Use of controlled low dose gamma irradiation to sterilize allograft tendons for ACL reconstruction: biomechanical and clinical perspective

Allograft Augmentation of Hamstring Autograft in Anterior Cruciate Ligament Reconstruction Results in Equivalent Outcomes to Autograft Alone

PURPOSE

To examine allograft augmentation of undersized hamstring (HS) autograft tendons at the time of anterior cruciate ligament (ACL) reconstruction, compared with un-augmented autograft HS ACL reconstruction.

METHODS

Patients who underwent ACL reconstruction at our institution between 2005 and 2015 were reviewed. Inclusion criteria included patients who underwent (1) primary ACL reconstruction, (2) use of a hybrid HS autograft with allograft augmentation, and (3) had a minimum 2-year postoperative follow-up. Patients with revision ACL, multiligamentous injuries, all-epiphyseal fixation techniques, or additional procedures beyond chondroplasty or meniscal repair/debridement were excluded. Data collected included demographics, graft size, concomitant procedures, revision operation, revision ACL reconstruction, and patient-reported outcomes.

RESULTS

In total, 59 patients met criteria for inclusion into the hybrid group, and 80 patients were eligible for inclusion into the control group. The average age of the cohort was 22.9 (interquartile range Q1:17, Q3: 38.3), and 51.8% of the patients were female. Seven patients (11.9%) in the hybrid ACL group underwent revision ACL surgery versus 15 (18.8%) in the control group (P = .27). There was no difference in patient-reported outcomes between groups.

CONCLUSIONS

Augmenting an HS ACL autograft that is 8 mm or less with allograft tissue to increase the overall size of the ACL graft shows no difference in overall reoperation or revision of ACL failure. The hybrid autograft/allograft ACL reconstruction patients showed no clinically important difference between groups in patient-reported outcome measures.

LEVEL OF EVIDENCE

Level III, case-control comparative analysis.

Terminal Sterilization of Anterior Cruciate Ligament (ACL) Allografts: A Systematic Review of Outcomes

INTRODUCTION

Anterior cruciate ligament (ACL) injuries are common and reconstruction can be completed with either autograft or allograft tissue. However, there is concern about an increased failure rate with allograft tissue. The purpose of this study was to systematically review the available evidence to determine the effect of irradiation and level of dose on the failure rates of allograft in ACL reconstruction.

METHODS

A literature search was performed using PubMed, Scopus, and Web of Science from January 2000 to September 2013. Inclusion criteria consisted of the following: (1) primary, unilateral, single-bundle allograft ACL procedure, (2) studies with data documenting graft type and terminal sterilization technique, (3) subjective assessments of outcome, and (4) objective assessments of outcome. Studies without reported subjective and objective outcomes and those pertaining to revision ACL reconstruction were excluded. Failures were defined and compared between irradiated and non-irradiated grafts, as well as between grafts irradiated with 1.2 - 1.8 Mrad and those with 2.0 - 2.5 Mrad.

RESULTS

Of the 242 articles identified via initial search, 17 studies met the final inclusion criteria. A total of 1,090 patients were evaluated in this study, all having undergone unilateral primary ACL reconstruction with allograft tissue with 155 failures. The failure rate between non-irradiated (98/687, 14.7%) and irradiated (57/408, 14.0%) was not statistically significant (p = 0.86). Grafts in the high-dose irradiation group (27/135, 20.0%) had a statistically significant higher (p < 0.001) rate of failure than those in the low-dose irradiation group (30/273, 10.6%).

CONCLUSION

The irradiation of an allograft increases the risk of failure after an ACL reconstruction but the use of lower doses of radiation decreases that risk.

Achilles Tendon Augmented Repair Using Human Acellular Dermal Matrix: A Case Series

Achilles tendon ruptures are common in the general population, especially among members of the older demographic occasionally active in sports. Operative treatments provide a lower incidence of rerupture than do nonoperative treatments, although surgical complications remain a concern. The use of a human acellular dermal matrix to augment Achilles tendon repair might reduce the incidence of complications. In the present case series, we describe the outcomes of 9 patients who underwent Achilles tendon repair with acellular dermal matrix augmentation. Functional outcomes were evaluated using the Foot Function Index-Revised long form, and the clinical results were recorded. After a mean average follow-up period of 14.4 (range 12.0 to 20.0) months, the mean Foot Function Index-Revised long form score was 33.0% ± 4.2%. No cases of rerupture or complications that required additional treatment occurred during the observation period. The outcomes we have presented support further evaluation beyond this case series for using a human acellular dermal matrix to augment Achilles tendon repairs.

