Microsurgical Reconstruction in an Orthopedic Hospital: Indications and Outcomes in Adults

Abstract

Objective Advances in reconstructive microsurgery in orthopedic surgery provided better functional and aesthetic results and avoided many indications for amputation. In high-volume trauma and orthopedic hospitals, microsurgical reconstruction is essential to reduce costs and complications for these complex orthopedic defects. We describe a microsurgical approach to traumatic wounds, tumor resection, bone defects, and free muscle transfer, performed by an orthopedic microsurgery unit. The objective of the present study was to evaluate predictor factors for outcomes of microsurgical flaps for limb reconstruction, and to provide a descriptive analysis of microsurgical flaps for orthopedic indications.

Methods Cross-sectional prospective study that included all consecutive cases of microsurgical flaps for orthopedic indications from 2014 to 2020. Data were collected from personal medical history, intraoperative microsurgical procedure, and laboratory blood tests. Complications and free-flap outcomes were studied in a descriptive and statistical analysis.

Results We evaluated 171 flaps in 168 patients; the indications were traumatic in 66% of the patients. Type III complications of the Clavien-Dindo Classification were observed in 51 flaps. The overall success rate of the microsurgical flaps was 88.3%. In the multivariate analysis, the risk factors for complications were ischemia time ≥ 2 hours (p = 0.032) and obesity (p = 0.007). Partial flap loss was more common in patients with thrombocytosis in the preoperative platelet count (p = 0.001).

Conclusion The independent risk factors for complications of microsurgical flaps for limb reconstruction are obesity and flap ischemia time ≥ 2 hours, and presence of thrombocytosis is a risk factor for partial flap loss.

 

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Keywords

free tissue flaps - trauma - microsurgery - orthopedic procedures - tissue transplantation

Introduction

Microsurgical flaps are established as one important tool in reconstructing traumatic complex defects of the limbs. In some cases, this tool can provide better aesthetic and functional results, as an immediate and definitive coverage, following an old concept of fix and flap[1] or a newer concept of reconstructive elevator.[2]

The treatment of complex lesions of the musculoskeletal system has evolved to a combination of orthopedic techniques allied with free-flap transfer, described as orthoplastic reconstruction in traumatic cases.[3] [4] Most of these complex cases need to be transferred to a referral hospital, thus prolonging hospitalization period and increasing costs for the public health system.[5]

Microsurgical flaps for limb reconstruction are either functional or an attempt to spare limb surgery, so they are usually performed under circumstances that can be less than ideal to reduce complications. Although patients with complex injuries of the limbs are referred to orthopedic centers, microsurgical flaps are usually performed by plastic surgery teams. We describe the experience of an orthopedic microsurgery group providing combined early treatment to reduce healthcare costs and achieve better functional results. The objective of the present study is to describe the role of reconstructive microsurgery in an orthopedic department with indications and results of free flaps, with combined treatment for orthopedic injuries, through descriptive analysis of the cases and evaluation of predictive factors that influence the incidence of complications of microsurgical flaps in the musculoskeletal apparatus.

 

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Patients and Methods

A prospective observational study with consecutive inclusion of all patients submitted to microsurgical flaps in an orthopedic department. The main indications were traumatic wounds with exposure of bone and/or of neurovascular bundle that could not be covered with pedicle flaps or skin grafts, long bone defects > 6 cm, and free functional muscular transfers for upper limbs. The Exclusion criteria were patients < 18 years old and insufficient postoperative data at follow-up. The Ethical and Scientific Committee approved the present work (CAAE no. 42679515.2.0000.0068). Informed consent was obtained from all individual participants included in the present study, and the study was performed in accordance with the Declaration of Helsinki.

The database included patient demographics (age, gender, and comorbidities) and laboratory analysis of hemoglobin and platelet count in blood levels. The following intraoperative data were recorded: type of flap, recipient vessels, type of arterial anastomosis, number of venous anastomoses, intraoperative ischemia time of free flap (time elapsed between the section of the pedicle in the donor area and the release of claps of the artery and at least one vein with flap perfusion), and participation of the training resident performing microanastomosis.

Complications included were (type III of the Clavien-Dindo classification):[6] deep infection that required surgical debridement, hematoma that required surgical drainage, dehiscence, take-back flap, amputation, and partial or total flap loss.

