Polyethylene Glycol Fusion Restores Axonal Continuity and Improves Return of Function in a Rat Median Nerve Denervation Model.

BACKGROUND: Polyethylene glycol (PEG) can fuse severed closely-apposed axolemmas and restore axonal continuity. We evaluated the effects of PEG-fusion on functional recovery in a rodent forelimb model of peripheral nerve injury. METHODS: The median nerves of male Lewis rats (n=5 per group) were transected and repaired with standard suture repair (SR), SR with PEG (PEG), or SR with PEG and 1% methylene blue (PEG+MB); a sham surgery group was also included. Proximal stimulation produced compound nerve (CAPS) and muscle (CMAPs) action potentials recorded distally. The contralateral limb of each animal acted as an internal control for grip strength measurements. RESULTS: CAPs and CMAPs immediately returned in all PEG and PEG+MB animals, but not in SR animals. PEG and PEG+MB groups demonstrated earlier return of function by post-operative day (POD) 7 (62.6 ±7.3% and 50.9 ±6.7% of contralateral limb grip strength, respectively) compared to SR group, in which minimal return of function was not measurable until POD 21. At POD 98, the PEG group grip strength recovered to 77.2 ±2.8% while the PEG+MB grip strength recovered to 79.9 ±4.4%, compared to 34.9 ±1.8% recovery in the SR group (p<0.05). The PEG and PEG+MB groups reached 50% of the Sham group grip strength on POD 3.8 and 6.3, respectively, whereas the SR group did not reach 50% grip strength recovery of the Sham group throughout the study period. CONCLUSION: PEG-fusion plus neurorrhaphy with or without methylene blue re-established axonal continuity, shortened recovery time, and augmented functional recovery compared to suture neurorrhaphy alone.

Current Concepts in Lower Extremity Amputation: A Primer for Plastic Surgeons.

LEARNING OBJECTIVES: After studying this article, the participant should be able to: 1. Understand the goals of lower extremity reconstruction and identify clinical scenarios favoring amputation. 2. Understand lower extremity amputation physiology and biomechanics. 3. Review soft-tissue considerations to achieve durable coverage. 4. Appreciate the evolving management of transected nerves. 5. Highlight emerging applications of osseointegration and strategies to improve myoelectric prosthetic control. SUMMARY: Plastic surgeons are well versed in lower extremity reconstruction for traumatic, oncologic, and ischemic causes. Limb amputation is an increasingly sophisticated component of the reconstructive algorithm and is indicated when the residual limb is predicted to be more functional than a salvaged limb. Although plastic surgeons have traditionally focused on limb salvage, they play an increasingly vital role in optimizing outcomes from amputation. This warrants a review of core concepts and an update on emerging reconstructive techniques in amputee care.

A Systematic Review of Muscle Synergies during a Walking Gait to Define Optimal Donor-Recipient Pairings for Lower Extremity Functional Reconstruction.

Functional lower extremity reconstruction primarily aims to restore independent ambulation. We sought to define the synergies recruited during a walking gait to inform donor selection for various motor deficits. With these findings, we discuss the functional neuromuscular components of independent gait with the goal of informing lower extremity reconstruction. Methods: A systematic review was performed using MEDLINE for articles published between January 2000 and December 2020. Search terms included (1) "motor module(s)," "synergy," "motor pattern," or "motor primitive" and (2) "gait," "walking," "ambulation," or "locomotion." Abstracts/full texts were reviewed by two independent reviewers. Results: A total of 38 studies were selected. The average reported number of synergies and variance accounted for was 4.5 ± 0.9 and 88.6% ± 7.7%, respectively. Four motor modules were conserved across nearly all studies. Conclusions: Walking can be reduced to the sequential activation of four motor modules. Activities during the stance phase are critical for both standing stability and forward progression and should be prioritized for reconstruction with the goal of preserving efficient gait. Muscles recruited during swing, except those used for ankle dorsiflexion, are less prone to injury and benefit from greater redundancy, less often necessitating reconstruction. With the emphasis on stability during stance, several synergistic or sometimes even antagonistic tendons can be used to replace their counterparts and restore efficient, independent ambulation. With a finite supply of donor tissues, and in the absence of well-defined clinical outcomes data, this research allows us to effectively prioritize reconstructive goals and maximize patient outcomes.

