We have modified and standardized the technique of minimally invasive operative treatment of intra-articular calcaneal fractures using the 2-point distractor through changes in positioning of the patient, intraoperative radiological viewing, screw placement adjustments, and aftercare. We believe that this technique is advantageous for ORIF in 3 respects. The main advantage of this technique is the reduced rate of wound complications (2.7%) compared to ORIF (16.7%) in our study population. Another important benefit is the possibility of performing the procedure immediately without waiting for the consolidation of the soft tissue. This primarily affects the patient since an immediate operation reduces the pressure on the soft tissue and consequently reduces the level of pain, and it is of socioeconomic interest as the time in the hospital for detumescence is reduced. Last but not least, the overall arthrodesis rate of 4.7% at the Traumacenter Linz is comparable to the literature, although we treat all types of fracture morphologies via minimally invasive means, regardless of the amount of comminution. Arthrodesis is technically easier after minimally invasive procedures.
Many studies have been published concerning the optimal method of treating intra-articular calcaneal fractures. (1–3, 6, 9, 11–15) Most of them lacked a representative number of patients, and therefore, a general consensus is still undetermined. (1, 2, 14)
At the Traumacenter Linz, the demographic analysis revealed relatively young patients (mean 43.3 years) and a male predominance of 3.8:1, which reflects the high socioeconomic influence on this fracture occurrence rate. Causes of injury were high-energy trauma in the majority of patients. Compared to the international literature, falls from heights are the most likely causes of injuries according to Mitchell et al. (16) and Alexandridis et al. (17) Bohl et al. (18) reported a lower incidence of falls, but a higher rate of traffic accidents (49%).
Open reduction and internal fixation (ORIF) has been the preferred therapy for intra-articular fractures. (1, 2) The generally accepted approach for visualization of the fracture site is the extended L-shaped lateral approach, which is considered to be the gold standard. (1) Independent of the approach in ORIF, a consolidation of the soft tissues is recommended. (2, 5, 19) However, it can take 2–4 weeks before the so-called "wrinkle-sign," and decreased swelling occurs. (2, 5) Al-Mudhaffar et al. reported an increased incidence of wound healing problems when the operative procedures were performed within the first week after the injury in an open setting. (19) Rammelt et al. concluded that an operative intervention after 2 weeks also increased the complication rate, which could be explained by increasing fracture consolidation prior to surgery and a resulting need for higher force with reduction. (5) In our described technique, the operation is intended to be performed within the first 3 days after injury. Even with edematous tissue, our method did not lead to an increase in wound healing problems. The earlier the operation was performed, the easier the mobilization of the fragments became.
To overcome problems with wound complications, wound infections, and skin necrosis specifically, many minimally invasive methods to reduce and fix calcaneal fractures have been proposed. (15) At the Traumacenter Linz, this rate was 2.7% using the 2-point distraction method. We believe this is not only a consequence of the operative technique, but also a result of early operative intervention with hematoma evacuation, reduction, and stabilization. This leads to a decrease in the internal pressure.
In a meta-analysis, Fan et al. compared the clinical results after minimally invasive techniques to those after ORIF. Fan et al. reported a lower soft tissue complication rate and reduced duration of the operative procedure. Functional results were almost equivalent for the two groups. (13)
The minimally invasive technique is a standardized procedure at the Traumacenter Linz, and about 86% of all operatively treated fractures have been utilized in the 2-point distractor technique.
Comparisons between the different methods of minimally invasive techniques and ORIF methods are difficult due to a lack of standardized measures, different techniques, and a low number of patients. (12, 15, 20, 21)
Wallin et al. published a systematic review on the clinical results after minimally invasive techniques used to treat calcaneal fractures. The functional results after Sanders type II-IV compared with ORIF were promising, although most of the studies had low evidence levels. Soft tissue complications and duration of the procedure were lower in the minimally invasive group. They did not discuss whether minimally invasive techniques or ORIF led to better anatomic reductions and functional results. (15)
In a randomized, controlled study, Kumar et al. found a lower rate of wound healing problems and better functional outcomes in the minimally invasive group, compared with those after ORIF. The better functional outcomes were explained by a lower wound complication rate and a better anatomical reconstruction. (22) In terms of anatomic reconstruction, ORIF is still considered the gold standard for intra-articular fractures. (1, 2, 9, 13)
In 2007, Schepers et al. presented their results on minimally invasive methods with a follow-up of 3 years. Functional results after minimally invasive techniques were lower compared to those reported after ORIF. The infection and wound complication rates were similar to those of ORIF. Subtalar joint motion could be restored to nearly 70% compared to the uninjured side. The secondary arthrodesis rate was higher than in Buckley’s study from 2002. (23, 24)
It seems that the most crucial factor for gaining a satisfactory result, according to Veltman, is the absence of complications. (1) Also, other authors concluded that patients show the best results when the operative procedure and aftercare were complication-free. (2, 3) Patients with comorbidities such as vascular diseases, diabetes, and nicotine abuse are more prone to these perioperative complications. (2) Also, patients over 60 years old are more likely to be affected by postoperative complications and subtalar arthritis, although this may be linked to the higher rate of comorbidities. (2)
The published rate of arthrodesis is between 0 and 15% after minimally invasive surgery: 0–12% after ORIF, and 3.8–17% after conservative means. (23–32) The subtalar arthrodesis rate of 0% described by Park et al. was based on a relatively low number of patients and only one year follow-up. (29) In extremely complex intra-articular fractures, a primary subtalar arthrodesis is postulated to achieve satisfactory results. (2)
The secondary subtalar osteoarthritis rate requiring arthrodesis after minimally invasive techniques was 4.7%. Between 2007 and 2015, this arthrodesis rate was almost constant. A primary subtalar arthrodesis was not performed in our group of patients. The secondary arthrodesis rate of 4.7% after operative intervention in our study is comparable to that of the current literature. In a study published by Buckley et al., 37 of 218 (16.9%) patients required an arthrodesis, whereas 7 of 206 operatively-treated patients (3.4%) required a secondary operative intervention. (33) More prospective randomized studies with longer follow-up periods are required to compare the results of minimally invasive techniques with ORIF and conservative treatment.
After conservatively treated calcaneal fractures, a 6-fold higher likelihood of arthrodesis has been published compared to primarily operated patients. Furthermore, patients with Sanders Type IV and patients with a Boehler angle of 0 degrees had a notably increased risk of secondary subtalar arthrodesis. (34) Operative reconstruction after calcaneal fractures does provide a better basis for a secondary subtalar arthrodesis and does lead to better long-term results. (9)
Functional results after minimally invasive treatment are equivalent to those of ORIF. (35, 36) Based on these functional results with lower complication rates, two recent sets of authors have argued that minimally invasive techniques are a better option for the treatment of intra-articular fractures. (13, 15)
This study has certain limitations and weaknesses that must be considered.
First and foremost, we have no clinical evaluations with comparative scores for our patients. This study was entirely focused on the rate of wound complications, the need for secondary arthrodesis, and relevant characteristics such as demographic data and socioeconomic data.
Future comparative studies are needed to verify the safety of operative procedures for calcaneus fractures. Whether this new technique will result in satisfactory long-term outcomes or can prevent post-traumatic osteoarthritis was not fully determined.