Allograft Tissue Safety and Technology

Allograft tissues are commonly used by orthopedic surgeons and are processed using a variety of technologies to increase safety and clinical use. For safety, although disease transmission is a tangible risk, this possibility has been dramatically minimized through modern tissue-processing methods. These include steps to prevent processing tissues with unacceptable bioburden through rigorous screening using donor medical and social histories along with microbial testing of recovered tissue and viral testing of donor serum. Potential bioburden is also controlled through aseptic recovery and processing methods and then reduced through disinfection steps that can include antibiotics, detergents, mechanical process, chemical solutions, and terminal sterilization. Processing steps may also include decellularization methods to lower immunogenic potential of some tissues. To enhance fusion potential of bone void fillers, demineralization steps may be used, and the resultant demineralized bone matrices may be combined with a carrier to improve handling. Bone void fillers and osteochondral allografts may also be specially processed to retain a living cellular component. To preserve relevant biological, biochemical, and physical properties of allografts for clinical use and ease of handling, a number of methods may be used which include: (1) refrigeration in media, (2) freeze-drying, (3) cryopreservation, (4) freezing, and (5) media storage at room temperature. As academic and industry research continue to drive advances, the future direction of allograft tissue likely includes injectables, coatings, cellular therapies, and combinations with other materials. The technology approaches outlined here will be further described along with future directions.

How Variable Are Achilles Allografts Used for Anterior Cruciate Ligament Reconstruction? A Biomechanical Study

BACKGROUND

Allograft tendon used in anterior cruciate ligament reconstruction (ACLR) requires sterilization before implantation. Low-dose gamma irradiation is a means of sterilization that may minimize tissue damage.

PURPOSE

To quantify the variability in mechanical properties between low-dose irradiated Achilles tendon allografts used for ACLR.

STUDY DESIGN

Descriptive laboratory study.

METHODS

A total of 15 intact outer-third Achilles tendon allograft specimens were collected from the remains of full Achilles allografts used for intraoperative ACLR at a single hospital. All grafts were obtained from a single tissue bank and underwent proprietary disinfection and low-dose gamma irradiation (1.5-2.5 Mrad). Biomechanical testing was carried out to measure tendon elongation, failure location during tensile testing, maximum stress, maximum strain, and modulus of elasticity. The mean and standard deviation were calculated for each outcome measure, and the variability between specimens was calculated by the coefficient of variation (CV). The effect of donor age on graft material properties was examined by use of linear regression. One-way analysis of variance was performed to compare differences in the mechanical properties across failure locations.

RESULTS

During cyclic testing, tendon elongation averaged 1.4% ± 1.6% with a CV of 118%. During failure testing, the maximum stress averaged 12.2 ± 4.1 MPa, maximum strain averaged 21.0% ± 6.3%, and modulus of elasticity averaged 95.5 ± 30.8 MPa. The CVs for maximum stress, maximum strain, and modulus of elasticity were 34%, 30%, and 32%, respectively. Ten tendons failed in the midsubstance and 5 failed at the tendon-bone enthesis. No differences were noted in mechanical properties between grafts that failed in the midsubstance versus those that failed at the enthesis. Donor age did not correlate with allograft elongation during cyclic load or any of the material property measures during failure testing.

CONCLUSION

The variabilities in the material properties and graft elongation during cyclic loading of Achilles tendon allografts used in ACLR fall within the range of properties reported in the literature for other ACLR allografts. Material properties do not differ by donor age or graft failure location observed during failure testing.

CLINICAL RELEVANCE

Surgeons should be aware that there exists considerable variation in the mechanical properties of Achilles allograft tendons used for ACLR. This variability is difficult to detect by tissue bank screening or the treating surgeon's inspection and may contribute to the heterogeneity in outcomes of allograft ACLR.

Comparison of Clinical Outcomes After Anterior Cruciate Ligament Reconstruction Using a Hybrid Graft Versus a Hamstring Autograft

PURPOSE

This study aimed to compare the clinical outcomes of patients who underwent anterior cruciate ligament (ACL) reconstruction with a hybrid graft versus an autograft after 3 years of follow-up.