Vascularized, Denervated Muscle Targets for Treatment of Symptomatic Neuromas in the Upper Extremity: Description of Operative Technique.

Symptomatic neuromas of the upper extremity often cause persistent, debilitating pain that is resistant to medical management. Following upper extremity amputation, painful neuromas may disrupt rehabilitation efforts and pose a barrier to prosthetic use. Several surgical approaches have been attempted to treat neuromas, each of which suffers from limitations. We have developed a novel technique, the vascularized, denervated muscle target, that offers a compelling new option for primary prevention and secondary treatment of symptomatic neuromas of the upper extremity. Here, we provide a detailed description of our surgical technique as it is applied to neuromas of the upper extremity.

Utility of Viscoelastic Tests to Predict Flap Thrombosis: A Systematic Review.

BACKGROUND: Flap thrombosis is a rare but devastating complication in microsurgery. Preoperative identification of patients at increased risk for microvascular thrombosis remains challenging. Viscoelastic testing (VET) provides a comprehensive evaluation of the clotting process and can effectively identify hypercoagulability. However, the utility of VET in microvascular reconstruction remains unclear. METHODS: A systematic review of the association between VET and pedicle thrombosis and free flap loss was performed in accordance with Preferred Reporting Items for Systematic Reviews (PRISMA) guidelines. Identified studies were reviewed independently by two authors for pertinent data. RESULTS: Six studies met inclusion criteria. Heterogenous study design and outcome reporting complicated direct comparisons and precluded a formal meta-analysis. Four studies found a statistically significant relationship between VET results and flap thrombosis or flap loss. The maximum clot strength and the fibrinogen-to-platelet ratio (FPR) were key viscoelastic parameters in these studies, both representing a measure of maximal clot strength. Specifically, an elevated FPR (>42%) generated a sensitivity and specificity for flap loss ranging from 57% to 75% and 60% to 82%, respectively. Notably, the negative predictive value for flap failure with a normal preoperative FPR was greater than 90% in all studies reporting a correlation. The remaining two studies reported no predictive value for VET with respect to flap failure or pedicle thrombosis. CONCLUSION: The results of this review suggest that VET, particularly parameters relating to clot strength, may help clinicians identify patients at risk for flap thrombosis. However, uncontrolled and heterogenous reporting limit definitive conclusions, and high-quality diagnostic studies are needed to better determine the clinical utility of viscoelastic testing for free flap patients.

The Effects of a Porcine Extracellular Matrix Nerve Wrap as an Adjunct to Primary Epineurial Repair.

PURPOSE: Outcomes after end-to-end epineural suture repair remain poor. Nerve wraps have been advocated to improve regeneration across repair sites by potentially reducing axonal escape and scar ingrowth; however, limited evidence currently exists to support their use. METHODS: Forty Lewis rats underwent median nerve division and immediate repair. Half were repaired with epineural suturing alone, and the others underwent epineural suture repair with the addition of a nerve wrap. Motor recovery was measured using weekly grip strength and nerve conduction testing for 15 weeks. Histomorphometric analyses were performed to assess intraneural collagen deposition, cellular infiltration, and axonal organization at the repair site, as well as axonal regeneration and neuromuscular junction reinnervation distal to the repair site. RESULTS: The wrapped group demonstrated significantly less intraneural collagen deposition at 5 weeks. Axonal histomorphometry, cellular infiltration, neuromuscular junction reinnervation, and functional recovery did not differ between groups. CONCLUSIONS: Nerve wraps reduced collagen deposition within the coaptation; however, no differences were observed in axonal regeneration, neuromuscular junction reinnervation, or functional recovery. CLINICAL RELEVANCE: These findings suggest that extracellular matrix nerve wraps can attenuate scar deposition at the repair site. Any benefits that may exist with regards to axonal regeneration and functional recovery were not detected in our model.

Donor-site Morbidity of Medial and Lateral Thigh-based Flaps: A Comparative Study.

