Non-cross-linked porcine acellular dermal matrix in revision breast surgery: long-term outcomes and safety with neopectoral pockets

Systematic Review of Capsular Contracture Management following Breast Augmentation: An Update

BACKGROUND

Capsular contracture is one of the most frequent indications for revision following breast augmentation. Management goals focus on restoring breast aesthetics and minimizing subsequent recurrence of capsular contracture. As new data emerge, close review of the data are merited to build evidence-based clinical guidelines to inform surgical practice and management of capsular contracture.

METHODS

A systematic review of the MEDLINE, Embase, and Cochrane Database of Systematic Reviews databases was conducted to characterize the surgical management of capsular contracture in revision breast augmentations. The primary endpoint was capsular contracture recurrence rate.

RESULTS

The review was conducted in November of 2021. Primary search revealed 14,163 results. Initial screening by title left 1223 articles. Abstract review left 90 articles for full-text review, of which 34 were ultimately included and were all observational in nature.

CONCLUSIONS

Capsular contracture management remains an important topic, with limited high-level evidence for establishing clear evidence-based treatment guidelines. Although more evidence is required to assess the effects of capsulectomy, implant exchange, and plane change, these appear to be useful mechanisms for reducing recurrent capsular contracture. There is more evidence regarding the use of acellular dermal matrix, although this still requires long-term follow-up studies. New developments regarding textured implants limit the revision breast augmentation surgeon to smooth devices.

Efficacy of Acellular Dermal Matrix Type in Treatment of Capsular Contracture in Breast Augmentation: A Systematic Review and Meta-Analysis

BACKGROUND

Capsular contracture is a known complication of breast augmentation and is among the top reasons for revisional breast augmentation procedures. The use of acellular dermal matrix (ADM) has been shown to reduce the rate of capsular contracture in breast reconstruction and augmentation, theorizing that it acts as a protective barrier between the implant capsule and inflammatory process responsible for capsular contracture. The role of ADM in treatment of capsular contracture has been investigated in numerous studies, with a variety of ADMs.

OBJECTIVES

The aim of this study was to perform a systematic review of existing literature on the use of ADM for treatment of capsular contracture in aesthetic breast augmentation patients to investigate differences in efficacy of ADM types.

METHODS

The PubMed, Embase, and CINAHL databases were systematically reviewed for articles pertaining to capsular contracture, acellular dermal matrices, and breast augmentation. Number of patients, type of ADM, Baker grade, follow-up time, complication rate, and capsular contracture rate were recorded from identified articles. Data was pooled from studies to calculate a capsular contracture rate for each ADM type, with a chi-squared test performed for analysis. Identified studies with a comparative group were included in a meta-analysis utilizing risk ratio (RR) to assess the efficacy of ADM.

RESULTS

Nine articles including ADM for treatment of capsular contracture in breast augmentation met criteria for inclusion, with a total of 481 breasts. Strattice was the most commonly utilized ADM (n = 391), followed by AlloDerm (n = 57). There was a statistically significant difference in efficacy of ADM among the studied ADM types (P < .001). AlloDerm, FlexHD, and DermaMatrix had the lowest capsular contracture rates (0%). NeoForm and SurgiMend had the highest capsular contracture rates (each 25%, but with n = 4 and n = 8, respectively). Strattice had a capsular contracture rate of 1.53% in the pooled data, and meta-analysis showed that Strattice reduced the risk of capsular contracture (RR 0.14 [95% CI 0.06, 0.31]) compared with conventional treatment.

CONCLUSIONS

Acellular dermal matrices appear to be effective at treating capsular contracture after breast augmentation while maintaining a low complication rate. Overall capsular contracture rates are low with the use of ADM. There is a statistically significant difference in efficacy among ADM types. Meta-analysis shows that Strattice is effective at reducing the risk of capsular contracture in breast augmentation patients when compared to conventional treatment. Future research, especially in the form of randomized controlled trials, is needed to further investigate the efficacy of various ADMs in the treatment of capsular contracture.

