Introduction

Elbow stiffness usually occurs after elbow trauma. Depending on the patient’s requirements, even a small loss of motion can lead to severe functional limitations of the elbow joint. These limitations may substantially reduce the patient’s quality of life. If conservative treatment does not provide a satisfying result, arthrolysis of the stiff elbow can be performed either arthroscopically or by an open approach aiming to relieve pain relating to mechanical symptoms and impingement and to recover a functional range of motion (ROM) [3, 8]. Although satisfactory outcomes are reported in retrospective comparative studies and case series for both procedures, there is a paucity of direct prospective comparisons of the two techniques [3, 9].

Hence, the aim of the study was to analyze the clinical short-term results of arthroscopic and open elbow arthrolysis in postoperative and posttraumatic stiff elbows.

Methods

A total of 126 patients treated with elbow arthrolysis were enrolled in this prospective study. The indication for surgery was elbow stiffness resistant to conservative medical treatment over a minimum of 3 months. Patients that received additional hardware removal during surgery or other additional surgical procedures (for example, ligament reconstruction due to inherent instability), as well as patients with incomplete postoperative evaluation forms during the defined follow-up times, were excluded. After application of these criteria, 44 patients could be included in the study population.

Group 1 included patients receiving arthroscopic arthrolysis. It consisted of 18 (54.4%) women and 15 (27.6%) men, with an average age of 45.5 years (range, 19 –72 years).

Group 2 included patients after open arthrolysis and consisted of four (36.4%) women and seven (64.4%) men, with an average age of 38.6 years (range, 19 –67 years). Previous surgery was performed in 13 patients (43.3%) in the arthroscopic group (four arthroscopic procedures, nine open procedures) and seven patients (63.4%) in the open group (six open procedures, one arthroscopic procedure).

Demographic characteristics are presented in Table 1. Patients were evaluated preoperatively for age, sex, dominant limb, pain score (numerical rating scale; NRS), ROM in extension and flexion, as well as disabilities of the arm, shoulder, and hand (DASH) score.

Table 1 Demographic characteristics of the two groups
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The operative techniques for open and arthroscopic procedures have previously been described in detail [5, 8]. In addition to the standard arthroscopic procedure, seven patients in this group underwent ulnar nerve decompression.

After surgery, the patients were clinically examined in a standardized fashion including the clinical outcomes by using DASH score, NRS, and ROM (extension/flexion) 6 weeks, 3 months, and 6 months after surgery. Furthermore, the question of whether patients would opt for this surgery again was reviewed.

Postoperative management

Postoperative management was identical for both cohorts. In particular, postoperative progressive active motion was allowed after day 1, which was encouraged under the instruction of a clinical physician. An additional temporary splinting (Mayo orthosis, DJO Global, Vista, CA, USA) was applied for the first 2–4 weeks to increase and maintain ROM in extension and flexion.

Statistical analysis

The empirical distribution of the parameters defining clinical outcome in this study was described by tabulation of the mean, standard deviation, minimum, and maximum. The Mann-Whitney U test was performed to analyze the variables in the two groups. A two-tailed p value of <0.05 was considered significant. All analyses were performed in SPSS 23 (IBM Inc., Armonk, NY).

Approval was obtained from our institutional review board.

Results

In the arthroscopic group, the preoperative ROM arc improved significantly from 103.3° (±23.4) to 116.3° (±15.5°; p = 0.01) after 6 weeks and increased to 120.9° (±15.1°; p = 0.001) after 3 months and 123.5° (±12.5°; p = 0.001) after 6 months. In the group receiving open arthrolysis, the mean ROM arc also increased significantly from 64.5° (±31.1°) to 93.2° (±21.7; p = 0.028) after 6 weeks, 98.2° (±21.6°, p = 0.015) after 3 months and 100.9° (±25.6°, p = 0.007) after 6 months (Fig. 1). The gain in elbow motion between the two groups showed no significant differences compared to preoperative values (p > 0.05; Table 2).

Fig. 1
figure 1

Preoperative and postoperative range of motion (extension/flexion). Significant differences compared to the preoperative values are marked by black asterisks

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Table 2 Delta values compared to preoperative status. Comparison of both groups
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In the arthroscopic group, the mean DASH score was 37.3 points (±23.4 points) preoperatively, improving to 29.7 points (±23.3 points, p = 0.16) after 6 weeks, 21.1 points (±20.9 points; p = 0.005) after 3 months, and 16.1 points (±16.5 points, p = 0.001) after 6 months. In the open arthrolysis group, the DASH score improved postoperatively compared to its preoperative value by 38.2 points (±24.1 points). A score of 35.4 points (±16.2 points, p = 0.76) was recorded after 6 weeks, 28.9 points (±24.3 points, p = 0.52) after 3 months, and 19.45 points (±17.5 points, p = 0.02) after 6 months (Fig. 2).

Fig. 2
figure 2

Preoperative and postoperative evaluations of the disabilities of the arm, shoulder, and hand score. Significant differences compared to the preoperative values are marked by black asterisks

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Similarly, the NRS decreased after surgery in both groups. However, only in the arthroscopic group did the reduction of pain showed statistical significance. In the arthroscopic group, the NRS decreased from 5.5 points (±2.5 points) preoperatively to 3.1 points (±2.7, p = 0.002) after 6 weeks, and from 2.9 points (±2.6 points, p = 0.001) after 3 months to 2.3 points (±2.3 points, p =0.001) after 6 months. Comparably, the NRS dropped in the open group from 4.6 points (±2.8 points) to 3.7 points (±1.9 points; p = 0.34) 6 weeks postoperatively, 3.0 points (±2.4 points, p = 0.30) after 3 months, and 2.6 points (±2.4 points; p = 0.15) after 6 months (Fig. 3).

