Patellar Tendon Allograft Research Articles

Patellar Tendon Repair Using a Patellar Tendon Allograft and External Fixator in Three Dogs

Abstract Objective The aim of this study was to report on complications and outcomes with repair of ruptured canine patellar tendons using primary tenorrhaphy coupled with patellar tendon allograft transplantation and use of a transarticular external skeletal fixator. Materials and Methods This report includes three dogs with acutely ruptured patellar tendons, all of whom had surgical repair using a patellar tendon allograft. Dogs were assessed postoperatively by physical examination, owner input, and/or video review. Functional outcomes were classified as full, acceptable, or unacceptable based on previously established criteria. Results Follow-up time was between 24 and 46 weeks. Two dogs obtained full function and one dog reached acceptable function. The acrylic connecting bars of the external fixator fractured and needed to be replaced in one dog. There were no other problems or complications. There was no evidence of rejection of any allograft. Clinical Significance Primary tenorrhaphy supported by patellar tendon allograft transplantation and transarticular skeletal fixation appears to be a viable option without evidence of patellar tendon allograft rejection and acceptable or full recovery in the three dogs of this report.

Load-to-failure characteristics of patellar tendon allograft superior capsule reconstruction compared with the native superior capsule.

BackgroundThe potential use of a patellar tendon allograft for superior capsular reconstruction has been demonstrated biomechanically; however, there are concerns regarding compromised fixation strength owing to the longitudinal orientation of the fibers in the patellar tendon. Therefore, the purpose of this study was to compare the fixation strength of superior capsule reconstruction using a patellar tendon allograft to the intact superior capsule.MethodsThe structural properties of the intact native superior capsule (NSC) followed by superior capsular reconstruction using a patellar tendon allograft (PT-SCR) were tested in eight cadaveric specimens. The scapula and humerus were potted and mounted onto an Instron testing machine in 20 degrees of glenohumeral abduction. Humeral rotation was set to achieve uniform loading across the reconstruction. Specimens were preloaded to 10 N followed by cyclic loading from 10 N to 50 N for 30 cycles, then load to failure at a rate of 60 mm/min. Video digitizing software was used to quantify the regional deformation characteristics.ResultsDuring cyclic loading, there was no difference found in stiffness between PT-SCR and NSC (cycle 1 – PT-SCR: 12.9 ± 3.6 N/mm vs. NSC: 22.5 ± 1.6 N/mm; P = .055 and cycle 30 – PT-SCR: 27.3 ± 1.4 N/mm vs. NSC: 25.4 ± 1.7 N/mm; P = .510). Displacement at the yield load was not significantly different between the two groups (PT-SCR: 7.0 ± 1.0 mm vs. NSC: 6.5 ± 0.3 mm; P = .636); however, at the ultimate load, there was a difference in displacement (PT-SCR: 20.7 ± 1.1 mm vs. NSC: 8.1 ± 0.5 mm; P < .001). There was a significant difference at both the yield load (PT-SCR: 71.4 ± 2.2 N vs. NSC: 331.6 ± 56.6 N; P = .004) and the ultimate load (PT-SCR: 217.1 ± 26.9 N vs. NSC: 397.7 ± 62.4 N; P = .019). At the yield load, there was a difference found in the energy absorbed (PT-SCR: 84.4 ± 8.9 N-mm vs. NSC: 722.6 ± 156.8 N-mm; P = .005), but no difference in energy absorbed was found at the ultimate load.ConclusionsPT-SCR resulted in similar stiffness to NSC at lower loads, yield displacement, and energy absorbed to ultimate load. The ultimate load of the PT-SCR was approximately 54% of the NSC, which is comparable with the percent of the ultimate load in rotator cuff repair and the intact supraspinatus at time zero.

