Surgical Treatment of Haglund’s Deformity: A Systematic Review and Meta-Analysis

Posterosuperior calcaneal prominence, also known as Haglund’s deformity, can often lead to retrocalcaneal bursitis, a significant cause of posterior heel pain. Surgery is indicated for symptomatic patients, after a period of conservative treatment including analgesia, physiotherapy, activity, and shoe wear modification has failed. Surgical options include both open and endoscopic techniques, and typically involve excision of the retrocalcaneal bursa, resection of the calcaneal prominence, and debridement of the diseased Achilles tendon. This article aims to provide an evidence-based literature review for the surgical management of Haglund’s deformity. A comprehensive evidence-based literature review of the PubMed database conducted in July 2021 identified 20 relevant articles assessing the efficacy of surgical modalities for Haglund’s deformity. The 20 studies were assigned to a level of evidence (I-IV). Individual studies were reviewed to provide a grade of recommendation (A-C, I) according to the Wright classification in support of or against the surgical modality. Qualitative and quantitative analysis was performed for the 20 studies. The results show that both open and endoscopic surgical modalities are efficacious in the treatment of Haglund’s deformity, significantly improving functional outcome scores such as American Orthopaedic Foot & Ankle Society (AOFAS) scores and patient satisfaction post-operatively. Endoscopic surgery appears to have the advantage of shorter operative times, lower complication rates, and better cosmesis. More studies are required to further validate and optimize these surgical techniques.


Introduction And Background Introduction
Haglund's deformity is an abnormal bony enlargement at the posterosuperior aspect of the calcaneum, first described by Patrick Haglund in 1927 [1]. Repetitive impingement of the retrocalcaneal bursa between the Achilles tendon and the calcaneal prominence can result in retrocalcaneal bursitis, which is a significant cause of posterior heel pain [2,3]. Patients afflicted with this condition typically describe pain localizing to the retrocalcaneal region [4]. Tenderness can be elicited by palpation laterally and medially to the Achilles tendon at the level of the posterosuperior border of the calcaneum, and with ankle dorsiflexion [2]. Classically, posterosuperior calcaneal prominence associated with retrocalcaneal pain and tenderness is called Haglund's disease.
Lateral X-rays of the ankle can demonstrate posterior calcaneal exostosis, and radiographic measurements such as Fowler's angle and parallel pitch lines are commonly used to determine the degree of prominence [5]. Ultrasound evaluation of the ankle can be used to evaluate retrocalcaneal bursitis and Achilles tendon degeneration and calcifications. Kondreddi et al. showed that patients with degenerative changes in the Achilles tendon had poor subjective outcomes following endoscopic surgery for Haglund's deformity [6].
Surgery level-of-evidence rating ( Table 1) [11]. The studies were reviewed by two orthopedic surgeons and a grade of recommendation (A, B, C, I) was assigned to each intervention based on the classification of Wright ( Table 2) [12]. Selected studies with grades of recommendation A to C were analyzed.

I
Randomized controlled trial with a significant difference or no significant difference but narrow confidence intervals II Prospective cohort study or poor-quality randomized controlled trial (e.g., <80% follow-up) III Case-control study or retrospective cohort study IV Case series V Expert opinion

Statistical Analysis
A total of 14 studies that reported pre-and post-operative American Orthopedic Foot & Ankle Society (AOFAS) scores were included for data synthesis. Among these studies, the surgical effect was evaluated for open and endoscopic surgery groups. The measurement of the surgical effect was the change in the AOFAS score, derived from the difference between pre-and post-operative AOFAS scores reported in the studies. The standard deviation (SD) of the change in AOFAS score was derived according to the Cochrane handbook by using the correlation coefficient (r) formula, in which r = 0.74 was applied in this study [13]. Random effects model with the Restricted Maximum Likelihood (REML) method was used to summarize the overall effect of open and endoscopic surgery on the changes in AOFAS with a 95% confidence interval (CI). Heterogeneity between studies was assessed using Cochrane's Q test and I2 statistics. Sensitivity analysis was performed by including studies with levels of evidence II or III to evaluate the robustness of the result.
Analysis was performed using Stata 16.0 (StataCorp LLC, College Station, TX) and 2-tailed P values <0.05 was considered statistically significant. Qualitative synthesis was also performed to evaluate the surgical interventions reported in the included studies.