METHODS

Among 57 patients with an ACL injury who underwent ACL reconstruction, 28 patients received a hybrid graft (gracilis and semitendinosus tendon autograft plus a soft tissue allograft) and 29 patients received an autograft (gracilis and semitendinosus tendon autograft). The 2 groups were compared after a minimum 3-year follow-up regarding International Knee Documentation Committee (IKDC) assessment of knee function and stability, pivot-shift test, Lachman test, and KT-1000 side-to-side differences. The patient-reported Tegner activity score, Lysholm score, and subjective IKDC score were also compared. Graft failures were identified by patient-reported outcomes, physical examinations, or magnetic resonance imaging, and were confirmed on second-look arthroscopy; failure rate was compared between groups.

RESULTS

At final follow-up, the 2 groups significantly differed in pivot-shift test result (P = .013) and Lachman test result (P = .027). The failure rate tended to be greater in the hybrid graft group (14.3%) than in the autograft group (3.4%) (P = .148). All 5 patients with failed graft reconstruction were revised after second-look arthroscopy. The KT-1000 side-to-side differences at final follow-up were significantly inferior in the hybrid graft group (3.5 ± 2.0) compared with the autograft group (2.5 ± 1.0, P = .024). The hybrid graft group also had a lower mean Lysholm score (P = .000) and subjective IKDC score (P = .006) than the autograft group. The mean Tegner activity score was 6.8 ± 0.8 in the hybrid graft group and 6.9 ± 0.6 in the autograft group (P = .436).

CONCLUSIONS

The knee stability and patient-reported scores in the autograft-irradiated allograft hybrid graft ACL reconstruction group were significantly inferior compared with those in the autograft ACL reconstruction group.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

"Proprietary Processed" Allografts: Clinical Outcomes and Biomechanical Properties in Anterior Cruciate Ligament Reconstruction

BACKGROUND

The processing of allograft tissues in anterior cruciate ligament (ACL) reconstruction continues to be controversial. While high-dose irradiation of grafts has received scrutiny for high failure rates, lower dose irradiation and "proprietary-based" nonirradiated sterilization techniques have become increasingly popular, with little in the literature to evaluate their outcomes. Recent studies have suggested that the specifics of allograft processing techniques may be a risk factor for higher failure rates.

PURPOSE

To assess these proprietary processes and their clinical outcomes and biomechanical properties.

STUDY DESIGN

Systematic review.

METHODS

A systematic review was performed using searches of PubMed, EMBASE, Google Scholar, and Cochrane databases. English-language studies were identified with the following search terms: "allograft ACL reconstruction" (title/abstract), "novel allograft processing" (title/abstract), "allograft anterior cruciate ligament" (title/abstract), "anterior cruciate ligament allograft processing" (title/abstract), or "biomechanical properties anterior cruciate ligament allograft" (title/abstract). Duplicate studies, studies not providing the allograft processing technique, and those not containing the outcomes of interest were excluded. Outcomes of interest included outcome scores, complication and failure rates, and biomechanical properties of the processed allografts.

RESULTS

Twenty-four studies (13 clinical, 11 biomechanical) met inclusion criteria for review. No demonstrable difference in patient-reported outcomes was appreciated between the processing techniques, with the exception of the Tutoplast process. The clinical failure rate of the Tutoplast process was unacceptably high (45% at 6 years), but no other difference was found between other processing techniques (BioCleanse: 5.4%; AlloTrue: 5.7%; MTF: 6.7%). Several studies did show an increased failure rate, but these studies either combined processing techniques or failed to delineate enough detail to allow a specific comparison for this study. The biomechanical studies showed overall maintenance of satisfactory biomechanical properties throughout multiple testing modes with normalization to the percentage of control specimens.

CONCLUSION

A comparison of proprietary allograft processing techniques is difficult because of the variability and lack of specificity of reporting in the current literature. Among the available literature, except for the Tutoplast process, no notable differences were found in the clinical outcomes or biomechanical properties. Future study with a longer follow-up is necessary to determine the role and limitations of these grafts in the clinical setting.

The efficacy and sterilisation of human decellularised dermal allografts with combinations of cupric ions and hydrogen peroxide