LEVEL OF EVIDENCE: 4

Modular Bioreactor Design for Directed Tendon/Ligament Tissue Engineering

Functional tissue-engineered tendons and ligaments remain to be prepared in a reproducible and scalable manner. This study evaluates an acellular 3D extracellular matrix (ECM) scaffold for tendon/ligament tissue engineering and their ability to support strain-induced gene regulation associated with the tenogenesis of cultured mesenchymal stromal cells. Preliminary data demonstrate unique gene regulation patterns compared to other scaffold forms, in particular in Wnt signaling. However, the need for a robust bioreactor system that minimizes process variation was also evident. A design control process was used to design and verify the functionality of a novel bioreactor. The system accommodates 3D scaffolds with clinically-relevant sizes, is capable of long-term culture with customizable mechanical strain regimens, incorporates in-line load measurement for continuous monitoring and feedback control, and allows a variety of scaffold configurations through a unique modular grip system. All critical functional specifications were met, including verification of physiological strain levels from 1–10%, frequency levels from 0.2–0.5 Hz, and accurate load measurement up to 50 N, which can be expanded on the basis of load cell capability. The design process serves as a model for establishing statistical functionality and reliability of investigative systems. This work sets the stage for detailed analyses of ECM scaffolds to identify critical differentiation signaling responses and essential matrix composition and cell–matrix interactions.

Reoperative Augmentation Mammoplasty: An Algorithm to Optimize Soft-Tissue Support, Pocket Control, and Smooth Implant Stability with Composite Reverse Inferior Muscle Sling (CRIMS) and its Technical Variations

BACKGROUND

Reoperative augmentation mammoplasty (RAM) is a challenging procedure, with the highest rates of complications and revision. Complications include implant malposition, lateral displacement, bottoming out, and rotation. These deformities can be addressed with various procedures, but the pocket control and stability of the new smooth implant surface may present limitations.

OBJECTIVES

This study revisits a previously described predictable approach in primary breast augmentation and defines a surgical treatment algorithm for RAM technique selection.

METHODS

Between 2017 and 2021, 72 patients (144 breasts) underwent RAM with composite reverse inferior muscle sling (CRIMS) technique and its technical variations (types I-IV). CRIMS technique involves placing a silicone gel implant into the submuscular (SM) pocket with an inferior sling of the pectoralis major muscle based on the dimensions of the implant, in combination with support points/dermal bridge sutures to stabilize the implant and glandular tissue at the lower breast pole (LBP). Reasons for surgery were ptosis (92%), implant and malposition (59.6%). Patients were followed for at least 6 months in 5 cases (6.9%), at least 12 months in 50 cases (69.4%), for at least 36 months in 10 cases (13.8%), and more than 36 months in 7 cases (9.7%) (mean 34 months; range 6-48 months). Patients were evaluated in terms of resolution of symptoms, satisfaction, and complications. Three-dimensional imaging (3DI) obtained from the Divina scanner system was used and followed up for 1 year to evaluate breast position, lower pole stretch (LPS), and intermammary distance (IMD).

RESULTS

Eleven cases of minor complications were observed in 9 patients (12.5%): hypertrophic scarring in 4 (5.5%), wound dehiscence in 4 (5.5%), Baker II/III capsular contracture in 1 (1.3%). SmoothSilk surface silicone implants were used in all cases, with an average volume decrease of 120 cc. Sixty-eight patients (94.4%) were either very satisfied/satisfied with their aesthetic result. Breast images were performed in a group of 65 patients (90.2%), and in 7 breasts (10.7%), localized oil cysts were observed. The value for LPS was 7.87% (p <0.0001) between 10 days and 1 year, with the majority occurring early in the first 3 months, indicating that the LBP/implant remains steady during the last months of follow-up. No cases of fat necrosis/seroma were observed. There were no signs of intra/extracapsular ruptures, capsular contracture. There were 2 cases (3%) of minimal implant displacement and no cases of rotation.

CONCLUSIONS

CRIMS and its variations can be performed successfully in RAM. An algorithmic approach can facilitate the pre- and intraoperative decision-making process and provide the new pocket control and implant stability with acceptable complication rates. Further accurate evaluation is recommended to understand the benefits or disadvantages of CRIMS compared to other RAM techniques.

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 .

Management of Patients with Textured Surface Breast Implants

SUMMARY

The purpose of this special topic article is to present an evidence-based approach and provide recommendations for the management of both asymptomatic and symptomatic patients with textured surface breast implants. There are currently no scientific data to support complete removal of a benign capsule. When unnecessary capsulectomies are performed, the patient is at higher risk for developing postoperative complications. Ultimately, the decision to keep, exchange, or remove breast implants is the patient's decision and the procedure should be performed only by a qualified surgeon.