Review Results
After a PubMed database search, review of articles, and application of exclusion criteria, 20 final studies were selected for analysis. These studies described their surgical treatments for Haglund's deformity, rehabilitation protocol, and functional outcomes. Table 3 summarizes the general characteristics of selected studies, level of evidence, and grade of recommendation.

Grade of recommendation
The grades of recommendation assigned for each intervention is summarized in Table 5.  They found no significant difference between outcome scores with similar satisfaction rates. They concluded that both techniques provide good clinical outcomes with low rates of complications. The study did not have randomization, and had different post-operative immobilization protocols for the two groups [24].

Studies for Open Surgery
The level of evidence supporting open surgery ranged from level II to level IV. The highest quality study examining the outcome of open surgery was a level II study [4]. Two studies described dorsal closing wedge osteotomy [7,23]. Tourne et al. performed a retrospective cohort study of 40 patients who underwent closing wedge osteotomy over 7 years follow-up (level III) [7]. They found significant improvements in AOFAS scores from 50.5 to 88.9 with 40 excellent, seven good and three fair results. They concluded that closing wedge osteotomy is an efficient and reliable way to change the configuration of the Achilles tendon insertional area and support the efficacy of calcaneoplasty [7]. Ge et al. conducted a retrospective study of 44 patients comparing the outcomes of dorsal closing wedge osteotomy versus posterosuperior prominence resection (level IV). Both groups of patients had significant improvements with AOFAS score improving from 52 to 98 for the dorsal closing wedge osteotomy group and 51 to 93 for the posterosuperior prominence resection group. They found that the dorsal closing wedge osteotomy group had poorer short term outcomes but better functional improvement during long term follow-up [23]. They concluded that open surgical treatment often results in unsatisfied patients, advised caution for recommending treatment and that all possible and prolong conservative treatments should be completed first. The study did not compare pre-operative AOFAS to post-operative scores [14].
Grade of recommendation: Based on the previously mentioned literature, open surgical treatment of Haglund's deformity is assigned a grade B recommendation (fair evidence, level II or III studies with consistent findings).

Studies for Endoscopic Surgery
The level of evidence supporting endoscopic surgery ranged from level II to level IV. The highest quality study examining the outcome of endoscopic surgery was a level II study [6]. Kondreddi et al. conducted a prospective study on a group of patients (25 heels in 23 patients) who underwent endoscopic retrocalcaneal decompression, calcaneal resection, and debridement of unhealthy Achilles tendon over one year follow-up (level II). The patients had significant improvement in preoperative AOFAS from 57.92 to postoperative score of 89.08. They concluded that endoscopic calcaneal resection was highly effective for patients with mild or no degenerative changes in Achilles tendon, had better cosmetic outcomes and fewer complications. Patients with degenerative changes in Achilles tendon had poorer outcomes in terms of subjective satisfaction. Limitations for the study include small sample size and short follow-up [6]. They found all but one patient had improved symptoms, with 15 excellent, four good and one fair result, and no complications. They found that endoscopic surgery has low morbidity, patients have shorter recovery, and patients quickly resume work and sports. The study population was small and did not utilize AOFAS score for comparison [8].
Scholten et al. performed a retrospective study for a group of patients (39 heels in 36 patients) who also underwent endoscopic calcaneoplasty over 4.5 years of follow-up (level IV). Their results showed 24 excellent results, six good results, four fair results, and only two were not improved. They concluded that endoscopic surgery had good results, and had several advantages including low morbidity, excellent scar healing, short recovery time, and quick sports resumption. The study did not utilize the AOFAS score for comparison [2].
Jerosch et al. conducted a retrospective study on a group of 81 patients who underwent endoscopic calcaneoplasty over a period of 35 months follow-up (level IV). Their results showed 41 excellent, 34 good, three fair, and only three poor results. They concluded that endoscopic surgery is effective with a short learning curve, and appeared to less morbidity, less operating time and nearly no complications. The study did not utilize the AOFAS score for comparison [9].
Ortmann and McBryde performed a retrospective study on a group of patients (30 heels in 28 patients) who underwent endoscopic bony and soft tissue decompression of retrocalcaneal space over a period of 35 months follow-up (level IV). Their results showed significant improvement in AOFAS scores from 62 to 97, with 26 excellent, three good, and only one poor result. They concluded that endoscopic surgery has low morbidity, high patient satisfaction, with short return to normal activity. There were limitations of the study including the small cohort and retrospective collection of AOFAS scores for some patients [16].

