Incidence of Wounds Associated with Posterior Midline Incision for Achilles Tendon Pathology in a Large Cohort at a Tertiary Care Center

Abstract

Background: We sought to determine the wound complications associated with a straight midline incision overlying the Achilles tendon. Data on sex, age, body mass index (BMI), surgery performed, date of surgery, and wound development were collected. Methods: We retrospectively collected data on 217 patients with a mean ± SD age of 46.16 ± 13.72 years and follow-up of 9.1 ± 12.42 months. The specific procedures performed with this incision included repair of ruptured Achilles tendon (n = 89), Haglund deformity correction (n = 75), and flexor hallucis longus tendon transfer (n = 63). Wound complication was defined as a delay in wound healing with necrosis of the incisional margins resulting in exposure of superficial or deep layers. Deep infection was defined as the need for intravenous antibiotics. Results: We reported 15 wound complications (6.91%): ten (4.6%) were superficial and five (2.3%) were deep. All five patients with deep wound complications required operative debridement, and four patients required intravenous antibiotics. The infection rate of the midline incisional approach was 1.83%. Superficial wound complications were treated with local care and oral antibiotics, as necessary. There were no significant differences between age (P = .5986; P < .05), BMI (P = .7968; P < .05), smoking history (P = .6356; P < .05), or length of follow-up (P = .8338; P < .05). The overall wound rate of 6.91% is comparable with other literature with larger cohorts. Conclusions: These results will help us better educate surgeons about the risk of wound development with the posterior midline Achilles tendon incision.

Achilles tendon pathology is a common problem that affects both competitive athletes and laypeople. Injuries, including acute Achilles tendon rupture and chronic Achilles tendinopathy, can lead to debilitating pain and a reduction in activity. Once conservative options have been exhausted for the pathology, aside from acute rupture, surgical intervention is commonly used to provide relief.

Surgical intervention often consists of a posterior incision, either straight versus serpentine or midline versus medial, which allows appropriate visualization of the tendon. With an overall complication rate of 7% to 30%, there is debate in the literature as to which surgical approach for Achilles tendon pathology is superior [1,5,6]. Historically, the complication rate for a midline Achilles incision has been documented to be 14% [2]. Attinger et al [3] describe the vascular supply to the posterior heel from the peroneal and posterior tibial arteries via one to three transverse communicating vessels. They continue to explain that a posterior midline incision is recommended because the approach safely divides the peroneal and posterior tibial angiosomes [3]. Therefore, we believe that a posterior midline incision is the safest option for repairing all Achilles tendon pathologies.

Most studies on the incisional approach focus on other complications, such as neuritis, irritation, and continued pain, or simply one facet of Achilles tendon pathology, ie, Achilles tendinopathy [1]. The aim of the present study was to look at the incidence of wounds associated with the posterior midline incision in a large cohort with acute and chronic Achilles tendon pathology.

Methods

After receiving formal institutional review board approval from the University of Pittsburgh Human Research Protection Office, we obtained the electronic medical records of the senior authors (P.R.B., J.M.). Between 2006 and 2018, a retrospective medical record review was performed of all of the surgeries performed by the two primary surgeons (P.R.B., J.M.), and patients who underwent surgery for Achilles tendon pathology were isolated. A spreadsheet was maintained by the senior authors for these patients, which included sex, age, body mass index (BMI; calculated as the weight in kilograms divided by the square of the height in meters), previous surgeries performed, smoking history, diabetes status, date surgery performed, wound complications (defined later herein), symptomatic scarring, and the need for repeated operating room (OR) trips. Patients who had previously undergone Achilles tendon surgery, had a septic joint requiring a posterior incision, or had previous ulceration in the area were excluded.