Aging Decreases the Ultimate Tensile Strength of Bone–Patellar Tendon–Bone Allografts

The purpose of this study was to determine whether aging imparts a clinically significant effect on the (1) mechanism of graft failure and (2) structural, material, and viscoelastic properties of patellar tendon allografts by evaluating these properties in younger donors (≤30 years of age) and older donors (>50 years of age). A total of 34 younger (≤30 years of age) and 34 older (>50 years of age) nonirradiated, whole bone-tendon-bone allografts were prepared for testing by isolating the central third of the patellar tendon using a double-bladed 10-mm width scalpel under a 10-N load to ensure uniformity of harvest. Bone blocks were potted in polymethylmethacrylate within custom molds. Tendon length and cross-sectional area were measured using an area micrometer. A mechanical loading system was used to precondition the grafts for 100 cycles with a load between 50 N and 250 N (1 Hz). A creep load (500 N) was then applied at a rate of 100 mm/min (10 minutes). Grafts were allowed to recover at 1 N (10 minutes), followed by pull-to-failure at a rate of 100% strain per second. Mechanisms of failure (midsubstance vs avulsion) were noted and the structural, material, and viscoelastic properties calculated and compared between groups. There were 33 (97%) midsubstance tears in the younger group and 28 (82%) in the older group (P= .034). Younger grafts showed greater ultimate load to failure (1,782 N [1,533, 2,032] vs 1,319 N [1,103, 1,533]) (P= .006) and ultimate tensile stress (37.4 MPa [32.4, 42.4] vs 27.5 MPa [22.9, 32.0]) (P= .006). There were no significant differences in displacement (P= .595), stiffness (P= .950), strain (P= .783), elastic modulus (P= .114), creep displacement (P= .881), and creep strain (P= .614). This invitro study suggests that aging weakens the bone-tendon junction and decreases the ultimate tensile strength of patellar tendon allografts. However, aging did not affect the displacement, strain, stiffness, elastic modulus, creep displacement, or creep strain of patellar tendon allografts. Surgeons should be aware that patellar tendon allografts from donors >50 years of age have a lower ultimate tensile stress than donors ≤30 years of age.

Immunohistochemical analysis of sensory corpuscles in human transplants of the anterior cruciate ligament

BackgroundSensory nerve endings in ligaments play an important role for the proprioceptive function. Clinical trials show that the sense of body position does not fully recover in the knee joint after reconstructive surgery of the ruptured anterior cruciate ligament. The aim of this study is to identify sensory corpuscles in autogenous and allogenous transplants of the ligament and to compare their quantity between the used allografts and autografts.MethodsThirty-three patients were included in this study. Three patellar tendon allografts, 14 patellar tendon autografts and 12 semitendinosus autografts were harvested during revision surgery after traumatic rerupture of the graft. The control consisted of 4 healthy anterior cruciate ligaments after fresh rupture. After haematoxylin staining, immunohistochemical analysis was performed using antibodies against S100, p75 and PGP9.5. Microscopical examination was carried out, and the number of mechanoreceptors was counted. Statistical analysis was performed using the Mann-Whitney U test.ResultsTwo types of mechanoreceptors were identified in each graft: Ruffini corpuscles and free nerve endings. The number of Ruffini corpuscles per square centimeter was the highest in the control. Comparing the grafts, the highest number of receptors could be detected in the semitendinosus autograft. The amount of free nerve endings was higher in the semitendinosus and patellar tendon autografts than in the control; the allografts showed the lowest number of receptors. With increasing time after reconstruction, the number of both types of receptors showed a decrease in the semitendinosus graft, whereas it increased in the patellar tendon graft and allograft. The number of mechanoreceptors in the semitendinosus and patellar tendon graft decreased over time after graft-failure, whereas it increased slightly in the allograft.ConclusionThis study was the first to identify mechanoreceptors in human transplants of the anterior cruciate ligament. The partial increase in the number of receptors over time after reconstruction could indicate a reinnervation of the grafts.

A biomechanical cadaveric study of patellar tendon allograft as an alternative graft material for superior capsule reconstruction