Decellularised tissue allografts have been used in reconstructive surgical applications and transplantation for many years. Some of the current methods of sterilisation have a detrimental effect on the tissue graft structure and function. The anti-microbial activity of cupric ions and hydrogen peroxide (H₂O₂) are well known however their combined application is not currently utilised as a decontamination agent in the tissue banking world sector. The aim of this study was to determine the combined concentrations of copper chloride (CuCl₂) and H₂O₂ that have the optimal bactericidal and sporicidal activity on decellularised (dCELL) human dermis. The first part of this study established the decimal reduction time (D-value) of CuCl₂ (0.1 mg/L and 1 mg/L) together with H₂O₂ (0.01, 0.1, 0.5 and 1%) for Staphylococcus epidermidis, Escherichia coli and Bacillus subtilis spores. The second part of this study identified the most effective CuCl₂ and H₂O₂ concentration that decontaminated dCELL human dermis inoculated with these pathogens. Of all the concentrations tested, 0.1 mg/L CuCl₂ in combination with 1% H₂O₂ had the shortest D-value; S. epidermidis D = 3.15 min, E. coli D = 2.62 min and B. subtilis spores D = 18.05 min. However when adsorbed onto dCELL dermis, S. epidermidis and E. coli were more susceptible to 1 mg/L CuCl₂ together with 0.5% H₂O₂. These studies show promise of CuCl₂-H₂O₂ formulations as potential sterilants for decellularised dermal allografts.

Cyclic Testing of 3 Medial Patellofemoral Ligament Reconstruction Techniques

Background:

Several techniques are available to secure the graft to the patella during medial patellofemoral ligament (MPFL) reconstruction. The biomechanical properties of these techniques remain unknown.

Purpose:

To compare the biomechanical properties of 3 MPFL patellar fixation techniques: bone tunnels (BT), PushLock anchors (PL), and tenodesis screws (TS).

Study Design:

Controlled laboratory study.

Methods:

Forty-five MPFL reconstructions were performed using 3 different reconstruction techniques (BT, PL, and TS). The specimens were randomly assigned, with 15 specimens in each of the 3 groups. Cyclic loading (500 cycles) and load-to-failure testing were performed. Gap formation after 100 and 500 cycles, ultimate load to failure, and stiffness were measured.

Results:

Six constructs failed during cyclic loading, 5 in the PL group (33%) and 1 in the TS group (6.7%). After 100 cycles, differences in gap formation were found between the PL and BT groups (4.48 vs 3.62 mm, P < .03) and between the PL and TS groups (4.48 vs 2.28 mm, P < .0001). After 500 cycles, differences in gap formation were found between the BT and TS groups (6.63 vs 4.16 mm, P < .002) and between the PL and TS groups (7.89 vs 4.16 mm, P < .005). The PL group was found to have a lower ultimate load to failure when compared with the BT group (161.4 vs 258.3 N, P = .019) and the TS group (161.4 vs 237.1 N, P = .009). Group differences in stiffness did not reach statistical significance among the 3 groups (PL, 33.72 N/mm; BT, 37.50 N/mm; TS, 43.00 N/mm).

Conclusion:

The TS and BT groups have more ideal biomechanical properties than the PL group, as demonstrated by less displacement during cyclic loading and a higher load to failure.

Clinical Relevance:

Fixation of the patellar limbs during MPFL reconstruction may be optimized with the use of TS or BT over a PL technique.

A randomized clinical trial of a human acellular dermal matrix demonstrated superior healing rates for chronic diabetic foot ulcers over conventional care and an active acellular dermal matrix comparator

This study compared the efficacy and safety of a human acellular dermal matrix (ADM), D-ADM, with a conventional care arm and an active comparator human ADM arm, GJ-ADM, for the treatment of chronic diabetic foot ulcers. The study design was a prospective, randomized controlled trial that enrolled 168 diabetic foot ulcer subjects in 13 centers across 9 states. Subjects in the ADM arms received one application but could receive one additional application of ADM if deemed necessary. Screen failures and early withdrawals left 53 subjects in the D-ADM arm, 56 in the conventional care arm, and 23 in the GJ-ADM arm (2:2:1 ratio). Subjects were followed through 24 weeks with major endpoints at Weeks 12, 16, and 24. Single application D-ADM subjects showed significantly greater wound closure rates than conventional care at all three endpoints while all applications D-ADM displayed a significantly higher healing rate than conventional care at Week 16 and Week 24. GJ-ADM did not show a significantly greater healing rate over conventional care at any of these time points. A blinded, third party adjudicator analyzed healing at Week 12 and expressed "strong" agreement (κ = 0.837). Closed ulcers in the single application D-ADM arm remained healed at a significantly greater rate than the conventional care arm at 4 weeks posttermination (100% vs. 86.7%; p = 0.0435). There was no significant difference between GJ-ADM and conventional care for healed wounds remaining closed. Single application D-ADM demonstrated significantly greater average percent wound area reduction than conventional care for Weeks 2-24 while single application GJ-ADM showed significantly greater wound area reduction over conventional care for Weeks 4-6, 9, and 11-12. D-ADM demonstrated significantly greater wound healing, larger wound area reduction, and a better capability of keeping healed wounds closed than conventional care in the treatment of chronic DFUs.

