patients who underwent ACL reconstruction between 2000 and 2006 were retrospectively reviewed. Achilles tendon allografts were used in 81 patients (group I). These patients were compared with 50 patients in whom TA tendon allografts were used (group II). The two groups were assessed using International Knee Documentation Committee (IKDC), Lysholm and Tegner activity scores, as well as KT-2000 testing. Second-look arthroscopic findings were evaluated. Cross-sectional area (CSA) perpendicular to the long axis of the femoral tunnel was also calculated digitally using magnetic resonance imaging.

Results

No significant differences were observed between the two groups with respect to IKDC, Lysholm or Tegner activity scores or the results of laxity testing with arthrometry. Synovial coverage of more than 50 % was found in 71.1 % cases in group I and 75 % cases in group II. Mean CSA enlargement of 15 % (group I) and 38 % (group II) was detected (p = 0.017).

Conclusions

The clinical results associated with Achilles and TA tendons were not significantly different. The laxity evaluation and second-look arthroscopy demonstrated no significant differences between group I and group II. However, Achilles tendon-bone plugs for femoral tunnel fixation reduced femoral tunnel enlargement compared to the TA allograft. Achilles tendon allografts for ACL reconstruction could be a reasonable option in selected patients.

Level of evidence

Retrospective case series, Level IV.     

Allografts in the treatment of anterior cruciate ligament injuries

Symptomatic knee instability is a common complaint among athletic individuals after a torn anterior cruciate ligament (ACL) of the knee. Allograft ACL reconstruction has gained popularity for primary and revision reconstructions. This graft choice has become popular with good intermediate term results combined with decreased operative times, hospital costs, and improved immediate postoperative pain and function. Intermediate follow-up has demonstrated similar results with autograft reconstructions, without the addition of donor site morbidity. Multiple allograft options exist for ACL reconstruction. The most commonly selected grafts include patellar tendon, Achilles tendon, and tibialis allografts. The use of a tibialis allograft provides a stout graft for reconstruction, while minimizing bone tunnel size. Bone-patella-bone allografts provide bone to bone fixation options with flexibility in tunnel selection sizing.     

持续被动活动对兔重建前交叉韧带生物力学特性的影响

目的:采用半腱肌腱重建兔前交叉韧带(ACL),探讨持续被动活动(CPM)对移植物生物力学特性的影响。方法:对30只8月龄雄性新西兰大白兔右侧后肢膝关节行自体双股半腱肌腱移植重建前交叉韧带手术。术后随机分为CPM组和非CPM组两组:CPM组术后第2天开始采用自制兔膝关节CPM器进行持续被动活动,共6周;非CPM组仅笼养。分别于术后第6、12、24周取材,每组每次取5只行生物力学观察。结果:与非CPM组相比,CPM组大部分标本两束融合成一体。从术后6周到24周,所有移植物的最大载荷、最大应力、弹性模量以及这些指标和其对照侧ACL的比值逐渐增加。在术后6、12、24周时,CPM组移植物最大载荷分别为22.72N、79.56N、122.20N,最大应力分别为4.58MPa、13.62MPa、21.79MPa;非CPM组移植物最大载荷分别为16.00N、70.68N、96.20N,最大应力分别为3.07MPa、11.58MPa、17.89MPa。3个时间点两组间上述指标差异均具有统计学意义(P<0.05)。结论:半腱肌腱重建兔前交叉韧带术后早期进行持续被动活动可明显提高移植物的生物力学性能。     

Two to five year results of primary ACL reconstruction using doubled tibialis anterior allograft

The aim of the study was to report the 2–5 year results of primary ACL reconstruction with doubled tibialis anterior allograft. Seventy-three patients who underwent primary ACL reconstruction with doubled tibialis anterior allografts with minimum 2 year follow-up were included in the study. Sixty-four patients were available for follow-up. The median age was 27 years (16–55). There were 33 men and 31 women. The median follow-up was 44.5 months (24–55 months). There were two complications, 1 DVT with subsequent PE, and 1 hardware problem. Four patients had failure of their graft, and six patients required repeat arthroscopy. The median Lysholm score was 88 (range 70–95), and the median Tegner activity score was 6.5 (range 3–10). The median IDKC was 92 (range 73–100). According to the IDKC score, 60% of patients were rated as excellent, 27% as good, and 13% as fair. A total of 25 were able to attend the clinical assessment. On KT-1000, 15 (60%) patients had less than 3 mm side-side difference. Eighteen patients (72%) had no pivot shift. ACL reconstruction with allograft tibialis anterior tendon provided good functional results with a low-failure rate at 2–5 years. There was a statistically significant difference in outcome between men and women, with men performing better on the Lysholm and the IDKC scales.     