BACKGROUND: Free and pedicled medial and lateral thigh-based flaps are common reconstructive procedures. However, there have been no comparative studies of morbidity between medial and lateral donor sites. METHODS: We conducted an Enterprise Data Warehouse-based review of all the senior authors' (R.D.G., G.A.D., and M.S.A.) thigh-based free and pedicled flaps. Patient demographic data, donor-site complications, drain duration, and number of postoperative visits were collected and compared. Complications were also compared between fasciocutaneous flaps and muscle or myocutaneous flaps, and skin grafted donor sites. RESULTS: We analyzed 352 flap donor sites, with 155 medial and 197 lateral. Two hundred seventeen (217) flaps were pedicled. Flap types included 127 gracilis, 27 rectus femoris, 134 anterolateral thigh, and 36 vastus lateralis-only flaps. There were no significant differences in complications between medial (17.4%) and lateral thigh (21.3%) donor sites, although lateral thigh flaps had a mean of 1 additional postoperative visit. Rates of wound dehiscence/healing issues were significantly higher in both gracilis myocutaneous flaps (25.9%) and flaps requiring a skin grafted donor site (31.2%). Postoperative therapeutic anticoagulation was the only significant risk factor for a donor-site complication. Flap complications resulted in increased drain duration and postoperative office visits. CONCLUSIONS: Donor-site morbidity is similar in both lateral and medial thigh-based flaps. The inclusion of muscle in the flap from either donor site does not seem to increase complications, but the inclusion of a skin paddle with gracilis muscle, or a skin grafted lateral thigh donor site, results in increased wound healing complications.

Evaluating the Rule of 10s in Cleft Lip Repair: Do Data Support Dogma?

BACKGROUND: Cleft lip represents one of the most common birth defects in the world. Although the timing of cleft lip repair is contingent on a number of factors, the "rule of 10s" remains a frequently quoted safety benchmark. Initially reported by Wilhelmsen and Musgrave in 1966 and modified by Millard in 1976, this rule referred to performing surgery once patients had reached cutoffs in weight, hemoglobin, and age/leukocyte count. Despite significant advances in both surgical and anesthetic technique, the oft-quoted "rule of 10s" has not been systematically investigated since its inception. METHODS: Patients who underwent primary cleft lip repair were identified from the National Surgical Quality Improvement Program Pediatric database. Multivariate logistic regression models were used to determine the independent effect of each rule of 10 metric or violation of the rule of 10s as a whole on postoperative complications, and to determine independent risk factors for complications in cleft lip surgery. RESULTS: One thousand three hundred thirteen patients met inclusion criteria, with a 3.6 percent complication rate. Of the included patients, 151 (11.5 percent) violated at least one facet of the rule of 10s. Other than patient weight, neither the rule of 10s nor any individual metric was significantly predictive of postoperative complications. CONCLUSIONS: Since its introduction nearly a half century ago, the risks associated with performing surgery in patients who violate the rule of 10s has undergone dramatic reductions. This analysis highlights the need to continually validate and evaluate dogma as the field continues to advance. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, III.

Predictors of 30-day readmission after mastectomy: A multi-institutional analysis of 21,271 patients.

BACKGROUND: Recent healthcare legislation has made unplanned hospital readmission an important metric of health care quality, and current efforts center on reducing this complication in order to avoid fiduciary penalties. OBJECTIVE: There is currently a paucity of data delineating risk factors for readmission following mastectomy. To this end, we sought to develop a predictive model of unplanned readmissions following mastectomy. METHODS: The 2011 and 2012 National Surgical Quality Improvement Program (NSQIP) datasets were retrospectively queried to identify patients who underwent mastectomy. Multivariate logistic regression modeling was used to identify risk factors for readmission. RESULTS: Of 21,271 patients meeting inclusion criteria, 1,190 (5.59%) were readmitted. The most commonly cited reasons for readmission included surgical site complications (32.85%), infection not localized to the surgical site (2.72%), and venous thromboembolism (4.39%). Independent predictors of readmission included BMI, active smoking status, and skin-sparing mastectomy. Significantly, concurrent breast reconstruction and bilateral mastectomy were not independent predictors of readmission. CONCLUSIONS: This is the first study of readmission rates after mastectomy. Awareness of specific risk factors for readmission, particularly those that are modifiable, may serve to identify and manage high risk patients, aid in the development of pre- and postoperative clinical care guidelines, and ultimately improve patient care.

Is There a Safe Lipoaspirate Volume? A Risk Assessment Model of Liposuction Volume as a Function of Body Mass Index.