In a cadaveric irreparable rotator cuff tear model, patellar tendon allograft-superior capsule reconstruction (PT-SCR) will restore glenohumeral stability and reduce subacromial contact pressures without significant graft deformation during testing. Eight cadaveric shoulders were tested in a custom shoulder testing system. Rotational range of motion (ROM), superior translation, and subacromial contact pressure were measured in the following experimental conditions: intact rotator cuff, irreparable supraspinatus tear (massive cuff tear [MCT]), and PT-SCR. MCT and PT-SCR resulted in significantly increased total ROM at all degrees of abduction compared with the intact state (P < .001). In both 0° and 30° of glenohumeral abduction, MCT showed a significant increase in superior translation compared with the intact state (P < .001). Application of the PT-SCR resulted in a decrease of superior translation compared with MCT (P < .001). At 0° abduction/60° external rotation and 0° abduction/90° external rotation, MCT showed significantly greater peak subacromial contact pressure compared with the intact state (P < .006). At both of these positions, PT-SCR was able to reduce peak pressure to lower than or no significant difference from the intact state. There was no statistically significant change in graft thickness, length, or width after testing. PT-SCR was able to reduce superior translation of the humeral head and peak subacromial contact pressure without restricting ROM. Furthermore, there was no significant graft deformation during testing. PT-SCR in this validated cadaveric model demonstrates favorable biomechanical properties and is a viable source of graft material for SCR.

Comparison between two different platelet-rich plasma preparations and control applied during anterior cruciate ligament reconstruction. Is there any evidence to support their use?

To compare the clinical, analytical and graft maturation effects of two different platelet-rich plasma (PRP) preparations applied during anterior cruciate ligament (ACL) reconstruction. A total of 150 patients with ACL disruption were included in the study. Arthroscopic ACL reconstruction with patellar tendon allograft was conducted on all knees using the same protocol. One hundred patients were prospectively randomised to either a group to receive double-spinning platelet-enriched gel (PRP) with leukocytes (n=50) or to a non-gel group (n=50). Finally, we included 50 patients treated with a platelet-rich preparation from a single-spinning procedure (PRGF Endoret(®) Technology) without leukocytes. Inflammatory parameters, including C-reactive protein (CRP) and knee perimeters (PER), were measured 24 hours and 10 days after surgery. Postoperative pain score (visual analogue score [VAS]) was recorded the day after surgery. Follow-up visits occurred postoperatively at 3, 6, and 12 months. The International Knee Documentation Committee scale (IKDC) was included to compare functional state, and MRI was conducted 6 months after surgery. The PRGF group showed a statistically significant improvement in swelling and inflammatory parameters compared with the other two groups at 24 hours after surgery (p<0.05). The results did not show any significant differences between groups for MRI and clinical scores. PRGF used in ACL allograft reconstruction was associated with reduced swelling; however, the intensity and uniformity of the graft on MRI were similar in the three groups, and there was no clinical or pain improvement compared with the control group. II.

Regional mechanical properties of human patellar tendon allografts

Very little is known regarding regional biomechanical properties of patellar tendon allografts. Ten human bone-tendon-bone (BTB) patellar grafts were separated into equal thirds and underwent cyclic and failure testing. Grafts were non-irradiated and processed using proprietary sterilization methods. The central third was the thickest region (4.9±0.4mm) compared to the medial and lateral (p<0.05). The lateral third was the longest region (58.8±8.8mm) compared to the medial (47.9±8.5mm) and central (47.2±8.8mm) portions (p<0.05). Cyclic testing demonstrated no regional differences with respect to elongation (n.s.) and creep strain (n.s.). Failure testing demonstrated increased maximum load and stiffness in the central region (1,680±418N and 278±67N/mm, respectively) as compared to the medial (1,033±214N, p<0.002, 201±37N/mm, p<0.03) and lateral thirds (908±412N, p<0.03, 173±66N/mm, p<0.002). Elongation at maximum load did not vary between regions. Central region maximum stress (41.0±12.5MPa) was greater than that of the medial third (28.1±3.6MPa, p<0.02), with strain at maximum stress larger in the central third (0.21±0.03) compared to lateral (0.16±0.03, p<0.01). The central third of a non-irradiated, human bone-patellar tendon-bone construct is thicker and biomechanically superior to the medial and lateral regions in most respects. These findings reinforce the use of the central third of a patellar tendon allograft in anterior cruciate ligament reconstruction. Further investigations are required to determine whether the decreased biomechanical properties of the medial and lateral third of the BTB construct negatively influence the mechanical function of hemi-BTB grafts.

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

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. 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. 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. 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. IV.