Patients were considered for this study if they underwent surgery with one of the two primary surgeons using a posterior midline incision over the Achilles tendon. Both surgeons had similar training, resulting in comparable operative technique, closure, and postoperative protocol. All of the Achilles tendon pathology surgeries were included. All of the surgeries were performed with a posterior midline incision overlying the central aspect of the Achilles tendon. All of the incisions were closed primarily using a standard layer closure consisting of reapproximating the paratenon and subcutaneous layer with absorbable sutures (poliglecaprone 25 [Monocryl; Ethicon Inc, Raritan, New Jersey]) and skin closure with nonabsorbable sutures (nylon versus polypropylene [Prolene; Ethicon Inc]). The surgeries that were included in this study were Haglund resection, acute Achilles tendon repair, and flexor hallucis longus (FHL) tendon transfer. A surgical incision wound was defined as a delay in wound healing with necrosis of the incisional margins resulting in exposure of superficial or deep layers [4]. When the wound edges begin to separate but the overlying fascia remains intact, this was considered a superficial wound. A deep wound was defined as one that exposed the Achilles tendon, and infection may be present. An infection was defined as having erythema and warmth and was treated with intravenous or oral antibiotics. All of the patients received a well-padded posterior splint in the OR, followed by a 7- to 10-day follow-up and placement into an Achilles wedge controlled ankle motion (CAM) boot, with subsequent follow-up visits at 3 and 6 weeks.

Surgical Technique

During the procedure, care was taken to ensure proper identification of layers, most importantly the paratenon. The incision was extended if the primary surgeons determined that tension was present along the incision line. Care was taken while retracting to reduce excessive stress to soft tissue. The primary surgeons ensured that only blunt retraction was used and that the retraction was relaxed when the surgical field did not need to be exposed, ie, when gathering materials, flushing, or using fluoroscopy.

Before closure, the tourniquet was deflated to allow for hemostasis of bleeding vessels. Of note, for both primary surgeons, before fixation of the FHL into the calcaneus, the tourniquet was deflated. The surgeons believe that this allows for hemostasis of all bleeding vessels and ensures that appropriate closure over the FHL tendon can be performed, decreasing the risk of hematoma. The surgeons also found that this helped with postoperative swelling and tension on the soft tissue. Primary closure of the paratenon was performed with 4-0 Monocryl sutures, using a locked running stitch. The skin edges were then approximated with 4-0 Monocryl sutures, and soft-tissue closure was performed in an interrupted horizontal fashion with 3-0 nylon or 3-0 Prolene sutures, depending on the surgeon.

Results

There were 217 patients who underwent Achilles tendon surgery with the two primary surgeons (P.R.B., J.M.). The mean ± SD age of the patients was 46.16 ± 13.72 years. All of the patients received the same incision regardless of procedure, as well as the same closure and postoperative protocol. All of the incisions were performed through a posterior central, or midline, approach, overlying the Achilles tendon. All of the incisions were closed with absorbable and nonabsorbable sutures in a layering fashion. The types of procedures included repair of Achilles tendon rupture (n = 89), Haglund deformity correction (n = 75), and FHL tendon transfer (n = 63). The present data show that ten of the 217 patients had multiple procedures performed concurrently; for example, a patient may have had a Haglund resection followed by an FHL tendon transfer. Mean ± SD follow-up was 9.1 ± 12.42 months. There were 51 patients (23.5%) who identified as smokers, with a total pack-year mean ± SD of 19.07 ± 12.76 years. The mean ± SD BMI was 32.09 ± 7.14 (Table 1).

Table 1. Demographic Characteristics of the 217 Study Patients

Table 1. Demographic Characteristics of the 217 Study Patients

Of the 217 patients, 15 (6.91%) presented with a wound complication during follow-up. All of the wound complications occurred within the confines of the posterior midline incision; however, most (ten of 15) of those wound complications were superficial (66.67%). Five patients presented with a deep wound complication, which was 2.3% of the 217 patients. There were no significant differences in age (P = .5986; P < .05), BMI (P = .7968; P < .05), or length of follow-up (P = .8338; P < .05) between patients who developed a wound and those who did not (Table 2).