Clinical Outcomes in Breast Reconstruction Patients Using a Sterile Acellular Dermal Matrix Allograft

BACKGROUND

Human acellular dermal matrices (ADMs) have enabled successful breast reconstructions while decreasing muscle donor morbidity and pain for the patient. However, some literature reports indicate an increase in complications, especially infection. The decellularization and terminal sterilization properties of DermACELL (D-ADM), a human ADM, may reduce the rate of complications in augmented breast reconstruction while still maintaining successful outcomes. In the study presented here, we evaluate the quality and safety of outcomes with the use of D-ADM during tissue expander breast reconstruction.

METHODS

A retrospective chart review was conducted of patients who underwent breast reconstruction with the use of D-ADM, at a single-military hospital-based practice, resulting in a population of 38 subjects and 58 breasts who had breast reconstruction augmented with D-ADM.

RESULTS

Fifty-six breasts (96.6%) in thirty-six patients demonstrated successful outcomes with a median 27 weeks' time to complete healing. Post-reconstruction radiation and chemotherapy were applied to 24.1 and 25.9% of reconstructions, respectively. Complications rates were minimal with rates of 1.7% for surgical site infection and 1.7% for red breast syndrome.

CONCLUSION

The low complication rates combined with the high success and patient satisfaction rates observed for D-ADM support the use of this ADM in breast reconstruction.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these evidence-based medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Biological incorporation of human acellular dermal matrix used in Achilles tendon repair

Human acellular dermal matrices (ADMs) are used successfully in a variety of procedures, including sports medicine related, wound repair, and breast reconstructions, but the mechanism of repair is still not fully understood. An opportunity to explore this mechanism presented itself when a patient experienced a rerupture of the native tendon due to a fall that occurred 2 months after undergoing an Achilles tendon repair using Matracell treated ADM. The ADM was removed and an extensive histology analysis was performed on the tissue. Additionally, a literature review was conducted to determine the mechanism of ADM integration into the tendon structure and explore if differences in this mechanism exist for different types of human ADMS. The histology analysis demonstrated that the healing process during a tendon reconstruction procedure is similar to that of wound healing. Furthermore, the literature review showed that differences exist in the mechanism for integration among various human ADMs and that these differences may be due to variances in the methods and technologies that manufactures use to process human ADMs.

Does a different dose of gamma irradiation have the same effect on five different types of tendon allografts? - a biomechanical study

INTRODUCTION

The goals of our study were to evaluate the biomechanical differences between five tendons and the changes in biomechanical properties caused by irradiation.

METHODS

Achilles, quadriceps, semitendinosus + gracilis (STG), tibialis anterior (TA) and the peroneus longus (PL) were harvested from 30 donors. Group A contained 50 tendons without gamma irradiation. The groups were irradiated with a dose of 21 kGy (group B 50 tendons) and with a dose of 42 kGy (group C 50 tendons). The grafts were soaked in a radio-protectant solution and frozen at -80 °C. Cyclic loading tests were performed followed by load to failure tests. Young modulus of elasticity, maximum force, strain at tensile strength and strain at rupture were calculated.

RESULTS

The Achilles tendons had significantly lower Young modulus than the TA (p = 0.0036) in group A. The Achilles showed significantly lower than PL (p = 0.000042) and TA (p = 0.00142) in group B and C. The quadriceps and the ST (p = 0.0037) provided poorer values than the TA (p = 0.0432) in group C. We found no difference in maximum loads among the tendons in group A. The maximum load of the Achilles and quadriceps showed better results than the PL (p = 0.0016), (p = 0.0018) and the STG (p = 0.0066), (p = 0.0019) in group C. The TA had similar results like the Achilles and quadriceps.

DISCUSSION AND CONCLUSIONS

The vulnerability of gamma irradiation of TA was less than Achilles and quadriceps tendons.

Maximum load to failure of high dose versus low dose gamma irradiation of anterior cruciate ligament allografts: A meta-analysis

BACKGROUND

The objective of this study was to systematically evaluate the existing literature to compare the biomechanical effects of low dose and high dose gamma irradiation on commonly used ACL allografts.

METHODS

A systematic search was performed in PubMed, Cumulative Index for Nursing and Allied Health Literature (CINAHL), Cochrane Reviews, SCOPUS, and SportDiscus. Nine studies were identified that met the following inclusion criteria: 1) controlled laboratory study, 2) investigation of standard allografts for anterior cruciate ligament reconstruction (ACLR), 3) gamma irradiation (dose reported) and a negative control group, and 4) mechanical loading (results reported).