三种移植物关节镜下重建前交叉韧带的临床疗效比较

目的比较分析膝关节镜下自体骨-髌腱-骨（B-PT-B）、同种异体跟腱和LARS（1igament advanced reinforce．mentsystem,LARS）人工韧带重建前交叉韧带（anterior cruciate ligament,ACL）的临床疗效差异。方法从2008年2月-2010年11月,对156例膝关节ACL损伤患者行关节镜下ACL重建术,其中自体骨-髌腱-骨（B-PT-B）组39例,同种异体跟腱组53例,LARS人工韧带组64例。通过一般情况、前抽屉试验、Lachman试验、轴移试验、Lysholm、IKDC膝关节评分进行临床疗效评价。结果所有患者随访12-38个月,平均21个月,术后3、6个月各组膝关节Lysholm、IKDC评分,LARS组明显高于其余2组（P〈O．05）。异体跟腱组与自体B-PT-B组相比,差异无统计学意义（P〉0．05）。术后12月及最后随访时,LARS组略高于其余2组,但3组间差异无统计学意义（P〉0．05）。结论在关节镜下应用3种不同移植物重建前交叉韧带的近期疗效均较为满意,LARS组可在术后早期进行膝关节功能活动近期效果优于自体B-PT-B组和异体跟腱组。对于年轻患者．尤其是运动员ACL损伤。LARS人工韧带是一种理想移植材料。     

The tibialis tendon as a valuable anterior cruciate ligament allograft substitute: biomechanical properties

The study evaluates the biomechanical properties of single-strand and single-loop tibialis (anterior and posterior) tendon allografts. A comparison was made with bone-patellar tendon-bone (BPTB) allografts. Sixty-four tendon allografts were evaluated in this study. Sixteen of these were single-strand tibialis anterior (TA) and 16 single-strand tibialis posterior (TP) tendons. Sixteen single-loop TA and TP tendons were also tested. The fourth group was composed of 16 BPTB allografts. The biomechanical properties determined were maximal load, stiffness, cross-sectional area and elongation. The results of this study showed that the maximal load of the single-loop tibialis tendons (1,553 ± 62 N) was greater than of the BPTB (1,139 ± 99 N), TA (776 ± 43 N) and TP (888 ± 64 N) tendons. The stiffness of the single-loop tibialis tendons (236 ± 10 N/mm) was also greater than of the BPTB (168 ± 13 N/mm), TA (60 ± 2 N/mm) and TP (73 ± 5 N/mm) tendons. The cross-sectional area of the BPTB tendons was 67 ± 5 mm², of the single-loop tibialis tendons 36 ± 2 mm², of the TA tendons 20 ± 1 mm², and of the TP tendons 23 ± 1 mm². The elongation of the single-loop tibialis tendons and of the BPTB tendons was almost similar (7 ± 0.4 mm). The same applied to the TA and TP tendons (14 ± 0.6 mm). The results of this in vitro mechanical study suggest that fresh-frozen single-loop TA and TP tendons, and BPTB allografts are an acceptable substitute for hamstrings in anterior cruciate ligament reconstruction.     

Anatomical double-bundle anterior cruciate ligament reconstruction

A careful review of the literature suggests that a significant number of patients undergoing anterior cruciate ligament (ACL) reconstruction have less than optimal results. Although overall outcomes of ACL reconstruction are favourable, there remains considerable room for improvement. Anatomically, the ACL consists of two major functional bundles, the anteromedial and the posterolateral bundle. Biomechanically, both bundles contribute significantly to the anterior and the rotational stability of the knee. Therefore, anatomical double-bundle ACL reconstruction techniques may further improve the outcomes in ACL surgery. Our preferred technique for arthroscopic double-bundle ACL reconstruction includes the use of two femoral and two tibial tunnels to restore both the anteromedial and the posterolateral bundle of the ACL and their anatomical footprints at their tibial and femoral insertion site. We use two tibialis anterior tendon allografts for the restoration of the two ACL bundles. Clinical long-term outcome studies may focus on the evaluation of functional outcomes, restoration of anterior and rotational knee stability, and the risk of degenerative osteoarthritis of the knee joint following anatomical double-bundle ACL reconstruction versus single-bundle ACL reconstruction.     