An Algorithm for the Management of Explantation Surgery

Creating pleasing breast aesthetics after an explantation can be challenging, especially when performed with a total capsulectomy. The necessity of a capsulectomy for a variety of breast issues is not completely agreed on and can increase adverse events, patient morbidity, and cost of the operation and often impairs the final aesthetic result. In this article, an algorithm for the management of explantation patients provides a framework for treatment of the capsule and the breast to optimize outcomes.

Applying Principles of Breast Revision to Managing Aesthetic Patients with Textured Implants

SUMMARY

Textured breast implants have garnered increased attention recently because of their risk of breast implant-associated anaplastic large cell lymphoma (BIA-ALCL), an uncommon and treatable type of T-cell lymphoma. Treatment involves bilateral en bloc capsulectomy, which is curative in the majority of cases. At present, there is no defined management approach for aesthetic patients asymptomatic for BIA-ALCL requesting the removal of their textured implants, particularly as it relates to the management of the capsule. It is unclear if en bloc capsulectomy is necessary in these patients as it is in patients with BIA-ALCL. In the absence of clear guidance on the management of the capsule in asymptomatic patients, the basic principles of breast revision surgery can be applied to these patients.

Revisional Breast Surgery: Are Surgical Plans Changed if the Patient Has a Textured Device?

SUMMARY

The authors reviewed the available evidence on revision surgery following implant-based breast surgery with the aim of investigating whether any difference in the surgical approach should be proposed if the patient has a textured device. They included in their review 31 studies presenting different approaches for revision surgery following implant-based breast surgery (both aesthetic and reconstructive), with a level of evidence ranging from 4 to 5. None of the included studies proposed different surgical approaches for revision surgery in patients carrying textured devices. The authors conclude that no different surgical attitudes in revision surgery following implant-based breast surgery should be adopted if the patient has a textured device according to the available evidence, when a correct approach is performed to face the complication or adverse event, following a thorough preoperative study of the patient with the proper diagnostic tools.

Not All Breast Explants Are Equal: Contemporary Strategies in Breast Explantation Surgery

SUMMARY

Breast implant removal and replacement has been a common secondary breast procedure in the long-term maintenance of breast augmentation, but more recently growing concerns about silicone-related systemic illness, breast implant-associated anaplastic large cell lymphoma (BIA-ALCL), and changing perceptions of aesthetic beauty have seen breast implant removal without replacement become increasingly requested by patients. Explantation can be challenging, especially when performed with a total capsulectomy. Currently, there is no evidence regarding whether a partial or total capsulectomy has any effect on BIA-ALCL risk mitigation in patients that have textured implants without disease. Total capsulectomy with incomplete resection of a mass can contribute to hyperprogression of BIA-ALCL and death. There have also been cases of BIA-ALCL diagnosed years after removal of the textured device and "total capsulectomy." Therefore, the common practice of simple prophylactic capsulectomy in a textured implant to mitigate future disease has not been established and at the current time should be discouraged. In addition, aesthetic outcomes can be quite variable, and patients should have appropriate preoperative counseling regarding the indications and contraindications for explantation, associated risks, financial implications, and postoperative appearance. The authors review salient aspects related to the planning and management of breast implant removal.

Surgical Treatment for Capsular Contracture: A New Paradigm and Algorithm

BACKGROUND

Capsular contracture following breast augmentation is prone to recurrence with conventional surgical therapy. Adding acellular dermal matrix improves results but significantly increases operating time and cost. This study tested a new treatment algorithm that uses acellular dermal matrix selectively to optimize success rates while minimizing its drawbacks.

METHODS

All patients surgically treated by the authors for Baker grade III/IV capsular contracture between 2007 and 2018 were included in this retrospective cohort study. Data were collected on patient, breast augmentation, capsular contracture, and surgical treatment characteristics, in addition to follow-up findings. Treatment success was defined as Baker grade II or better.

RESULTS

One hundred eighty patients underwent 217 surgical treatments for capsular contracture. Conventional treatment was used in 185 cases and acellular dermal matrix in 32. Twenty-six patients were treated for a second occurrence and four were treated for a third. The average follow-up was 2.4 years. Conventional treatment was successful in 72.5 percent of first occurrences, 62.5 percent of second occurrences, and 50.0 percent of third occurrences. Acellular dermal matrix was successful in 96.9 percent of cases. The odds of failure were increased by bilateral capsular contracture (3.9 times) and previous treatment failure (3.5 times). When acellular dermal matrix was used selectively for bilateral capsular contracture or in unilateral cases with a previous treatment failure, the overall treatment success rate improved to 85.6 percent compared with 64.2 percent when this algorithm was not followed (p < 0.001).