Table 2. Results

Table 2. Results

Four patients with a smoking history presented postoperatively with a wound; however, there was no noted significance comparing smoking and wound development (P = .6356; P < .05). Of the 15 wound complications, seven were documented as superficial and resolved with local care only. No oral antibiotics were prescribed. However, eight (three superficial wounds and five deep wounds) of the 15 patients required a return to the OR. This was 3.68% of the 217 patients in the cohort. All five of the patients with a deep wound complication required a trip to the OR for debridement. Four patients, or 1.84% of the total cohort, received intravenous antibiotics secondary to their wound because they presented with erythema surrounding the incision site.

Of the patients who required OR debridement, one had documented noncompliance and a medical history of peripheral neuropathy (FHL tendon transfer). This patient required the most extensive debridement, along with consultation with plastic surgery for assistance with wound coverage. One patient developed a hematoma, which required decompression in the OR (FHL tendon transfer), and another had a reaction to the deep suture material, which required removal in the OR (Haglund resection). Another patient who required OR debridement had a medical history of diabetes, with a hemoglobin A_1c level of 11.7 and peripheral neuropathy (FHL tendon transfer). One patient who required operative debridement admitted to early weightbearing in their postoperative period (FHL tendon transfer). The other three patients who returned to the OR required surgical debridement and reapproximation. A return to the OR included extensive wound excision, irrigation and debridement, and an attempt at repeated closure.

Two patients (13.33%) noted irritation from their CAM walker, which resulted in superficial wound development, but both wounds resolved uneventfully (Haglund resection, FHL tendon transfer). A suture abscess caused a superficial wound complication in three patients (20%) (FHL tendon transfer, Achilles tendon repair, and Haglund resection). However, none of these patients required a trip to the OR or treatment with antibiotics, and all of them healed uneventfully.

The types of procedures were also recorded for individuals who experienced a complication. Eight patients underwent FHL tendon transfer, eight patients underwent Haglund resection, and four patients underwent acute Achilles tendon repair. There was no significant relationship between the patient's surgery and wound development (P = .0787; P < .05).

All of the patients, regardless of whether they had a superficial or a deep wound complication, healed after appropriate management. Even when other services, such as plastic surgery, were involved, all of the wounds healed in the same amount of postoperative time, and there was no noted increase in follow-up.

Discussion

The purpose of this study was to look at the incidence of wounds with a posterior midline incision for Achilles tendon pathology in a large cohort of patients treated by the two primary surgeons (P.R.B., J.M.). This incision is advantageous because it lies between two angiosomes [3]. The posterior midline incision lies centrally between the peroneal and posterior tibial angiosomes yet remains medial to the sural nerve [3,5]. We believe that this approach is safe, with an unestablished wound incidence in a large cohort. The wound rate for Achilles tendon surgery has ranged from 10.0% [6] to 31% [8]. Hörterer et al [2] conducted one of the largest studies, to our knowledge, to document complications associated with posterior midline Achilles tendon incisions for Achilles tendinopathy. In their study, 118 patients were operated on by one surgeon, with a total minor complication rate of 14%. The studies differ in that their complication rate is not solely focused on the incidence of wounds. Hörterer et al [2] focused on other complications, such as neuritis, scar formation, and limitations in shoes. The present study is in line with Hörterer et al in that both studies looked at similar complications of the posterior midline incision. The study by Hörterer et al looked only at the posterior midline incision for Achilles tendinopathy, whereas the present study demonstrates the wound rate for most Achilles tendon surgeries.

Hunt et al [8] evaluated 39 patients who underwent surgical treatment of Achilles tendinopathy with or without FHL tendon transfer. However, their incision approach was variable depending on the primary surgeon who was performing the procedure and included posterolateral, central, and posteromedial [8], which differs from the present study. All of their complications were found to be minor, and all involved surgical wound complications. They stated that all of the wounds healed without surgical intervention.