Chlorhexidine Gluconate Cleansing Has No Effect on the Structural Properties of Human Patellar Tendon Allografts

If an anterior cruciate ligament graft somehow becomes contaminated intraoperatively, soaking it in 4% chlorhexidine gluconate has been shown to be the most popular and efficacious method for sterilization before implantation. The purpose of this study was to evaluate the effects of a chlorhexidine soak on the structural properties of human patellar tendon allografts. Sixteen human patellar tendon allografts were randomly split into 2 groups of 8. Grafts in 1 group were soaked in 4% chlorhexidine gluconate for 30 minutes, and the other grafts were kept moist in normal saline-soaked gauze. Data on preload width, preload thickness, elongation, ultimate tensile load, and stiffness were obtained through measurement and mechanical testing of the grafts. Graft donor ages ranged from 29 to 43 years. There was no difference in the mean values of graft dimensions of the chlorhexidine-exposed group versus the normal saline-exposed group before mechanical testing (width of 9.48 mm v 9.56 mm, P = .89; thickness of 4.01 mm v 4.57 mm, P = .34). Graft elongation was not statistically different between the groups (2.52 mm v 1.43 mm, P = .27). No statistically significant difference was noted between the ultimate tensile load (2,219 N v 1,878 N, P = .36) or stiffness (274.3 N/mm v 297.0 N/mm, P = .63) of the grafts in both groups. Structural properties of human patellar tendon allografts are not significantly affected by soaking in 4% chlorhexidine gluconate for 30 minutes. Surgeons wishing to treat an inadvertently contaminated graft intraoperatively with 4% chlorhexidine may do so without concern that such treatment will impact graft strength.

Effect of Donor Age on Patellar Tendon Allograft ACL Reconstruction

Anterior cruciate ligament reconstruction with patellar tendon allograft tissue is a common orthopedic procedure. It is unknown what effect, if any, the donor age has on clinical outcomes. Biomechanical studies have shown the strength of cadaveric patellar tendon to be independent of age, but no clinical studies have evaluated patient outcomes related to this variable. The purpose of this study was to evaluate the effect of allograft donor age on clinical outcomes of patients undergoing allograft anterior cruciate ligament reconstruction with patellar tendon allograft. Case logs were reviewed to identify primary anterior cruciate ligament reconstruction with allograft patellar tendon by a single surgeon using a standard endoscopic transtibial technique with interference screw fixation. Revision and multiligamentous surgeries were excluded. Seventy-seven patients who met these criteria were identified. Allografts were fresh-frozen, aseptically harvested patellar tendons from a single tissue bank. The donor age was obtained. Clinical outcomes were obtained by contacting patients by telephone and retrospective chart review. Pre- and postoperative Lysholm and Tegner knee scores were used for comparison.Data from 75 patients with an average follow-up of 24 months were obtained. Average donor age was 44 years (range, 14-65 years), and average patient age was 37 years (range, 18-60 years). Statistical analysis of pre- and postoperative Lysholm scores demonstrated statistically significant improvement (P≤.001). Using donor age as a continuous variable, no effect was found on postoperative improvement in Lysholm score or Tegner score (P=.6).

Interval Arthrometric Comparison of Anterior Cruciate Ligament Reconstruction Using Bone–Patellar Tendon–Bone Autograft Versus Allograft