RESULTS

Nine studies met all inclusion and exclusion criteria. There was a dose-dependent relationship between radiation and decreased mechanical tendon integrity. Low dose radiation (<2.5Mrad [Mrad]) showed graft weakening with an average of 4.3% decrease in load to failure (standardized mean difference [SMD], 0.23; 95% CI 0.216, 0.68; p=0.31), whereas high-dose radiation showed a significantly larger (32.4% average) decrease in load to failure (SMD, 1.79; 95% CI 1.194, 2.38; p<0.001).

CONCLUSIONS

Gamma irradiation has a negative effect on tendon allograft strength that is dose-dependent, with particularly large effects noted at irradiation doses of ≥2.5Mrad.

Allograft tissue irradiation and failure rate after anterior cruciate ligament reconstruction: A systematic review

AIM: To evaluate whether anterior cruciate ligament (ACL) allograft irradiation is effective for sterility without compromising graft integrity and increasing failure rate.

METHODS: A literature search was conducted using PubMed, Cochrane, and Google. The following search terms were used: “Gamma irradiation AND anterior cruciate ligament AND allograft” with a return of 30 items. Filters used included: English language, years 1990-2015. There were 6 hits that were not reviewed, as there were only abstracts available. Another 5 hits were discarded, as they did not pertain to the topic of interest. There were 9 more articles that were excluded: Three studies were performed on animals and 6 studies were meta-analyses. Therefore, a total of 10 articles were applicable to review.

RESULTS: There is a delicate dosing crossover where gamma irradiation is both effective for sterility without catastrophically compromising the structural integrity of the graft. Of note, low dose irradiation is considered less than 2.0 Mrad, moderate dose is between 2.1-2.4 Mrad, and high dose is greater than or equal to 2.5 Mrad. Based upon the results of the literature search, the optimal threshold for sterilization was found to be sterilization at less than 2.2 Mrad of gamma irradiation with the important caveat of being performed at low temperatures. The graft selection process also must include thorough donor screening and testing as well as harvesting the tissue in a sterile fashion. Utilization of higher dose (≥ 2.5 Mrad) of irradiation causes greater allograft tissue laxity that results in greater graft failure rate clinically in patients after ACL reconstruction.

CONCLUSION: Allograft ACL graft gamma irradiated with less than 2.2 Mrad appears to be a reasonable alternative to autograft for patients above 25 years of age.

DermACELL: Human Acellular Dermal Matrix Allograft A Case Report

Diabetes often causes ulcers on the feet of diabetic patients. A 56-year-old, insulin-dependent, diabetic woman presented to the wound care center with a Wagner grade 3 ulcer of the right heel. She reported a 3-week history of ulceration with moderate drainage and odor and had a history of ulceration and osteomyelitis in the contralateral limb. Rigorous wound care, including hospitalization; surgical incision and drainage; intravenous antibiotic drug therapy; vacuum-assisted therapy; and a new room temperature, sterile, human acellular dermal matrix graft were used to heal the wound, save her limb, and restore her activities of daily living. This case presentation involves alternative treatment of a diabetic foot ulcer with this new acellular dermal matrix, DermACELL.

Structural mechanical properties of radiation-sterilized human Bone-Tendon-Bone grafts preserved by different methods

To avoid the risk of infectious disease transmission from donor to recipient, allografts should be terminally sterilized. In the previous paper (Kaminski et al. in Cell Tissue Bank 10:215–219, 2009) we presented the effect of various methods of preservation (deep fresh freezing, glycerolization, lyophilization), followed by irradiation with different doses of electron beam (EB), on material (intrinsic) mechanical properties of human patellar tendons cut out as for anterior cruciate ligament reconstruction, obtained in failure tensile test. As structural mechanical properties are equally important to predict the behaviour of the graft as a whole functional unit, the purpose of the present paper was to show the results for failure load and elongation, obtained in the same experiment. Paired Bone-Tendon-Bone grafts (BTB) were prepared from cadaveric human patella tendons with both patellar and tibial attachments. They were preserved by deep freezing, glycerolization or lyophilization and subsequently EB-irradiated with the doses of 25, 35, 50 or 100 kGy (fresh-frozen grafts) or a single dose of 35 kGy (glycerolized and lyophilized grafts). Each experimental (irradiated) group was provided with control (non-irradiated), donor-matched group. The specimens from all groups were subjected to mechanical failure tensile test with the use of Instron system in order to measure their structural properties (failure load and elongation). All lyophilized grafts were rehydrated before mechanical testing. In our study we did not observe significant deterioration of structural mechanical properties of BTB grafts processed by fresh-freezing and then terminal sterilized with growing doses of EB up to 100 kGy. In contrast, BTB grafts processed by glycerolization or lyophilization and irradiated with 35 kGy showed significant decrease of failure load. Obtained results suggest that deep-frozen irradiated grafts retain their initial mechanical properties to an extent which does not exclude their clinical application. However, biomechanical investigations constitute only the first step to evaluate the potential clinical usefulness of such allografts and further extensive in vivo studies are needed.