BACKGROUND: No concrete data exist to support a specific volume at which liposuction becomes unsafe; surgeons rely on their own estimates, professional organization advisories, or institutional or government-imposed restrictions. This study represents the first attempt to quantify the comprehensive risk associated with varying liposuction volumes and its interaction with body mass index. METHODS: Suction-assisted lipectomies were identified from the Tracking Operations and Outcomes for Plastic Surgeons database. Multivariate regression models incorporating the interaction between liposuction volume and body mass index were used to assess the influence of liposuction volume on complications and to develop a tool that returns a single adjusted odds ratio for any combination of body mass index and liposuction volume. Recursive partitioning was used to determine whether exceeding a threshold in liposuction volume per body mass index unit significantly increased complications. RESULTS: Sixty-nine of 4534 patients (1.5 percent) meeting inclusion criteria experienced a postoperative complication. Liposuction volume and body mass index were significant independent risk factors for complications. With progressively higher volumes, increasing body mass index reduced risk (OR, 0.99; 95 percent CI, 0.98 to 0.99; p = 0.007). Liposuction volumes in excess of 100 ml per unit of body mass index were an independent predictor of complications (OR, 4.58; 95 percent CI, 2.60 to 8.05; p < 0.001). CONCLUSIONS: Liposuction by board-certified plastic surgeons is safe, with a low risk of life-threatening complications. Traditional liposuction volume thresholds do not accurately convey individualized risk. The authors' risk assessment model demonstrates that volumes in excess of 100 ml per unit of body mass index confer an increased risk of complications. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Flap Reconstruction for Esophageal Perforation Complicating Anterior Cervical Spinal Fusion: An 18-year Experience.

BACKGROUND: Esophageal injury following anterior cervical discectomy and fusion (ACDF) poses a significant reconstructive challenge. Buttressing flap repairs have proven beneficial; however, there remains a paucity of evidence to guide optimal flap selection. METHODS: A retrospective chart review was performed for patients who presented to the senior author with esophageal perforations after ACDF from 1995 until present. Demographic, clinical, and postoperative details were collected. Outcomes of omental flap reconstructions were compared against other flap reconstructions. RESULTS: A total of 13 flap reconstructions were performed in 11 patients with the following distribution: 7 free omental, 1 anterolateral thigh, 1 osteomuscular fibula, 2 radial forearm, and 2 pedicled pectoralis flaps. Patients receiving omental flap reconstructions demonstrated a significantly faster resolution of leak on contrast swallow imaging and earlier return to oral feeding compared with all other flap reconstructions (22.5 versus 268 days, respectively; P < 0.05). This relationship remained evident even when calculations excluded an outlying patient from the nonomental cohort (22.5 versus 111 days, respectively; P < 0.05). Length of hospital stay, complications, and success rates were also more favorable in the omental cohort but failed to reach statistical significance. CONCLUSIONS: Esophageal perforation after ACDF is an uncommon but devastating complication. The use of free omentum flap reconstruction is associated with a more rapid functional recovery and may prove beneficial in the management of these challenging cases.

Body mass index as a continuous predictor of outcomes after expander-implant breast reconstruction.

BACKGROUND: Studies show that obesity is a risk factor for complications after expander/implant breast reconstructions. However, reports vary on the precise threshold of body mass index (BMI) as a predictor of heightened risk. We endeavored to link BMI as a continuous variable to overall complications in a single-surgeon series of expander-implant reconstructions. METHODS: From 399 patients undergoing expander-implant reconstruction, 551 breasts were stratified to normal weight, overweight, and obese groups for analysis and comparison with previous studies. Logistic regression was performed to predict changes to risk profile per increment of BMI. RESULTS: Complication rates for obese and overweight patients were significantly greater than for normal weight patients, that is, 21.1% and 24.0% versus 10.4%, respectively (P < 0.005). A unit increase in BMI predicted a 5.9% increase in the odds of a complication occurring, and 7.9% increase in the odds of reconstruction ending in failure. CONCLUSIONS: By expanding the analysis of BMI to include patients who do not meet the traditional definition of obesity (BMI ≥ 30 kg/m), we demonstrated that simply overweight patients (25 ≤ BMI < 30 kg/m) had an elevated complication rate. Moreover, through regression analysis, we established that BMI as a continuous variable predicts outcomes from expander-based breast reconstruction.