A biomechanical analysis of matched bone-patellar tendon-bone and double-looped semitendinosus and gracilis tendon grafts

Biomechanical testing was done on 15 matched pairs of central-third bone-patellar tendon-bone and double-looped semitendinosus-gracilis grafts harvested from 15 cadaveric knees. Load to failure, composite graft stiffness, and the modulus of elasticity were calculated for each graft. Specimens were from 2 female and 13 male donors (average age, 40 years; range, 17 to 53). Average load to failure for the patellar tendon grafts was 1784 N (+/- 580), compared with 2422 N (+/- 538) for the hamstring tendon grafts (significantly different). There was no statistically significant difference in stiffness between grafts (patellar tendon, 210 N/mm; hamstring tendon, 238 N/mm). The elastic modulus was 225 MPa (+/- 129) for the patellar tendon grafts and 145 MPa (+/- 58) for the hamstring tendon grafts (significantly different). The average cross-sectional area for the hamstring tendon grafts was 57 mm2, compared with the 45 mm2 for the patellar tendon grafts. The hamstring tendon grafts were significantly stronger than the matched central-third patellar tendon grafts, but the two grafts were similar in stiffness. The patellar tendon grafts had a higher modulus than the hamstring tendon grafts.     

Tensile properties of the human femur-anterior cruciate ligament-tibia complex. The effects of specimen age and orientation

The structural properties of 27 pairs of human cadaver knees were evaluated. Specimens were equally divided into three groups of nine pairs each based on age: younger (22 to 35 years), middle (40 to 50 years), and older (60 to 97 years). Anterior-posterior displacement tests with the intact knee at 30 degrees and 90 degrees of flexion revealed a significant effect of knee flexion angle, but not of specimen age. Tensile tests of the femur-ACL-tibia complex were performed at 30 degrees of knee flexion with the ACL aligned vertically along the direction of applied tensile load. One knee from each pair was oriented anatomically (anatomical orientation), and the contralateral knee was oriented with the tibia aligned vertically (tibial orientation). Structural properties of the femur-ACL-tibia complex, as represented by the linear stiffness, ultimate load, and energy absorbed, were found to decrease significantly with specimen age and were also found to have higher values in specimens tested in the anatomical orientation. In the younger specimens, linear stiffness (242 +/- 28 N/mm) and ultimate load (2160 +/- 157 N) values found when the femur-ACL-tibia complex was tested in the anatomical orientation were higher than those reported previously in the literature. These values provide new baseline data for the design and selection of grafts for ACL replacement in an attempt to reproduce normal knee kinematics.     

Load sharing and graft forces in anterior cruciate ligament reconstructions with the Ligament Augmentation Device

Buckle transducers were used to directly measure load sharing and overall force in three segment (semitendinosus, gracilis, Ligament Augmentation Device) and two segment (patellar tendon, LAD) composite ACL grafts during the application of anteriorly directed loads to a series of five fresh knee specimens with a pneumatic load apparatus. The total graft forces generated in the two segment and three segment composite reconstructions during this immediate postoperative state were highly variable when compared to the normal ACL in each specimen, and were irreproducible among the five specimens. Load sharing among the graft components occurred and was also variable in both reconstructions, with this variation being greater in the three segment graft. The LAD carried an average of 45% of the total graft force in the three segment graft and 28% in the two segment graft. Further work is required to clarify the source of the variability in the total graft force and load sharing observed in this study.     

Interference screw fixation of soft tissue grafts in anterior cruciate ligament reconstruction: part 1: effect of tunnel compaction by serial dilators versus extraction drilling on the initial fixation strength

BACKGROUND: Compaction of the bone-tunnel walls by serial dilation is believed to enhance the interference screw fixation strength of the soft tissue grafts in anterior cruciate ligament (ACL) reconstruction. HYPOTHESIS: Serial dilation enhances the fixation strength of soft tissue grafts in ACL reconstruction over extraction drilling. STUDY DESIGN: Randomized experimental study. METHODS: Initial fixation strength of the doubled anterior tibialis tendon grafts (fixed with a bioabsorbable interference screw) was assessed in 21 pairs of human cadaver tibiae with either serially dilated or extraction-drilled bone tunnels. The specimens were subjected to a cyclic-loading test, and those surviving were then tested using the single-cycle load-to-failure test. RESULTS: During the cyclic-loading test, there were 3 fixation failures in the serially dilated and 6 failures in the extraction-drilled specimens but no significant stiffness or displacement differences between the groups. In the subsequent load-to-failure test, the average yield loads were 473 +/- 110 N and 480 +/- 115 N for the 2 groups respectively (P =.97) and no difference with regard to stiffness or mode of failure. CONCLUSIONS: Serial dilation does not increase the strength of interference fixation of soft tissue grafts in ACL reconstruction over extraction drilling. Clinical Relevance: The results of this experiment do not support the use of serial dilators in ACL reconstruction.     