Increased Failure Rates After Anterior Cruciate Ligament Reconstruction With Soft-Tissue Autograft-Allograft Hybrid Grafts

PURPOSE

To compare the rate of failure between a group of patients who underwent anterior cruciate ligament (ACL) reconstruction with an autograft-allograft hybrid soft-tissue graft and a matched group of patients who underwent ACL reconstruction with hamstring autograft.

METHODS

From 2007 to 2012, 29 patients underwent hybrid ACL reconstruction performed by 4 fellowship-trained sports medicine surgeons at a single institution. Patients who underwent ACL reconstruction with hamstring autograft comprised the control group and were matched to patients in the hybrid group by sex, age, date of surgery, reconstruction technique, and method of femoral fixation. Graft failure was defined as revision ACL reconstruction or complete graft rupture on magnetic resonance imaging. Graft compromise was defined as magnetic resonance imaging evidence of partial graft rupture or arthroscopically identified partial graft rupture. Lysholm Knee Scoring Scale and International Knee Documentation Committee scores were obtained.

RESULTS

Both groups included 10 men and 19 women, with a mean postoperative follow-up period of 44.4 ± 16.9 months in the hybrid group and 48.0 ± 15.2 months in the control group. Follow-up was obtained in 25 of 29 patients (86.2%) in the hybrid group, and each was matched to 1 patient who received hamstring autograft. The failure rate was 13.8% (4 of 29 patients) in the hybrid group compared with 3.4% (1 of 29) in the control group (P = .160). An additional 27.6% of hybrid group patients (7 of 29) had compromised grafts as defined earlier, as compared with 1 (3.4%) of the control patients (P = .022). Thus the overall hybrid graft failure/compromise rate was 37.9% (11 of 29) compared with 6.9% (2 of 29) for the hamstring autograft group (P = .005). In the hybrid group, the Lysholm score (80.2 ± 12.1) was significantly lower than that in the control autograft ACL group (89.9 ± 11.8) (P = .030). The International Knee Documentation Committee score for the hybrid ACL group (71.26 ± 19.5) was significantly worse than that for the autograft ACL group (85.7 ± 13.0) (P = .012).

CONCLUSIONS

Allograft-autograft hybrid hamstring ACL grafts fail or become structurally compromised at a higher rate than matched autograft hamstring controls.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Bioabsorbable fish scale for the internal fixation of fracture: a preliminary study

Fish scales, which consist of type I collagen and hydroxyapatite (HA), were used to fabricate a bioabsorbable bone pin in this study. Fresh fish scales were decellularized and characterized to provide higher biocompatibility. The mechanical properties of fish scales were tested, and the microstructure of an acellular fish scale was examined. The growth curve of a myoblastic cell line (C2C12), which was cultured on the acellular fish scales, implied biocompatibility in vitro, and the morphology of the cells cultured on the scales was observed using scanning electron microscopy (SEM). A bone pin made of decellularized fish scales was used for the internal fixation of femur fractures in New Zealand rabbits. Periodic X-ray evaluations were obtained, and histologic examinations were performed postoperatively. The present results show good cell growth on decellularized fish scales, implying great biocompatibility in vitro. Using SEM, the cell morphology revealed great adhesion on a native, layered collagen structure. The Young's modulus was 332 ± 50.4 MPa and the tensile strength was 34.4 ± 6.9 MPa for the decellularized fish scales. Animal studies revealed that a fish-scale-derived bone pin improved the healing of bone fractures and degraded with time. After an 8-week implantation, the bone pin integrated with the adjacent tissue, and new extracellular matrix was synthesized around the implant. Our results proved that fish-scale-derived bone pins are a promising implant material for bone healing and clinical applications.

Analysis of irradiation on the clinical effectiveness of allogenic tissue when used for primary anterior cruciate ligament reconstruction

BACKGROUND

It is unclear whether the use of low-dose irradiation or other tissue-processing methods, such as preservation by fresh-frozen (FF), freeze-drying (FD), or cryopreservation (CP) methods, affects the clinical outcomes of primary anterior cruciate ligament reconstruction (ACLR) using allograft.