Background: There is little information regarding the incremental changes in the postoperative laxity of patellar tendon (PT) autografts versus allografts in anterior cruciate ligament (ACL) reconstruction. Hypotheses: (1) There would be no significant increase in laxity between 6 weeks and 1 year postoperatively with PT autografts or allografts, (2) there would be no significant difference in laxity between PT autografts and allografts, (3) there would not be a significant difference in laxity between nonirradiated and low dose–irradiated PT allograft tissues, and (4) the physical examination findings would correlate with the instrumented laxity outcomes. Study Design: Cohort study; Level of evidence, 3. Methods: A retrospective review of 238 ACL-deficient patients who underwent single-incision endoscopic ACL reconstruction with a PT autograft (n = 132) or allograft (n = 106; 58 irradiated and 48 nonirradiated) from a single surgeon was made looking at data from preoperatively and from 6 weeks to 1 year postoperatively. The objective measurements of ligament integrity included range of motion, Lachman test, pivot-shift test, and KT-1000 arthrometer instrumented laxity examination. Failure was defined as arthrometric side-to-side differences (maximum manual difference) ≥3 mm or a positive pivot shift. Statistical significance was defined as P < .05. Results: There were no differences in postoperative examination findings or instrumented laxity between PT autografts and allografts (irradiated or nonirradiated) in either subgroup. The postoperative improvement based on the Lachman examination, pivot-shift test, and arthrometric data in all study groups was significant (P < .001) in 98% (autograft: n = 130; allograft: n = 104) of patients, and arthrometric failure correlated with failure by physical examination. There was no significant change in graft laxity, as measured by KT-1000 arthrometer, from 6 weeks to 1 year postoperatively for 98% of patients. Finally, there was no statistical correlation in instrumented laxity results for either the autograft or allograft group with reference to age, gender, concurrent meniscectomy, meniscal repairs, interval to surgery, postoperative patellar pain, time to surgery, or irradiated versus nonirradiated allograft. Conclusion: Laxity is not increased after the initial 6 weeks for either PT allograft or autograft constructs during the first postoperative year. There was no correlation between age, gender, concomitant injury, interval to surgery, or radiation of the graft with instrumented laxity results. Furthermore, our arthrometric data paralleled our clinical findings of stability at follow-up.

Cryopreservation with glycerol improves the in vitro biomechanical characteristics of human patellar tendon allografts

To evaluate the in vitro biomechanical characteristics of patellar tendon ligaments (BTB) when stored as fresh frozen or as glycerol cryopreserved allografts. Seventy patellar tendons were harvested from 35 cadaveric human donors and randomly assigned into seven groups. Grafts in group FRESH were mechanically tested within 2 h of harvesting. FROZ-3, FROZ-6, and FROZ-9 were deep-frozen to -80 °C for 3, 6, and 9 months, respectively. Grafts in groups CRYO-3, CRYO-6, and CRYO-9 were initially incubated with 10% glycerol in a phosphate-buffered saline for 1 h and then stored in glycerol solution (10% glycerol in PBS) at -80 °C for 3, 6, and 9 months, respectively. Grafts were mechanically tested with two cycling modes (50-250 °N and 150-500 °N) and then loaded to failure. Cryopreserved grafts demonstrated more consistent results and expressed lower elongation rates after both cycling loading protocols compared to their frozen counterparts at all storage times. During load-to-failure analysis, ultimate stiffness levels were predominantly higher (23.9-61.5%) in cryopreserved grafts compared with frozen grafts, and ultimate stress levels were 26% (13.3-47.7%) higher, regardless of the storage time. Moreover, cryopreserved grafts revealed similar ultimate elongation and uniformly higher ultimate stiffness and ultimate stress levels compared to fresh grafts. The results of this in vitro study demonstrated superior mechanical properties of cryopreserved grafts compared to frozen grafts within a preservation period of 9 months. Cryopreservation with glycerol solution might be used to further improve the quality of preserved soft-tissue allografts.

Revision of anterior cruciate ligament reconstruction with patellar tendon allograft and autograft: 2- and 5-year results

The most common failure reasons of an anterior cruciate ligament (ACL) graft are incorrect positioning of the drill channels and insufficient fixation. In many cases, one-stage revision with patellar tendon graft and the appropriate corrections are possible. For previous use of the ipsilateral patellar tendon third, an allograft seems favorable for reconstruction. So far, no study compared the results of revision surgery of autologous versus allogenous patellar tendon grafts for revision surgery of the ACL in a 5-year follow-up. A retrospective study was conducted to analyze the clinical outcome and stability results 2 years (19.2 ± 5.8 months) and 5 years (68.8 ± 6.8 months) after revision of ACL reconstruction using middle-third patellar tendon allografts and autografts. The allografts were cleansed by mechanical means only. There were 15 patients in the allograft group and 14 in the autograft group. Patients with isolated re-rupture of the ACL graft were included in the study. Clinical results were evaluated by International Knee Documentation Committee 2000 forms (IKDC), Lysholm score, Tegner activity score, and visual analog scale. Stability was evaluated by means of KT-1000 arthrometer, Lachman test, and pivot-shift test. Location of drill holes was evaluated radiologically. Gonarthritis was graded according to Kellgren and Lawrence on the basis of radiographs. There were no significant differences between the two groups in anterior translation, manual examination for stability, IKDC 2000 findings, Tegner activity score, or Lysholm score. Extension deficits were more frequent in the autograft group at the first follow-up (P = 0.010). Lateral gonarthritis and femoral tunnel widening were more common in the allograft group at the second follow-up (P = 0.049 and P = 0.023, respectively). Pain on walking downhill was significantly more frequent in the allograft group at the second follow-up (P = 0.027). The functional results with allografts that had not undergone irradiation or chemical sterilization were comparable to those with autografts in ACL revision surgery. Allografts represent a good alternative to autogenous patellar tendons in revision surgery.