Effects of a novel sterilization process on soft tissue mechanical properties for anterior cruciate ligament allografts

BACKGROUND: Allograft anterior cruciate ligament reconstruction provides benefits such as earlier return to activities and less pain, but concerns remain regarding potential infection and biomechanical stability. HYPOTHESIS: There is no difference in biomechanical properties of soft tissue allografts treated with the Biocleanse tissue sterilization process compared with irradiated and fresh-frozen allografts. STUDY DESIGN: Controlled laboratory study. METHODS: Thirty-six tibialis anterior allografts were equally divided between Biocleanse, irradiated, and fresh-frozen groups. Grafts were measured for cross-sectional area and looped over a smooth rod with the free sutured ends of the graft fixed in custom clamps. Specimens were tensioned to 10 N for 2 minutes and then loaded between 50 and 300 N for 1000 cycles followed by a failure test. Data for creep (mm); stiffness (N/mm) at cycles 1, 10, 100, and 1000; failure load (N); and failure stress (MPa) were compared with a one-way analysis of variance (P < .05). RESULTS: There were no statistically significant differences in creep between groups. Sterilized groups (irradiated = 144.7 +/- 17.7 N/mm and Biocleanse = 146.5 +/- 28.2N/mm) were significantly stiffer during the first cycle than the fresh-frozen group (117.8 +/- 15.7 N/mm, P < .005) without statistically significant differences for subsequent cycles. There were no differences between groups for either failure load (fresh-frozen = 1665 +/- 291.3 N, irradiated = 1671.9 +/- 290.2 N, Biocleanse = 1651.6 +/- 377.4 N) or failure stress. CONCLUSION: Data for "time-zero" physiologic stiffness and failure loads indicate that the Biocleanse process does not adversely affect the biomechanical properties of the allograft material. CLINICAL RELEVANCE: This novel sterilization technique may provide surgeons with potential allograft material with similar biomechanical properties to native tissue.     

The biomechanical effects of low-dose irradiation on bone-patellar tendon-bone allografts

BACKGROUND: Despite evidence that low-dose irradiation of 2 Mrad (20 kGy) is not virucidal for patellar tendon allografts and reduces tissue strength, many tissue bank protocols include low-dose irradiation. HYPOTHESIS: Maintaining tissue mechanical integrity may be particularly relevant toward accelerated rehabilitation of the injured knee, where the cyclic function of patellar tendon allografts is critical. STUDY DESIGN: Controlled laboratory study. METHODS: The cyclic and failure mechanical properties of paired bone-patellar tendon-bone allografts, with and without current low-dose irradiation of 20 kGy, were evaluated. Specimens were loaded from 50 N to 250 N for 1000 cycles at 0.5 Hz and subsequently loaded to failure at a strain rate of 100% per second. RESULTS: After 1000 cycles, grafts elongated 27% more when irradiated than when not (4.4 +/- 1.5 mm vs 3.4 +/- 1.0 mm; P = .03). Failure load averaged 1965 +/- 512 N for irradiated grafts and 2457 +/- 647 N for nonirradiated grafts (P = .007). CONCLUSIONS: The diminished strength of irradiated grafts may contribute to overt anterior cruciate ligament graft failure, and the increase in cyclic elongation may also be detrimental to graft function. CLINICAL RELEVANCE: These results suggest that one should consider the use of nonirradiated allografts as an alternative to irradiated grafts in anterior cruciate ligament reconstruction.     

A long-term study of anterior cruciate ligament allograft reconstruction

We retrospectively reviewed the long-term clinical outcome of unilateral arthroscopic anterior cruciate ligament (ACL) allograft reconstruction. From October 1995 to December 1997, 64 arthroscopic ACL reconstructions were performed. Multiligamentous knee injuries and ACL injuries in polytrauma patients were excluded and out of the remaining 60 patients 55 were available for follow-up. Three patients had suffered a rerupture caused by major trauma. One patient had a rerupture without significant trauma and one failure was caused by deep infection. These five patients were revised. Fifty patients (36 males, 14 females) were included in the final follow-up. At the time of evaluation, the mean duration of follow-up was 10 years and 6 months. All patients were examined by an independent examiner. Seven patients had an extension lag (<5°) and all patients had a knee flexion of at least 120°, with a mean flexion of 135 ± 5° compared to 135 ± 8°. At the time of follow-up, the median IKDC score was 97 (74–100). The Lysholm scoring scale had a median value of 95 (76–100). The median sports level on the Tegner scale was 6 (4–9). The one-leg-hop test showed a mean value of 95 ± 5%. One patient did not perform the one-leg-hop test because of recent surgery to the Achilles tendon. In conclusion, the tibialis anterior or tibialis posterior tendon allograft ACL reconstruction produced good clinical results in the majority of patients at long-term follow-up.     