The impact of body mass index on reduction mammaplasty: a multicenter analysis of 2492 patients.

BACKGROUND: Reduction mammaplasty is commonly performed in women who are considered obese by the body mass index (BMI) classification of the World Health Organization. OBJECTIVES: The authors compare complication rates among breast reduction patients, stratified by BMI, across multiple institutions. METHODS: A retrospective analysis was performed of all reduction mammaplasties in the database of the National Surgical Quality Improvement Program for 2006 through 2010. Demographic, comorbidity, and BMI data were collected. Data on medical and surgical complications, reoperation, and mortality were collected through 30 days postsurgery. RESULTS: Of 2492 patients, 55% were considered obese (BMI >30). The overall rate of surgical complications was 4.0%, increasing from 2.4% for BMI <25 to 7.1% for BMI >45 (P = .006), with an adjusted odds ratio of 2.97 for BMI >45 versus BMI <25. The most common surgical complication was superficial surgical site infection; it was found in 2.9% of patients, increasing from 2.1% for BMI <25 to 5.1% for BMI >45 (P = .03). The medical complication rate was 0.6%, and the reoperation rate was 2.1%. There were no deaths. A maximal point analysis showed that BMI ≥39 was associated with a significantly higher complication rate, with an odds ratio of 2.38. CONCLUSIONS: Reduction mammaplasty is a safe surgical procedure, even when performed on obese patients. However, patients with higher BMI have a greater risk of surgical site complications. This risk should be discussed preoperatively with obese patients.

The Relationship between Preoperative Wound Classification and Postoperative Infection: A Multi-Institutional Analysis of 15,289 Patients.

BACKGROUND: Despite advances in surgical techniques, sterile protocols, and perioperative antibiotic regimens, surgical site infections (SSIs) remain a significant problem. We investigated the relationship between wound classification (i.e., clean, clean/contaminated, contaminated, dirty) and SSI rates in plastic surgery. METHODS: We performed a retrospective review of a multi-institutional, surgical outcomes database for all patients undergoing plastic surgery procedures from 2006-2010. Patient demographics, wound classification, and 30-day outcomes were recorded and analyzed by multivariate logistic regression. RESULTS: A total of 15,289 plastic surgery cases were analyzed. The overall SSI rate was 3.00%, with superficial SSIs occurring at comparable rates across wound classes. There were similar rates of deep SSIs in the clean and clean/contaminated groups (0.64%), while rates reached over 2% in contaminated and dirty cases. Organ/space SSIs occurred in less than 1% of each wound classification. Contaminated and dirty cases were at an increased risk for deep SSIs (odds ratios, 2.81 and 2.74, respectively); however, wound classification did not appear to be a significant predictor of superficial or organ/space SSIs. Clean/contaminated, contaminated, and dirty cases were at increased risk for a postoperative complication, and contaminated and dirty cases also had higher odds of reoperation and 30-day mortality. CONCLUSIONS: Analyzing a multi-center database, we found that wound classification was a significant predictor of overall complications, reoperation, and mortality, but not an adequate predictor of surgical site infections. When comparing infections for a given wound classification, plastic surgery had lower overall rates than the surgical population at large.

The differential effect of BMI on prosthetic versus autogenous breast reconstruction: a multivariate analysis of 12,986 patients.

BACKGROUND: The comparative safety of breast reconstruction in obese patients remains to be clearly defined. This study utilized multi-institutional data to characterize the effect of body mass index (BMI) on breast reconstruction outcomes. METHODS: Utilizing Current Procedural Terminology (CPT) codes, patients undergoing tissue expander, pedicled transverse rectus abdominis myocutaneous (TRAM) flap, latissimus dorsi flap, and free flap breast reconstruction were identified in the National Surgical Quality Improvement Program (NSQIP) database. Patients were stratified as obese (BMI ≥ 30) and non-obese (BMI < 30). Overall postoperative morbidity, flap complications, non-flap complications, and reoperation rates were compared among the groups. RESULTS: Of 12,986 patients who underwent breast reconstruction, 3636 (28.0%) were obese. Overall morbidity was significantly elevated in obese patients across all forms of reconstruction (p < 0.05). BMI was correlated with increased surgical complications for tissue expander, pedicled TRAM, and free flap reconstructions (OR = 1.09, OR = 1.05, OR = 1.10, respectively; p < 0.05). Medical complications were higher in obese patients undergoing tissue expander and pedicled TRAM reconstructions (p = 0.001 and p < 0.001), but no significant difference was observed in latissimus and free flap reconstruction patients. Compared with obese tissue expander recipients, obese patients reconstructed using autologous tissue had higher rates of reoperations (12.8% versus 9.1%), overall morbidity (18.0% versus 9.5%), surgical (12.7% versus 8.3%), and medical complications (9.0% versus 2.2%). CONCLUSIONS: The NSQIP database allows for evaluation and comparison of reconstructive outcomes in the obese population. Increased BMI was associated with higher morbidity in autologous reconstruction than tissue expander reconstruction. Among autologous procedures, latissimus flaps experienced the lowest captured 30 day morbidity.