CONCLUSION

This study demonstrates that selective acellular dermal matrix use can increase success rate to over 85 percent in the overall treatment of capsular contracture, and to nearly 100 percent in individual cases.

Endoscopic transaxillary prepectoral conversion for submuscular breast implants

Background

During breast augmentation, the transaxillary approach provides the advantage of allowing the mammary prosthesis to be placed through incisions that are remote from the breast itself, thereby reducing the visibility of postoperative scars. For patients experiencing capsular contracture who do not want additional scars, the previous transaxillary scar can be used for site change and implant exchange.

Methods

This study analyzed 17 patients (34 breasts) with submuscular breast implants with grade III-IV capsular contracture who received treatment from 2010 to 2015. The mean age of the patients was 29 years (range, 20–38 years). The inclusion criterion was a pinch test of more than 3 cm at the upper pole of the breast. Previous axillary scars were used to expose the pectoralis fascia, and submuscular breast implants were removed carefully. The dissection underneath the pectoralis fascia was performed with endoscopic assistance, using electrocautery under direct visualization.

Results

The mean follow-up period was 14 months (range, 6–24 months). The entire dissection plane was changed from the submuscular plane to the subfascial plane. Round textured gel implants were used, with a mean implant size of 220 mL (range, 160–300 mL). Two patients developed grade II capsular contracture. There were no cases of malposition or asymmetry. Three patients complained of minor implant palpability. None of the patients required additional surgery.

Conclusions

Endoscopic subfascial conversion may be an effective technique for treating capsular contracture and avoiding scarring of the breast in selected patients.

Pathophysiologic Mechanisms and Current Treatments for Cutaneous Sequelae of Burn Wounds

Burn injuries are a pervasive clinical problem. Extensive thermal trauma can be life-threatening or result in long-lasting complications, generating a significant impact on quality of life for patients as well as a cost burden to the healthcare system. The importance of addressing global or systemic issues such as resuscitation and management of inhalation injuries is not disputed but is beyond the scope of this review, which focuses on cutaneous pathophysiologic mechanisms for current treatments, both in the acute and long-term settings. Pathophysiological mechanisms of burn progression and wound healing are mediated by highly complex cascades of cellular and biochemical events, which become dysregulated in slow-healing wounds such as burns. Burns can result in fibroproliferative scarring, skin contractures, or chronic wounds that take weeks or months to heal. Burn injuries are highly individualized owing to wound-specific differences such as burn depth and surface area, in addition to patient-specific factors including genetics, immune competency, and age. Other extrinsic complications such as microbial infection can complicate wound healing, resulting in prolonged inflammation and delayed re-epithelialization. Although mortality is decreasing with advancements in burn care, morbidity from postburn deformities continues to be a challenge. Optimizing specialized acute care and late burn outcome intervention on a patient-by-patient basis is critical for successful management of burn wounds and the associated pathological scar outcome. Understanding the fundamentals of integument physiology and the cellular processes involved in wound healing is essential for designing effective treatment strategies for burn wound care as well as development of future therapies. Published 2018. Compr Physiol 8:371-405, 2018.

Soft Tissue Adjuncts in Revisionary Aesthetic Breast Surgery

Reconstructive breast surgery is challenging and continually evolving. In the past decade, numerous soft tissue adjuncts, such as acellular dermal matrices (ADMs), have revolutionized breast reconstruction serving as a tool to improve results and minimize the need for revision. The use of ADMs has been widely discussed in primary and secondary breast reconstruction after mastectomy. They have been shown to be an effective and safe option to correct complications; however, there is a relative paucity of literature on their use in revisional surgery after aesthetic breast procedures. The authors queried PubMed for existing literature regarding the use of ADMs in secondary breast surgery. Five case series from an initial search of 278 articles met the inclusion criteria. An overall infection rate of 2% and a complication rate of implant malposition was 0.8% with the use of ADMs. Although the literature is sparse regarding their use in this setting, early reports indicate that they are both safe and efficacious with a reasonable rate of complications.

Evidence-Based Medicine: Breast Augmentation

LEARNING OBJECTIVES

After reading this article, the participant should be able to: 1. Understand the key decisions in patient evaluation for cosmetic breast augmentation. 2. Cite key decisions in preoperative planning. 3. Discuss the risks and complications, and key patient education points in breast augmentation.