Sterilization with electron beam irradiation influences the biomechanical properties and the early remodeling of tendon allografts for reconstruction of the anterior cruciate ligament (ACL)

Although allografts for anterior cruciate ligament (ACL) replacement have shown advantages compared to autografts, their use is limited due to the risk of disease transmission and the limitations of available sterilization methods. Gamma sterilization has shown detrimental effects on graft properties at the high doses required for sufficient pathogen inactivation. In our previous in vitro study on human patellar tendon allografts, Electron beam (Ebeam) irradiation showed less detrimental effects compared to gamma sterilization (Hoburg et al. in Am J Sports Med 38(6):1134-1140, 2010). To investigate the biological healing and restoration of the mechanical properties of a 34 kGy Ebeam treated tendon allograft twenty-four sheep underwent ACL replacement with either a 34 kGy Ebeam treated allograft or a non-sterilized fresh frozen allograft. Biomechanical testing of stiffness, ultimate failure load and AP-laxity as well as histological analysis to investigate cell, vessel and myofibroblast-density were performed after 6 and 12 weeks. Native sheep ACL and hamstring tendons (HAT, each n = 9) served as controls. The results of a previous study analyzing the remodeling of fresh frozen allografts (n = 12) and autografts (Auto, n = 18) with the same study design were also included in the analysis. Statistics were performed using Mann-Whitney U test followed by Bonferroni-Holm correction. Results showed significantly decreased biomechanical properties during the early remodeling period in Ebeam treated grafts and this was accompanied with an increased remodeling activity. There was no recovery of biomechanical function from 6 to 12 weeks in this group in contrast to the results observed in fresh frozen allografts and autografts. Therefore, high dose Ebeam irradiation investigated in this paper cannot be recommended for soft tissue allograft sterilization.

Resorption and Remodeling of Hydroxyapatite–Poly-L-Lactic Acid Composite Anterior Cruciate Ligament Interference Screws

The purpose of this study was to evaluate the progression of hydroxyapatite-poly-L-lactic acid (HA-PLLA) interference screw resorption and remodeling in patients after anterior cruciate ligament (ACL) reconstruction. Sixty-five patients undergoing ACL reconstruction with patellar tendon autograft or allograft fixed at both the femur and tibia with HA-PLLA screws were evaluated. We evaluated 10 patients each at 2, 3, and 4 years postoperatively, whereas 35 patients were evaluated at 5 years postoperatively. In all patients a physical examination was performed and functional outcome scores and computed tomography (CT) analysis were obtained at follow-up. Screw tract densities determined by CT at 5 years postoperatively were higher than muscle and were similar to the surrounding bone. At 4 years, 80% to 90% of screws were completely resorbed. At 5-year follow-up, 29% of patients showed complete ossification of the screw tract in the femur versus 34% in the tibia. There was no tunnel widening or sclerosis noted. Subjective and objective clinical results remained high throughout the study period. The HA-PLLA interference screws are slowly resorbed over time, and the majority are completely resorbed between 3 and 4 years after ACL reconstruction with patellar tendon autograft or allograft. Osteoconductivity and remodeling were confirmed by CT scans, and no tunnel widening, sclerosis, cysts, or inflammatory changes were noted. Level IV, therapeutic case series.