HYPOTHESIS

Low-dose gamma irradiation (<2.5 Mrad) and method of allograft preservation do not affect subjective and objective clinical outcomes after primary ACLR in studies reviewed between November 2010 and September 2012.

STUDY DESIGN

Systematic review; Level of evidence, 3.

METHODS

A computerized search of multiple electronic databases was conducted from November 2010 to September 2012 for prospective and retrospective studies involving primary allograft ACLR. Inclusion criteria were English-language publications with a minimum average of 2 years' follow-up. Studies were excluded if they involved revision surgery, open surgery, multiple ligament procedures, autograft, xenograft, meniscal allograft, skeletally immature patients, or grafts treated with ethylene oxide, Tutoplast, or irradiation>2.5 Mrad or if the tissue-processing methods were not specified. Clinical outcomes were evaluated using the Lysholm score, Tegner score, International Knee Documentation Committee (IKDC) score, KT-1000/2000 arthrometer score, Lachman test, and pivot-shift test, as well as by assessing complications related to graft rupture, revision surgery, and infections.

RESULTS

A total of 21 publications met the criteria, involving a total of 1453 patients, with 415 irradiated and 1038 nonirradiated allografts. Mean follow-up was 49.8 months (range, 12-170 months). Mean age of the patients was 32.2 years. Knees with nonirradiated allografts had higher mean Lysholm scores (89.8 vs 84.4; P<.05), and a higher proportion of <5-mm difference on KT-1000/2000 arthrometer (0.97 vs 0.84; P<.0001), grade 0 and 1 pivot-shift (0.99 vs 0.94; P<.0001), and grade 0 and 1 Lachman (0.94 vs 0.89; P<.01) than those with irradiated grafts. Knees with irradiated allografts had a higher proportion of grade A and B IKDC outcomes (0.91 vs 0.86; P<.05) and revision surgery (0.0250 vs 0.0022; P<.001) compared with those with nonirradiated allografts. The lack of data for FD and CP allografts meant no statistical analysis could be made comparing FF versus FD versus CP allografts. The effect of irradiation was similar within FF allografts. The effect of graft type and surgical technique could not be determined because of insufficient data.

CONCLUSION

These results suggest that primary ACLRs using nonirradiated allografts may provide superior clinical outcomes than those using low-dose (<2.5 Mrad) irradiated grafts.

RT-PCR testing of allograft musculoskeletal tissue: is it time for culture-based methods to move over?

Allograft musculoskeletal tissue samples are assessed for microbial bioburden to reduce the risk of post-transplant infection. Traditionally, solid agar and broth culture media have been used however, nucleic acid testing, such as real-time (RT) polymerase chain reaction (PCR), has been described as more sensitive. This study evaluated the recovery of low numbers of challenge organisms from inoculated swab and musculoskeletal biopsy samples using solid agar culture, cooked meat medium, blood culture bottles and a RT-PCR assay. It was found that broth culture methods were the most sensitive with RT-PCR unable to detect low numbers of bacteria from these samples. Investigation of other non-culture methods may be worthwhile.

DermACELL: a novel and biocompatible acellular dermal matrix in tissue expander and implant-based breast reconstruction

BACKGROUND

Acellular dermal matrices present a new alternative to supporting expanders and implants for breast reconstruction in breast cancer patients following mastectomy. However, some studies have suggested that acellular dermal matrix may increase the complication rates in certain clinical settings. DermACELL acellular dermal matrix offers advanced processing in order to attempt to decrease bio-intolerance and complications.

METHODS

Ten consecutive patients that presented for breast reconstruction and were candidates for tissue expanders underwent the procedure with the use of an acellular dermal matrix. The patients underwent postoperative expansion/adjuvant cancer therapy, then tissue expander exchange for permanent silicone breast prostheses. Patients were followed through the postoperative course to assess complication outcomes. Histologic evaluation of host integration into the dermal matrix was also assessed.

RESULTS

Of the ten patients, eight completed reconstruction while two patients failed reconstruction. The failures were related to chronic seromas and infection. Histology analysis confirms rapid integration of mesenchymal cells into the matrix compared to other acellular dermal matrices.

CONCLUSIONS

Based on our observations, DermACELL is an appropriate adjunct to reconstruction with expanders. Histological analysis of vascularization and recellularization support the ready incorporation of DermACELL into host tissue. Level of Evidence: Level IV, therapeutic study.