Saxena et al [7] evaluated 219 surgical cases pertaining to Achilles tendon pathology. They noted that all of their Achilles tendon surgeries had a 10.0% complication rate; however, the length of the Achilles tendon incision varied depending on the type of surgery performed. For certain pathologies, they would use a serpentine type of incision, and for ruptures and debridement, they used an incision medial to the Achilles tendon [7]. Never in the study was a posterior midline incision used; however, this study does present a similar cohort and multiple surgeries involving the Achilles tendon.

McAlister et al [9], in their 2015 study on the posterior midline approach for detachment and reattachment of the Achilles tendon, found a higher incisional wound complication rate of 9.0% (nine of 100), with seven of the nine patients (77.8%) requiring a trip to the OR for irrigation and debridement. This compares with the present study, which had a larger patient population (N = 217), a wound complication rate of only 6.91% (15 of 217), and a lower rate of operative debridement of 53.3% (8 of 15). Paavola et al [10] analyzed 432 patients treated surgically for chronic Achilles overuse pathology and reported their complications. Their study showed 14 skin edge necroses, 11 superficial wound infections, five seromas, and five hematomas, with nine of these patients requiring repeated operation. This creates a complication rate (excluding their scar formations, sural nerve irritation, and partial ruptures) of 8.1% (35 of 432) and a repeated operation rate of 25.7% (nine of 35). In 14 of their patients with skin edge necroses, four required repeated operation, and in addition, three required resuturing of the wound; the other seven patients were treated with local care and intravenous antibiotics. Wagner et al [11], in their 2006 study discussing the results of Achilles tendon detachment and reconstruction for insertional Achilles tendinosis, demonstrated 12% wound complications, including wound development and wound infection, in 75 patients. Comparing these with the present study, we demonstrated a lower incisional complication rate and a lower repeated operation rate for those complications.

In a smaller study published in Foot and Ankle International, Johnson et al [12] performed a central tendon splitting technique for their insertional calcific Achilles tendinosis pathology. Their study included 22 patients, with mean follow-up of 34 months. They demonstrated improvements in American Orthopaedic Foot and Ankle Society scores and pain and had only two superficial wound complications that did not require another operation. This is a wound complication rate of 9.1% (2 of 22). This is most likely due to differences in the postoperative protocol; the present patients were routinely placed in well-padded splints, whereas these researchers immediately placed their patients in a CAM boot. Another smaller study by Nunley et al [13] demonstrated a more comparable wound complication rate, as they documented only one superficial wound complication in their series of 27 patients. They noted that this patient did not require additional surgical operations.

McGarvey et al [14] published a series of 22 operations for insertional Achilles tendinosis using a central tendon–splitting technique. Their study stated that only 13 of 22 patients healed the incision and returned to work without pain. They noted that two patients had delayed healing, one had superficial infection treated with oral antibiotics, two had scar-related sensitivity, and four had numbness. Calder and Saxby [15] evaluated a midline splitting incision for a calcific Achilles tendon and noted that there were three superficial wound infections in 49 patients, which gives a rate similar to ours, although they do not mention or reference wound development in this study. Maffulli et al [16] also published a study looking at midline incisions for calcific insertional Achilles tendinopathy in 21 patients. They stated that two patients experienced a superficial incisional infection but did not list any wound development. These studies, although quite smaller than the present series, discussed comparable infection and wound complication rates, yet the present study differs in that we included multiple Achilles tendon pathologies with a larger cohort.