高频超声快速诊断急性闭合跟腱断裂临床价值

目的探讨高频超声在快速诊断急性闭合跟腱断裂中的应用价值。方法对急诊收治急性闭合跟腱断裂的100例患者进行高频超声检查,观察损伤跟腱的形态、内部结构及回声改变,判断跟腱损伤程度并将超声诊断结果与急诊手术结果相比较。结果急诊手术结果显示,跟腱完全性断裂85例,高频超声快速诊断均检出,诊断符合率为100%。不完全断裂14例,高频超声漏诊3例,诊断符合率80%。漏诊3例均为微小部分断裂,后被MRI确诊。误诊1例,疑似为跟腱微小囊肿,误诊率1%。结论高频超声可快速诊断急性闭合跟腱断裂,是一种便捷、经济、可靠、无创的诊断方法,为断裂跟腱快速急诊手术提供临床依据。     

跟腱损伤的MRI诊断

目的:评价跟腱损伤的MRI诊断价值。方法:回顾11例有明确踝关节损伤史、经手术证实为跟腱损伤患者的MRI表现,并与手术结果对照。结果:11例MRI均有异常表现,诊断为跟腱完全断裂5例、部分断裂6例。MRI对跟腱的形态及其内部结构显示直接、清晰、完整。跟腱损伤表现为跟腱不均匀增粗,腱内信号增高、紊乱,腱束的连续性完全中断或部分中断。结论:MRI能够直接显示外伤后跟腱的形态、内部结构及周围软组织改变,并能准确显示跟腱完全撕裂与部分撕裂的部位和程度,对临床诊治具有重要指导意义。     

Reconstruction of the anterior cruciate ligament: dynamic strain evaluation of the graft

The study is focused on the biomechanical aspects of the anterior cruciate ligament (ACL) reconstruction procedures with an emphasis on evaluating the dynamic strain of materials commonly used for this purpose. Separate and multiple, equally tensioned strands of hamstring grafts used for the reconstruction of the ACL were biomechanically tested and compared to original ACL and bone-patellar tendon-bone (BPTB) grafts, using tissue samples from cadavers. The study was focused on measuring such material properties as the strength, stiffness, maximum load, and elongation at maximum load of the original ACL, BPTB graft, and single tendon hamstring (gracilis and semitendinosus) grafts, continued by double strands and finally by four-strand graft (STG) evaluation. Fresh-frozen cadaveric knees were used, which had been clamped and tensioned equally. The measurement was performed by drop-weight testing, using a Laser Doppler Vibrometer as a basic sensor of the dynamic movements of the gripping clamps, with parallel correlation by a piezoelectric transducer. The grafts for experiments were obtained from 21-paired knees. The measurement was performed at room temperature (21°C) after 24 h of thawing at 4°C. All the specimens were measured for their response to the dynamic tensile load. The maximum strength values were obtained and calculated for the appropriate section area of the specimen. The tensioned strands of the original ACL showed a maximum average load of 1,246 ± 243 N in the section area of about 30 mm² (max. stress 41.3 MPa); the strands of BPTB grafts showed values of 3,855 ± 550 N in the section area of 80 mm² (max. stress 40.6 MPa); the gracilis tendons showed 925 ± 127 N in the section area of 10 mm² (max. stress 95.1 MPa) and the semitendinosuss yielded a result of 2,050 ± 159 N in the area of 20 mm² (max. stress 88.7 MPa). Of all the materials, the original ACL have the lowest strength and stiffness in respect of their biomechanical properties. BPTB grafts showed a slightly higher value of maximum stress, while both the gracilis and semitendinosus tendons showed double the value of maximum load per section area—tensile stress. Two- and four- combined hamstring strands clamped together and equally tensioned with a drop-weight had the combined tensile strength properties of the individual strands within the estimated range of measurement errors. No significant changes in maximum loads/stresses were observed under impact loading conditions. The results of this study demonstrate that equally tensioned four-strand hamstring-tendon grafts have higher initial tensile properties than those in other varieties of samples. From a biomechanical point of view, they seem to be a reasonable alternative procedure for ACL reconstruction.