Fig. 3
figure 3

Preoperative and postoperative evaluations of pain (numerical rating scale). Significant differences compared to the preoperative values are marked by black asterisks

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When comparing the delta values of the groups between the preoperative ROM, DASH score, and NRS, no significant changes could be seen (p > 0.05; Table 2).

After 6 months, 32 patients (96%) in the arthroscopic group and all patients in the open group stated that they would opt for the respective surgery again. Neurovascular complications and infections did not occur in either group.

Discussion

The present prospective study analyzed the clinical short-term results of arthroscopic and open elbow arthrolysis. The outcome was evaluated using the range of elbow motion, pain on an NRS, and the DASH score. Both techniques resulted in satisfactory to excellent functional recovery in the cohorts presented here. This is supported by the finding after 6 months that 32 patients (96%) in the arthroscopic group and all 11 patients in the open group indicated that they would opt for the respective surgery again. Significant improvements in elbow motion were found in both cohorts compared to preoperative values. After 6 months, the mean increase in ROM in the open group reached 36°, whereas the arthroscopic group recorded an increase of 21°. The improvement in elbow motion between the two groups showed no significant differences. However, a tendency towards a higher improvement in elbow motion in the open group is in line with a previous systematic review that reported a higher increase in ROM in studies evaluating the outcomes after open procedures (mean ROM 52°) compared to the arthroscopic series (mean ROM 40°) [6]. This might be due to the fact that, in the authors’ department, open arthrolysis is predominantly performed in elbows with a larger restriction of motion (open group mean ROM 64.5° vs. arthroscopic group mean ROM 103.3°). Large intrinsic components are managed by a more aggressive approach, which allows for releasing the posterior band of the medial collateral ligament (MCL) in order to achieve higher degrees of motion, especially in flexion. Furthermore, these results are supported by a recent retrospective study that reported better outcomes regarding flexion limitation after an open procedure in osteocapsular arthroplasty for primary osteoarthritis compared to an arthroscopic group after a mean follow-up time of 36.6 months [7]. As discussed in recent literature, additional mini-open ulnar nerve decompression and posterior MCL bundle release could be a promising additional procedure to the arthroscopic approach to increase elbow flexion in cases of severe stiff elbow [7].

Nevertheless, the excellent arc of elbow motion of 123.5° in the arthroscopic group after a follow-up period of 6 months leads to the conclusion that, in most elbows, arthroscopic osteocapsular release enables fully acceptable exposure for the removal of osseous components, such as ectopic bone and osteophytes, and capsular release. These conclusions are supported by the satisfactory results of the outcome variables of the DASH score and the decrease in pain levels. In the arthroscopic group, the mean DASH score of 37.3 points improved significantly to 16.1 points after 6 months, while the NRS decreased from 5.5 points to 2.3. These results are supported by several studies reporting the arthroscopic procedure to be effective in patients with posttraumatic elbow contracture [2, 9,10,11,12,13]. However, due to the proximity of neurovascular structures, arthroscopic arthrolysis is a challenging procedure of high technical complexity [4, 8]. Therefore, the open procedure is considered by several authors to be the standard treatment for managing contracted elbows, especially in elbows with large intrinsic and extrinsic components [3, 6].

Although no complications were observed in either cohort reported here, the literature discusses the volume of complications as rising with the extent of the surgical procedure, which in turn suggests that less invasive procedures are favorable [6]. Therefore, the results presented here strongly support an arthroscopic approach in contracted elbows [1, 6]. The transition to an arthroscopic approach is, in the authors’ view, preferable if the surgeon has the necessary experience and skills in the field of arthroscopy, especially in the case of difficult and challenging posttraumatic elbow stiffness.

Several limitations apply to this study. The first limitation of the study was the comparably small size and unbalanced sampling of cohorts, which enhances the risk of a type 2 error. Moreover, since the arthroscopic approach is performed predominantly in stiff elbows in the authors’ clinic, it is difficult to directly compare the procedures with different groups due to the risk of a patient selection bias and confounding factors. However, since additional confounding surgical factors, like hardware removal or ligament reconstruction, were excluded, the authors are confident that they achieved homogeneous patient cohorts.

Conclusions

It was possible to compare the clinical short-term results of arthroscopic and open elbow arthrolysis in a prospective study. Good to excellent functional recovery was observed in both cohorts when evaluating improvements in the DASH score, the gain in elbow motion, and the decrease in pain. When comparing the delta values of the groups between the preoperative status and postoperative follow-up, no significant changes were found. This might be due to the comparably small size and unbalanced sampling of the cohorts. Nevertheless, certain tendencies were observed. While the mean gain in elbow motion in the open group reached 36° after 6 months, the arthroscopic group achieved an increase of 21°. Meanwhile, the decrease in the DASH score and pain was higher in the arthroscopic group. As no neurovascular complications and infections occurred in either group, both procedures must be considered as valid options to treat posttraumatic elbow stiffness. In light of these considerations and the advances in minimally invasive surgical techniques, the arthroscopic approach has evolved to become an essential option and alternative to treat posttraumatic elbow stiffness.