 

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Statistical Analysis

Statistical analyses were performed in IBM SPSS Statistics for Windows, version 20.0 (IBM Corp., Armonk, NY, USA). Anemia (moderate or severe) was defined as hemoglobin < 11 g/dL (World Health Organization [WHO])[7] and thrombocytosis as platelets count ≥ 450 × 10⁹/L).[8] Obesity was defined as presence of body mass index (BMI) ≥ 30 kg/m² (WHO). Traumatic cases, excluding 6 cases of toe-to-hand transfer, were divided into chronic (operated > 21 days after the traumatic event) and acute (operated within ≤ 21 days after the trauma). Next, these groups were subdivided into 2 groups: ≤ 7 days after the trauma or > 7 days. Qualitative data were analyzed by the Pearson chi-squared test or by the Fisher exact test when the frequency was lower than expected. The Mann-Whitney U-test was used for quantitative nonparametric data. Ischemia time cutoff was determined by the Youden index, in receiver operating characteristic (ROC) curve. Binary logistic regression was then conducted on the variables with p<0.20 in the univariate analysis and included one independent variable in the logistic regression for each 10 cases of occurrence of complication. The backward algorithm was used.

 

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Results

A total of 171 microsurgical flaps in 166 patients, performed between 2014 and 2020, were studied ([Table 1]). The mean age was 35.2 years old (19 to 69 years old, standard deviation [SD]: 11.3). The most common indication for microsurgical reconstruction was traumatic lesion in 109 patients ([Fig. 1]); among them, there were 6 cases of toe-to-hand and 103 cases of limb reconstruction, with 50 patients treated within 21 days after the traumatic event (19 patients within 7 days after the traumatic event) and 53 patients after 21 days, or chronic cases ([Table 2]).

Table 1

Gender	Number of flaps (%)
Male	130 (76%)
Female	41 (24%)
Indications
Trauma	109 (63.7%)
Brachial plexus lesion	42 (24.6%)
Tumor	10 (5.8%)
Burn scar	6 (3.5%)
Others	4 (2.4%)
Comorbidities (isolated or associated)
Obesity	34 (19.9%)
Mean obesity BMI = 33.0 kg / m2
Mean general group BMI = 26.13 kg / m2
Smokers	16 (9.3%)
Systemic hypertension	11 (6.4%)
Diabetes mellitus	9 (5.3%)
Other	5 (3.0%)
171 free flaps in 166 patients

Table 2

Type of flap	Number of flaps (%)
ALT	47 (45.6%)
Latissimus dorsi	25 (24.3%)
Vascularized fibular flap	14 (13.6%)
Lateral arm	8 (7.8%)
Parascapular	2 (1.9%)
Others	7(6.8%)
Type of arterial anastomosis
End-to-side	73 (70.9%)
End-to-end	30 (29.1%)
Number of venous anastomoses
1 vein	58 (56.3%)
2 veins	45 (43.7%)
Time of free flap from trauma
< 21 days	50 (48.5%)
> 21 days	53 (51.5%)
103 free flaps in traumatic cases

Fig. 1 Male, 67 years old, traumatic complex wound in the forearm, submitted to ALT flap, proximal row carpectomy and external fixation of the wrist.

The age of the patient did not influence the presence of complications (p = 0.996).

Fifty patients had anemia in the preoperative evaluation. The average hemoglobin values were 13.1 g/dL. Postoperatively, 90 patients (52.6%) had anemia, and the average hemoglobin level was 10.4 g/dL (SD = 1.8 g/dL). Analysis of platelet count showed that 19 patients had preoperative thrombocytosis, with 307 × 10⁹/L in average (SD = 146 × 10⁹/L).

The most common flap was the anterolateral thigh (ALT) flap in 31% of the cases ([Figs. 2] and [3]). Intraoperative data are described in [Table 3].

Table 3

Type of flap	Number of flaps (%)
ALT	53 (31%)
Free gracilis	45 (26.3%)
Vascularized fibular flap	21 (12.3%)
Latissimus dorsi	26 (15.2%)
Lateral arm	10 (5.8%)
Others	16 (9.4%)
Type of arterial anastomosis
End-to-side	88 (51.5%)
End-to-end	83 (48.5%)
Number of venous anastomosis
1 vein	101 (59.1%)
2 veins	70 (40.9%)
171 free flaps in 166 patients

Fig. 2 Type of microsurgical flap according to the donor area.

Fig. 3 Female, 32 years old, chronic traumatic complex defect of tibia, submitted to bone shortening and intramedullary internal fixation and ALT flap.

A vein graft was necessary for anastomosis in nine patients. The comitantes or deep venous system was chosen in 77.2% of the cases. The mean ischemia time was 124.49 minutes (SD: 45.2 minutes). Residents performed at least 1 arterial or venous anastomosis (or both) in 141 flaps (82.5%).

Clavien-Dindo type III complications were observed in 51 flaps, which are described in [Fig. 4]. In four patients, a second free flap was required, and in one of these patients a third free flap was performed ([Fig. 5]).

Fig. 4 Number of cases of microsurgical flaps according to the presence of complications.