Arthroscopic single-bundle anterior cruciate ligament reconstruction with six-strand hamstring tendon and patellar tendon allograft

To compare the outcome of arthroscopic single-bundle anterior cruciate ligament (ACL) reconstruction with six-strand hamstring tendon and patellar tendon allograft. From October 2006 to December 2009, 108 patients with arthroscopic single-bundle ACL reconstruction were retrospectively reviewed, with 58 patients with six-strand hamstring tendon (Group H), and 50 patients with patellar tendon allograft (Group P). Patients were available for clinical evaluation with KT-1000 arthrometer measurements, Lachman and pivot-shift test, and knee function with the International Knee Documentation Committee (IKDC), Lysholm scores. All the patients were followed up at an average of 28.6 months (range 12 - 38 months). The average side-to-side difference was lesser for group H (1.2 ± 1.2) mm than group P (1.8 ± 1.5) mm (P < 0.05). On the pivot-shift test, 55 (94.8%) patients were negative and 3 (5.2%) were positive in group H, whereas 41 (82.0%) were negative and 9 (18.0%) were positive in group P, with significant difference between two groups (P < 0.05). All knee function scores were improved postoperatively, without statistically significant difference between the two groups (P > 0.05). Arthroscopic single-bundle ACL reconstruction with six-strand hamstring tendon will achieve better knee stability than patellar tendon allograft.

Effect of Donor Age on Patellar Tendon Allograft Anterior Cruciate Ligament Reconstruction (SS-64)

Introduction ACL reconstruction with patellar tendon allograft tissue is a common orthopaedic procedure. It is unknown what effect, if any, the age of the donor has on clinical outcomes. It has been postulated that increasing the donor age would have negative effects on outcome. Biomechanical studies have shown strength of cadaveric patellar tendon to be independent of age, but no clinical studies have evaluated patient outcomes related to this variable. Methods Case logs were reviewed to identify primary ACL reconstruction with allograft patellar tendon by a single surgeon using a standard endoscopic transtibial technique with interference screw fixation. Revision and multi-ligamentous surgeries were excluded. 83 patients were identified meeting this criteria. Allografts were fresh frozen, aseptically harvested patellar tendons from a single tissue bank. The age of the donor was obtained from the tissue bank. Clinical outcomes were obtained by contacting patients by telephone and retrospective chart review. Pre- and postoperative Lysholm scores as well as activity levels were utilized for comparison. Results Data from 75 patients was obtained with an average follow-up of 24 months. The average donor age was 44 years with a range of 14-65 and the average age of the patient was 37 years. Statistical analysis of pre and postoperative Lysholm scores demonstrated improvement that was statistically significant (p<0.001). Using donor age as a continuous variable, there was no effect on either postoperative Lysholm score (p=0.5) or the postoperative Tegner score (p=0.6). Conclusion ACL reconstruction with patellar tendon allograft has a high success rate that is independent of the age of donor tissue utilized for reconstruction with standard technique. ACL reconstruction with patellar tendon allograft tissue is a common orthopaedic procedure. It is unknown what effect, if any, the age of the donor has on clinical outcomes. It has been postulated that increasing the donor age would have negative effects on outcome. Biomechanical studies have shown strength of cadaveric patellar tendon to be independent of age, but no clinical studies have evaluated patient outcomes related to this variable. Case logs were reviewed to identify primary ACL reconstruction with allograft patellar tendon by a single surgeon using a standard endoscopic transtibial technique with interference screw fixation. Revision and multi-ligamentous surgeries were excluded. 83 patients were identified meeting this criteria. Allografts were fresh frozen, aseptically harvested patellar tendons from a single tissue bank. The age of the donor was obtained from the tissue bank. Clinical outcomes were obtained by contacting patients by telephone and retrospective chart review. Pre- and postoperative Lysholm scores as well as activity levels were utilized for comparison. Data from 75 patients was obtained with an average follow-up of 24 months. The average donor age was 44 years with a range of 14-65 and the average age of the patient was 37 years. Statistical analysis of pre and postoperative Lysholm scores demonstrated improvement that was statistically significant (p<0.001). Using donor age as a continuous variable, there was no effect on either postoperative Lysholm score (p=0.5) or the postoperative Tegner score (p=0.6). ACL reconstruction with patellar tendon allograft has a high success rate that is independent of the age of donor tissue utilized for reconstruction with standard technique.