SUMMARY

Breast augmentation remains one of the most popular procedures in plastic surgery. The integral information necessary for proper patient selection, preoperative assessment, and surgical approaches are discussed. Current data regarding long term safety and complications are presented to guide the plastic surgeon to an evidence-based approach to the patient seeking breast enhancement to obtain optimal results.

Secondary Breast Augmentation

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Assess common clinical problems in the secondary breast augmentation patient. 2. Describe a treatment plan to correct the most common complications of breast augmentation. 3. Provide surgical and nonsurgical options for managing complications of breast augmentation. 4. Decrease the incidence of future complications through accurate assessment, preoperative planning, and precise surgical technique.

SUMMARY

Breast augmentation has been increasing steadily in popularity over the past three decades. Many of these patients present with secondary problems or complications following their primary breast augmentation. Two of the most common complications are capsular contracture and implant malposition. Familiarity and comfort with the assessment and management of these complications is necessary for all plastic surgeons. An up-to-date understanding of current devices and techniques may decrease the need to manage future complications from the current cohort of breast augmentation patients.

The Use of "Precapsular Space" in Secondary Breast Reconstruction

BACKGROUND

Periprosthetic capsule formation is a physiological phenomenon occurring around breast implants. In case of capsular contracture, several surgical techniques are described; among them, total capsulectomy is considered the gold standard, but it is not free of complications. A more conservative procedure is the use of "precapsular space", leaving intact the preexisting capsule. The method presents minor complications and further advantages over total capsulectomy.

METHOD

From November 2010 to June 2014, we treated 92 postmastecttomy patients who previously underwent implant-based reconstruction. They presented implant malposition (bottoming-out, double bubble deformity, upward migration) and different degrees of capsular contracture. The implant was repositioned in a neoprecapsular pocket. Sixty-eight out of 92 patients presented a follow-up longer than 24 months, and they are included in the present study. They were evaluated with a questionnaire 1 month before surgery, at 6 months and 2 years postoperatively. Moreover, two independent plastic surgeons completed the same questionnaire at 6 months and 2 years after surgery.

RESULTS

Mean follow-up is 29 months. Baker III-IV capsular contracture occurred in 9.5 % of the patients, implant malposition in 2.9 % of the cases and no implant displacement rotation was observed. Patient self-assessment preoperatively and postoperatively (at 2 years) revealed improved cosmetic outcomes (p < 0.01). Surgeon assessment correlated with patient self-assessment.

CONCLUSION

The use of precapsular space, first described for aesthetic augmentation, is a valid alternative to total capsulectomy for the treatment of capsular contracture or implant malposition, even in the reconstructive field.

LEVEL OF EVIDENCE IV

This journal requires that the 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 .

Techniques to Repair Implant Malposition after Breast Augmentation: A Review

BACKGROUND

Implant malposition is a complication of breast augmentation that adversely affects aesthetic outcomes. It is one of the most common reasons for revisionary aesthetic breast surgery yet there is a lack of peer reviewed literature dedicated to the management of this complication.

OBJECTIVES

The purpose of this article was to summarize the malposition literature, review the types and causes of this complication, and evaluate the strengths and weakness of procedures aimed at addressing it.

METHODS

A review of the literature was performed using the PubMed database. Articles describing surgical techniques for correction of implant malposition, as well as outcome data for patients undergoing revision with described techniques, were included. Articles describing revisionary surgery following breast reconstruction were excluded. A series of cases are presented to illustrate techniques discussed.

RESULTS

Search criteria resulted in 763 articles. Title and abstract review followed by application of inclusion and exclusion criteria resulted in a total of 21 clinical studies from 1988 to 2014 that were included in this review. All studies included in this study were of level IV or V evidence.

CONCLUSIONS

Despite the overall low level of evidence in the literature regarding secondary breast augmentation, a thorough understanding of the corrective techniques presented will allow surgeons to make the most informed judgments. Weighing the strengths and weakness of these surgical techniques in the context of each patient will allow surgeons to develop the most appropriate treatment strategy. LEVEL OF EVIDENCE 4: Therapeutic.