Risk profiles and outcomes of total laparoscopic hysterectomy compared with laparoscopically assisted vaginal hysterectomy.

OBJECTIVE: With the increasing rates of minimally invasive hysterectomy procedures serving as impetus, the aim of this study was to analyze the 30-day risk profiles associated with total laparoscopic hysterectomy and laparoscopically assisted vaginal hysterectomy (LAVH). METHODS: The American College of Surgeons National Surgical Quality Improvement Program database was queried for patients who underwent a total laparoscopic hysterectomy or LAVH operation between 2006 and 2010. Patient demographics and 30-day complication rates were calculated. Multivariable regression analyses were used to study the effect of hysterectomy approach on outcomes. RESULTS: A total of 6,190 patients underwent laparoscopic hysterectomy, with 66.3% receiving LAVH and 33.7% receiving a total laparoscopic hysterectomy. The patient cohorts were well-matched. Although total laparoscopic hysterectomy procedures were significantly longer than LAVH operations (2.66 hours compared with 2.20 hours; P<.001), there was no difference in overall morbidity or reoperation rates between the LAVH and total laparoscopic hysterectomy populations (7.05% compared with 6.3% for overall morbidity; 1.3% compared with 1.7% for reoperation). Regression analyses revealed that surgical approach was not a significant predictor of overall postoperative morbidity or reoperation in minimally invasive hysterectomy patients. Additionally, obesity did not demonstrate a significant association with morbidity or reoperation rates; however, operative time was found to be a significant predictor of reoperation (odds ratio 1.23, 95% confidence interval 1.07-1.42). CONCLUSION: Laparoscopic hysterectomy is well-tolerated with total laparoscopic hysterectomy and LAVH, yielding comparable rates of postoperative morbidity and reoperation. On average, LAVH procedures were 28 minutes faster than total laparoscopic hysterectomy. Additionally, increasing body mass index was not associated with higher rates of morbidity. LEVEL OF EVIDENCE: II.

A predictive model of risk and outcomes in tissue expander reconstruction: a multivariate analysis of 9786 patients.

Outcomes of tissue expander breast reconstruction show variability based on presurgical risk factors. Few comprehensive, multi-institutional risk analyses exist. Patients who underwent tissue expander reconstruction were identified in a multi-institutional registry that spans over 240 institutions with over 200 variables per patient. Bivariate analysis of preoperative variables was performed across outcomes. Multivariate logistic regression was used to adjust for confounders and identify risk factors for complications. In 9786 total tissue expander patients, 526 (5.38%) patients experienced one or more complications. Wound infection and reoperations occurred in 3.45% and 6.76% of patients, respectively. Body mass index (BMI) was found to be a significant independent risk factor for overall morbidity, reoperation, prosthesis failure, and wound infection. Overweight, obese, and morbidly obese patients were at 1.7-, 2.6-, and 5.1-times greater risk of morbidity, respectively (p < 0.001 for all). Reconstructive timing, combined surgical procedures, and neoadjuvant chemotherapy were not found to be significant predictors of morbidity. The odds of developing complications were 1.5- and 1.3-times greater in smokers and patients over the age of 50, respectively (p = 0.001 and p = 0.015). For each additional hour of surgery, the odds of morbidity increased 1.26-times (p < 0.001). Precise risk profiles garnered from multi-institutional studies can help improve patient selection and education. Overall, tissue expander reconstruction was found to be safe, with relatively few complications. Operative time, BMI, and smoking were consistently found to be independent risk factors for postoperative morbidity.