Fig. 5 Male patient, 28 years old, submitted to oncologic resection and ALT flap. Complication of partial flap loss, treated with negative pressure wound therapy and skin graft.

Increased ischemia time had a statistically significant association with complication rates. The area under the ROC curve ([Fig. 6]) was 0.617 and the cutoff point was determined based on the Youden criteria of 2 hours (71% sensitivity and 59% specificity). Based on this cutoff point, the time of ischemia was categorized into 2 groups: > 2 hours and ≤ 2 hours.

Fig. 6 ROC curve characteristics with analysis of ischemia time related to complications.

[Table 4] summarizes the univariate and multivariate analyses of the risk factors for complications. Ischemia > 2 hours and obesity remained as independent risk factors. Patients with complications had longer hospitalization days (p < 0.001). Residents performing the anastomosis did not influence the incidence of complications (p = 0.982), including when performing end-to-side anastomosis (p = 0.217). Excluding obesity, the presence of other comorbidities did not influence the incidence of complications (p = 0.982), including patients with diabetes mellitus (p = 0.813).

Table 4

	Univariate	Multivariate
	p-value	OR	95%CI	p-value
Ischemia time > 2 hours	0.007	2.2	1.1–4.6	0.032
Vein graft	0.014	3.8	1.1–16.7	0.08
ETS artery	0.112	1.8	0.9–3.8	0.12
BMI ≥ 30 kg/m2	0.004	2.5	1.1–5.7	0.007

For partial flap loss to occur, the presence of thrombocytosis (p = 0.003), preoperative anemia (p = 0.013), and end-to-side (ETS) arterial anastomosis (p = 0.009) were statistically significant in the univariate analysis; thrombocytosis was the only independent risk factor in the multivariate analysis (0.001). The risk factor for total flap loss was the indication of vein graft for anastomosis (p = 0.012).

The indication of take-back flap was associated with a higher incidence of total flap loss (p < 0.001) and the independent risk factor for take-back flap was obesity in multivariate analysis. The statistical analysis is summarized in [Table 5].

Table 5

	Univariate	Multivariate
	p-value	OR	95%CI	p-value
Ischemia time > 2 hours	0.004	2.3	1.0–6.4	0.07
Resident performing anastomosis	0.093	3.5	0.8–16.6	0.11
One venous anastomosis	0.323	1.4	0.6–3.3	0.44
Vein graft	0.005	4.2	10.9–18.7	0.06
BMI ≥ 30 kg/m2	0.031	2.7	1.0–6.9	0.04

In the group of traumatic cases, patients submitted to microsurgical reconstruction > 7 days after the traumatic event had a higher rate of complications (p = 0.043) and no difference of flap survival (p = 0.64). No difference between chronic cases (operated > 21 days after the trauma) and acute cases for complications and survival rate was observed (p = 0.3 and p = 0.93, respectively).

The success rate of the microsurgical flaps was 88.3%, with a 3% amputation rate.

 

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Discussion

Microsurgical reconstruction in orthopedic surgery demands specialized technical support, high-cost materials, the involvement of multiprofessional health workers, and requires long hospitalization periods.[9] Pohlenz et al.[10] suggest that the success rate is due to experience and postoperative support in a high-volume hospital. In our study, as well as in the literature,[11] [12] [13] we observed an increased incidence of male young patients with traumatic injuries, especially due to traffic accidents (53% of the cases). In these cases, it is important to perform a combined treatment with bone stabilization or reconstruction with skin coverage, with simultaneous teams. To reduce the number of surgeries, infection rates, and hospitalization time,[14] it is important to establish reconstructive microsurgery centers in orthopedic hospitals.

We did not observe influence of advanced age on complications, as evidenced by other papers.[15] [16] In our orthopedic hospital, free flaps in elderly are not common, since oncologic reconstruction is less common than trauma and only 6 patients > 60 years old were operated on with no occurrence of complications. In selected patients requiring microsurgical flap for limb salvage, age should not be a determinant for absolute contraindication[17]; the success rates in older patients can be similar to those in young patients through adequate preoperative planning and clinical stabilization of the patient.

When we analyzed the presence of comorbidities, obesity was an independent risk factor for complications, including take-back flap, a result similar to that obtained by Cleveland et al.,[18] who observed an increased incidence of total flap loss. Obese patients have a greater association with cardiovascular diseases and metabolic disorders, as well as inherent difficulties for anesthesia, such as control of drug delivery and greater volumes administered. From the surgical point of view, these patients imply greater technical difficulty due to increased blood loss and depth of the structures.