Discussion
Haglund's deformity remains a significant cause of posterior heel pain. Surgery is indicated after a period of conservative management has failed, with most authors preferring at least six months of conservative treatments. Principles of surgery include excision of inflamed retrocalcaneal bursa, resection of Haglund's deformity, and debridement of unhealthy Achilles tendon [8]. The gold-standard approach to this procedure has not been determined. Endoscopic surgery offers an excellent alternative to open surgery. The use of the arthroscope potentially allows for better visualization [8]. One of the cornerstones for successful surgery is adequate calcaneal resection, which requires good exposure [3]. This potentially requires a larger incision in open surgery which can result in significant wound and soft tissue complications [8]. This may explain some of the differences in complication rates, favoring endoscopic surgery.
Achilles tendon rupture is a potential major complication following surgical treatments. Excessive calcaneal resection and Achilles tendon debridement are risks factors [24]. Based on a biomechanical study by Kolodziej et al., up to 50% of the tendon can be resected from superiorly to inferiorly safely [25]. Ortman and McBryde reported one case of Achilles tendon rupture three weeks following endoscopic calcaneoplasty, which required primary repair [16]. Anderson  He also suggested that longer period of cast immobilization for patients who have also underwent Achilles tendon debridement. However, it is also noted that endoscopic surgery potentially allows better visualization of the calcaneal prominence, and allows more precise local decompression and avoid unnecessary bony over-resection [26].
Operating time and steep learning curve for endoscopic calcaneoplasty have been sources of concern. Jerosch found that after their first 10 cases (mean operating time 46 min), their mean operation time was much reduced to 25 min [9]. Similarly, Leitze found that there was a steep learning curve for the endoscopic procedure, with their first case taking up to two hours which greatly improved to an average of 30 min toward the end of their study [4]. Kaynak found similar experiences in their study, with their operating times improving from 90 min for initial cases to averaging 20-30 min [18]. Pi et al. highlighted the importance of high technical knowledge with good surgical skills and understanding of anatomic relationships for successful endoscopic surgeries [10]. Our study showed that on average, operating time for endoscopic surgery was significantly shorter than open surgery.
Wu et al. suggest further optimization of endoscopic surgery with their three-portal technique. They felt that two portal techniques had difficulty with acquiring convenient manipulation simultaneously with adequate viewing of the calcaneal prominence, and with the limited working space between the two portals place an inherent risk of damage to damaging structures or instruments. They utilize an additional portal, the proximal posterolateral portal mainly as a viewing portal [3].
There are several limitations to our study. There is a significant lack of high-quality evidence, with only two prospective studies. The other studies were level III (five studies) and level IV (13 studies). Majority of the studies were retrospective in nature which are subjected to significant biases. Minor complications may not have been reported which would affect overall complication rates. Due to small number of studies available, results for different approaches (medial, lateral, midline tendon splitting, closing wedge osteotomy) were pooled together for the open surgical group. Similarly, results for different approaches (one to three portals) for endoscopic groups were also pooled together for comparison. It is also important to note there was substantial heterogeneity among the study populations. Our study is also subject to publication bias as they may be other negative studies which are not published.
Our study shows that surgical treatment of Haglund's deformity results in good clinical outcomes. Endoscopic surgery for Haglund's deformity is a safe and efficacious treatment approach with lower complication rates and shorter surgical times. Due to lack of high-quality studies, it only has a grade C recommendation. More high-level evidence research such as randomized controlled trials or prospective studies should be done to further validate and optimize this technique.

Conclusions
Both open and endoscopic surgery for Haglund's deformity has shown to achieve good results, significantly improving functional outcome scores such as AOFAS scores and patient satisfaction post operatively. Endoscopic surgery for Haglund's deformity is non-inferior to open surgery. Potential benefits for endoscopic surgery include better cosmesis, shorter surgical times and lower complication rates. There is a steep learning curve for endoscopic surgery, and requires good surgical skills and understanding of anatomic relationships. More studies are required to further validate and optimize these surgical techniques.

Conflicts of interest:
In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.