Primary ACL reconstruction: comparison of Achilles tendon allograft with tibial anatomical fixation and patellar tendon allograft with external aperture fixation

Purpose The purpose of this study was to compare the outcome of primary anterior cruciate ligament (ACL) reconstruction between Achilles tendon allograft with tibial anatomical bifixation and bone-patellar tendon-bone (BPTB) allograft with tibial external aperture fixation.

Patellar Tendon Anterior Cruciate Ligament Reconstruction in the High-Demand Patient: Evaluation of Autograft Versus Allograft Reconstruction

This study sought to compare patient-reported and objective outcomes in high-demand patients after anterior cruciate ligament reconstruction with either patellar tendon allograft or autograft by use of a matched-pairs case-control experimental design. Nineteen matched pairs were obtained based on gender (36.8% female patients), age (27.9 +/- 8.1 years in autograft group v 28.1 +/- 9.1 years in allograft group), and length of follow-up (9.1 +/- 2.7 years in autograft group v 10.3 +/- 2.6 years in allograft group). All patients reported participating in very strenuous (soccer, basketball, and so on) or strenuous (skiing, tennis, and so on) sporting activity 4 to 7 times per week before their knee injury. Patient-reported outcomes included the International Knee Documentation Committee Subjective Knee Form, Activities of Daily Living and Sports Activity Scales of the Knee Outcome Survey, and Short Form 36. Clinical evaluation included knee range of motion, laxity, and functional strength. There were no statistically significant differences in gender, age, or body mass index. There was a slight difference in length of follow-up (P < .05). The groups showed no statistically significant differences in any of the patient-reported or objective outcome measures. More autograft patients reported that they were able to perform very strenuous activity without the sense of instability (14 v 7), but this difference only approached statistical significance (P < .07). Twelve autograft patients were able to return to preinjury levels of sporting activity compared with ten allograft patients. Sixteen autograft patients and twelve allograft patients were able to participate in strenuous or very strenuous sporting activity at follow-up. Both differences were not statistically significant. Autograft and fresh-frozen allograft patellar tendon anterior cruciate ligament reconstruction exhibit similar patient-reported and objective outcomes in high-demand individuals at 3 to 14 years' follow-up. Level III, therapeutic case-control study.

Patellar Tendon Anterior Cruciate Ligament Reconstruction in the High-Demand Patient: A Retrospective Matched Analysis of Autograft Versus Allograft Reconstruction with 3- to 14-year Follow-up (SS-47)

Anterior cruciate ligament (ACL) reconstruction with patellar tendon allograft has been stated to result in increased post-operative laxity and delays in return to sport secondary to slower graft incorporation when compared to patellar tendon autograft tissue. This study sought to compare clinical outcomes in high-demand patients following ACL reconstruction with either patella tendon allograft or autograft using a matched-pairs case-control experimental design. Nineteen matched pairs were obtained based on gender (46.8% Female), age (27.9±8.1yrs autograft vs. 28.1±9.1 allograft), and length of follow-up (9.1±2.7yrs autograft vs. 10.3±2.6 allograft). All patients reported participating in very strenuous (soccer, basketball etc.) or strenuous (skiing, tennis etc.) sporting activity 4-7 times/week prior to their knee injury. Patient-reported outcomes included the IKDC, SAS, ADLS, and SF-36. Clinical outcomes were also evaluated in terms of knee range of motion, laxity, and functional strength testing. There were no significant differences in gender, age, or BMI. There was a slight difference in length of follow-up (p<.05). The groups showed no significant differences in any of the patient-reported or clinical outcome measures. More autograft patients reported that they were able to perform very strenuous activity without knee laxity symptoms (14 vs. 7), but this difference only approached significance (p<.07). Twelve autograft patients were able to return to pre-injury levels of sporting activity compared to ten allograft patients. Sixteen autograft patients and twelve allograft patients were able to participate in strenuous or very strenuous sporting activity at follow-up. Both differences were not significant. While autograft and allograft patellar tendon ACL reconstruction exhibit similar clinical outcomes in high-demand individuals, autogenous patellar tendon grafts may be indicated to allow patients to return to very strenuous levels of activity without experiencing symptoms of knee laxity.