Presence of anemia did not influence the results in our study. Hill et al.[19] demonstrate an increase in total flap loss and vascular thrombosis in patients with anemia. In situations of hypotension and hypovolemia, peripheral vasoconstriction occurs, which causes reduced flow that is harmful to microsurgical flaps. Therefore, we suggest maintaining hemoglobin values > 10 g/dL, which justifies the high indication for blood transfusion in our series (60% of the patients).

Performing single or two-venous anastomosis to drain free flap did not influence the incidence of complications in our study; however, an increase in take-back flap was observed in patients with only 1 venous anastomosis (22 versus 15% with two-venous anastomoses), but it was not statistically significant. Ross et al.[20] observed better outcomes with free-flap reconstruction when two-venous anastomosis was performed, and Dornseifer et al.[21] described a higher incidence of take-back flap with single-venous anastomoses. As venous thrombosis is the most common vascular complication in microsurgical flaps, we suggest that when the flap has more than one venous system for drainage and when the operative time is not long, two-venous anastomoses should be performed.

When comparing the type of arterial anastomoses, we observed that end-to-side (ETS) anastomosis had a higher incidence of partial flap loss in the univariate analysis. Tsai et al.[22] concluded that end-to-end and ETS anastomoses have similar flap survival rates. We recommend ETS anastomosis to preserve the main arteries of the limbs and when anatomical variations are expected, such as vessel size discrepancy,[23] [24] although ETS anastomosis requires greater technical skill and probably a higher learning curve in training hospitals with residency in microsurgery.

Our orthoplastic unit has a residency of microsurgery in the orthopedic hospital, and the residents perform microvascular anastomosis (82% of the flaps) under supervision of more experienced microsurgeons. We observed an increased indication of take-back flap for cases operated by the resident (21 versus 6% when operated by the senior surgeon), but it was not statistically significant, and the presence of complications did not interfere in the success rates of microsurgical flaps. In the literature, some studies[25] [26] [27] observe a higher percentage of complications and increased length of hospitalization when residents perform free flaps. Recalling our residency program, training new surgeons is essential for the future of microsurgery and, in this path, public and university hospitals with high demand for complex orthopedic cases will have resources to perform specialized microsurgical reconstruction when necessary.

Treatment of traumatic limb injuries with microsurgical flaps has higher percentages of total flap loss and complications[28] [29] [30] than flaps for head and neck or breast reconstruction,[15] due to the quality of the recipient vessels and posttraumatic thrombophilia. Our hospital is a referral center for trauma and, commonly, patients with extensive limb injuries requiring microsurgical reconstruction are referred for treatment in our reconstructive microsurgery group after the ideal timing for early reconstruction: < 50% of free flaps are performed within 21 days after the traumatic event, and < 20% within 7 days after the trauma. The complication rates were higher for patients operated > 7 days after the trauma with similar flap survival. Therefore, it is important to emphasize that the presence of a team prepared for microsurgical reconstruction in an orthopedic hospital can reduce postoperative complications, reducing hospital stay and promoting a reduction in costs for public health.

In our study, intraoperative ischemia time > 2 hours was an independent risk factor for free-flap complications. The influence of a longer ischemia time on complications of microsurgical flaps was first demonstrated in breast reconstructions.[15] The longer ischemia time can be associated with several factors, mainly those related to the recipient area and vessels due to the complexity of wounds. This risk factor demonstrates the importance of controlling intraoperative variables, limiting ischemia time, and thus reducing the highest rates of complications in orthopedic reconstructions.

The final success rate of our series of microsurgical reconstruction of limbs resembles studies on microsurgical flaps in published papers, with an overall success rate of 88.3%.

A limitation of the present study is that some technical surgical choices, such as recipient vessels, number of veins, and type of arterial anastomoses, may present bias, since they may be affected by the severity of the wound and by the personal decision of the senior surgeon performing the surgery. The number of cases in the present study is a limitation for the statistical analysis of the influence of individual comorbidities on the incidence of complications. However, the present study is a cross-sectional study with prospective inclusion of all cases of orthoplastic reconstruction of limbs, which allowed drawing some conclusions with an acceptable power analysis.

 

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Conclusion

The independent risk factors for complications of microsurgical flaps for limb reconstruction are obesity and flap ischemia time > 2 hours, and presence of thrombocytosis is a risk factor for partial flap loss. In an orthopedic hospital with reconstructive microsurgery, we recommend being aware of these risk factors to prevent complications.

 

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Conflito de Interesses

Os autores declaram não haver conflito de interesses.

Financial Support

The present study received no financial support from public, commercial, or not-for-profit sources.

Work developed at the Hand Surgery and Reconstructive Microsurgery Group of the Instituto de Ortopedia e Traumatologia do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP, Brazil.

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Publication History

Received: 23 February 2021

Accepted: 18 May 2021

Article published online:
11 March 2022