Does Implant Insertion with a Funnel Decrease Capsular Contracture? A Preliminary Report

BACKGROUND

Capsular contracture remains a common and dreaded complication of breast augmentation. The etiology of capsular contracture is believed to be multi-factorial, and its causes may include biofilm formation due to implant/pocket contamination with skin flora. It has been shown that insertion funnel use reduces skin contact and potential contamination by 27-fold in a cadaver model. After incorporating the funnel into our surgical protocols, we anecdotally believed we were experiencing fewer capsular contractures in our augmentation practices.

OBJECTIVES

The purpose of this study was to test the hypothesis that capsular contracture related reoperation rates decreased after insertion funnel adoption using data from multiple practices.

METHODS

At seven participating centers, we retrospectively reviewed the surgical records from March 2006 to December 2012 for female patients who had undergone primary breast augmentation with silicone gel implants. Group 1 consisted of consecutive augmentations done without the insertion funnel, and Group 2 consisted of consecutive augmentations done with the insertion funnel. The primary outcome variable was development of grade III or IV capsular contracture that led to reoperation within 12 months.

RESULTS

A total of 1177 breast augmentations met inclusion criteria for Group 1 and 1620 breast augmentations for Group 2. The rate of reoperation due to capsular contracture was higher without use of the insertion funnel (1.49%), compared to Group 2 with funnel use (0.68%), a 54% reduction (P = 0.004).

CONCLUSIONS

The insertion funnel group experienced a statistically significant reduction in the incidence of reoperations performed due to capsular contracture within 12 months of primary breast augmentation.

Nine-Year Core Study Data for Sientra's FDA-Approved Round and Shaped Implants with High-Strength Cohesive Silicone Gel

BACKGROUND

Since approval in March 2012, data on Sientra's (Santa Barbara, CA) silicone gel implants have been updated and published regularly to provide immediate visibility to the continued safety and performance of these devices. The 9 year follow-up data support the previously published data confirming the ongoing safety and efficacy of Sientra silicone gel breast implants.

OBJECTIVES

The authors provide updated 9 year study data for Sientra's round and shaped silicone gel breast implants.

METHODS

The Core Study is an ongoing 10 year study that enrolled 1788 patients with 3506 Sientra implants across four indications (primary augmentation, revision-augmentation, primary reconstruction, and revision-reconstruction). For the safety analysis, Kaplan-Meier risk rates were calculated to evaluate postoperative complications, including all breast implant-related adverse effects. For the effectiveness analyses, results were presented through 8 years as patient satisfaction scores were assessed at even years.

RESULTS

Through 9 years, the overall risk of capsular contracture was 12.6%. Smooth devices (16.6%, 95% CI, 14.2%, 19.5%) had a statistically significantly higher rate of capsular contracture compared to textured devices (8.0%, 95% CI, 6.2%, 10.4%). Out of the 610 reoperations in 477 patients, over half of all reoperations were due to cosmetic reasons (n = 315; 51.6%). Patient satisfaction remains high through 8 years, with 90% of primary augmentation patients indicating their breast implants look natural and feel soft.

CONCLUSIONS

The 9-year follow-up data from the ongoing Core Study of the Sientra portfolio of HSC and HSC+ silicone gel breast implants reaffirm the very strong safety profile as well as continued patient satisfaction.

LEVEL OF EVIDENCE

2 Therapeutic.

Effect of ACL graft material on anterior knee force during simulated in vivo ovine motion applied to the porcine knee: An in vitro examination of force during 2000 cycles

This study determined how anterior cruciate ligament (ACL) reconstruction affected the magnitude and temporal patterns of anterior knee force and internal knee moment during 2000 cycles of simulated gait. Porcine knees were tested using a six degree-of-freedom robot, examining three porcine allograft materials compared with the native ACL. Reconstructions were performed using: (1) bone-patellar tendon-bone allograft (BPTB), (2) reconstructive porcine tissue matrix (RTM), or (3) an RTM-polymer hybrid construct (Hybrid). Forces and moments were measured over the entire gait cycle and contrasted at heel strike, mid stance, toe off, and peak flexion. The Hybrid construct performed the best, as magnitude and temporal changes in both anterior knee force and internal knee moment were not different from the native ACL knee. Conversely, the RTM knees showed greater loss in anterior knee force during 2000 cycles than the native ACL knee at heel strike and toe off, with an average force loss of 46%. BPTB knees performed the least favorably, with significant loss in anterior knee force at all key points and an average force loss of 61%. This is clinically relevant, as increases in post-operative knee laxity are believed to play a role in graft failure and early onset osteoarthritis.