The present study, compared with those previously mentioned, used two surgeons who performed the same posterior central incision for all Achilles tendon pathologies, regardless of acute or chronic nature. Similar to Saxena et al [7], the present study comprised 217 individuals with a variety of Achilles tendon procedures performed. This study differs from that by Saxena et al in that they did not use a posterior midline incision for any pathology. In their study, a posterior medial incision or a serpentine-type incision was used, depending on the pathology they were treating. We have a favorable wound rate of 6.91% compared with Saxena et al. Also, deep wound development was only 2.3%. Another positive finding compared with this study was the postoperative infection rate for the posterior midline incision, which was 1.83% in the present study. However, all of those who presented with a postoperative infection of their incision also presented with a wound. The present infection rate may differ from previously reported rates because we accounted for only postoperative infections as requiring intravenous antibiotics.

This study, to our knowledge, is one of the largest in evaluating wound complications associated with the posterior midline incision for all Achilles tendon pathology. The rate of incisional wounds, 6.91%, is similar to that of the studies with larger groups that have already been mentioned. Regarding the 15 complications, 47% of patients who presented with a wound did not require any treatment other than local care. We found that 13.33% of patients who presented with a wound had secondary CAM boot irritation. This complication was mitigated with proper padding and off-loading of the incision and better patient education on the air bladder systems in these devices.

The present study showed that 20% of the wound complications were secondary to suture irritation or suture abscesses. A suture abscess was found in two patients who underwent a Haglund resection and in one patient who underwent an FHL tendon transfer. All of the suture materials may lead to an immunologic or inflammatory reaction. It is known that absorbable sutures generate more reactions than nonabsorbable ones, and multifilamentous sutures may lead to issues as well. Further studies should be conducted to determine whether absorbable sutures play a role in this complication given the lack of fat in the Achilles region to help hydrolyze absorbable sutures.

One encouraging finding from this study is that there was no statistically significant difference between length of follow-up and whether the patient developed a wound. Even when one of the patients required an intervention with a plastic surgeon, the patient's overall follow-up remained consistent with the rest of the cohort. In turn, all of the patients, regardless of wound, were healed at their final follow-up.

There are several limitations to this study. First and foremost, all of the patients in this study received 1 week of prophylactic oral antibiotics in an outpatient setting. There is limited literature regarding prophylactic antibiotics for foot and ankle surgery. Dayton et al [17] looked at research from six studies with several panel members and found that more high-level evidence is needed regarding antibiotic drug use. They believe that prophylaxis at most institutions will continue due to the few complications associated with the practice.

One limitation is the retrospective nature of the study; however, most of the large-scale Achilles tendon literature is retrospective as well. Another limitation is the length of follow-up as it documented that granulomas do appear later in the postoperative period, which could lead to potential wound complications. A limitation of the study is that it evaluated solely the complications associated with wounds to the posterior midline incision. We did not go into depth about other complications, such as adhesions or neuritis, because the purpose of this study was to report on wound development with the posterior midline incision in a large cohort, and we felt that this information was superfluous.

Another limiting factor of this study is involvement of the FHL tendon transfer. Although we did not note a statistically significant difference from the FHL tendon transfer procedure, this procedure does require more dissection comparatively and, thus, would benefit from further studies compared with this approach. Last, further studies would benefit from going into depth about whether adhesions could play a role in wounds associated with the posterior midline incision.

A final note is that all of the studies included in the discussion were based on studies performed by one surgeon, aside from that by Hunt et al [8]. This could be seen as a strength, but it is important to note that the present study had two main surgeons performing the posterior midline incision.

Conclusions

The posterior midline incision for Achilles tendon pathology has the same risks as other incision locations. We found a 6.91% risk of wound development for the posterior midline incision for all Achilles tendon pathologies, with an infection rate of 1.83%. More than 47% of these complications healed uneventfully without the need for OR debridement. All of the patients, regardless of whether they experienced wounds, ended up healing with appropriate treatment. Some complications may be avoided, such as CAM boot irritation. However, some wounds may be unavoidable when addressing Achilles tendon pathology with use of the posterior midline incision. The results of this study will help us better educate surgeons on the risk of wound development with the posterior midline Achilles tendon incision.