The Impact of Lateral Decubitus vs. Beach Chair Positioning on the Clinical Outcome of the Patients with Isolated SLAP Type II Repair: A Systematic Review and Meta-analysis

Abstract

Background:

A superior labrum from anterior to posterior (SLAP) repairs can be performed in either beach chair (BC) or lateral decubitus (LD). The purpose of this study was to perform a systematic review and meta-analysis to compare the outcomes of surgical repair of type II SLAP injuries between the BC vs. LD positions. We hypothesized no statistically significant differences in the functional, pain, and motion outcomes between the BC vs. LD positions after type II SLAP repair.

Methods:

A comprehensive literature search was performed using MEDLINE, Scopus, Web of Science, Embase, and Cochrane to identify studies reporting outcomes after type II SLAP repair. Outcome measures consisted of pain using the visual analog score (VAS), range of motion (ROM), and functional scores, including the University of California at Los Angeles Shoulder (UCLA) score, American Shoulder and Elbow Surgeons (ASES), and Constant score. The outcomes were pooled and analyzed for eligibility and stratified into two subgroups for a random-effects model meta-analysis.

Results:

Of the 8,016 identified studies through a database search, 13 papers (378 patients) were eligible for statistical analysis in the BC and 10 articles (473 patients) were included in the LD group. The mean follow-up for BC and LD was 35 and 44 months, respectively. The SLAP repair in both positions demonstrated improvements in postoperative clinical outcomes and ROM. Comparing the two positions, the LD group demonstrated significantly greater improvements in VAS which contributed to better functional outcomes, while the BC group showed a significantly greater improvement in abduction. No other differences were identified including ASES, UCLA, and Constant score as well as remaining ROM.

Conclusion:

Based on the findings of this systematic review and meta-analysis, both the BC and LD positions provide patients better outcomes following operative repair of type II SLAPs. While LD represented a better improvement in functional outcome measures, the BC position demonstrated better abduction with no other significant differences between both positions. An individualized approach to position selection concerning the patient’s complaint (pain vs. motion) as well as the surgeon’s discretion is recommended.

Introduction

Injury to the superior labrum was first described in 1985 and defined as a superior labrum from anterior to posterior (SLAP) lesion.¹ Reported etiologies include hyperextension, falling on an outstretched arm, heavy lifting, throwing, and overhead activities, as they create traction on the long head of the biceps brachii and its labral attachment.^2,3 These injuries may be isolated or be accompanied by other soft tissue and bony lesions, including Bankart and rotator cuff injuries.⁴ Originally, SLAP injuries were classified into four types by Snyder et al.,³ which was further expanded to seven types by Maffet et al.⁵ with type II injuries being the most common in which both the superior labrum and biceps tendon detached together from the superior glenoid rim.² Surgical repair of the isolated, symptomatic type II SLAP lesions is often performed in younger athletes. An operative SLAP repair can be performed in one of two different positions, including beach chair (BC) and lateral decubitus (LD), depending on the surgeon’s preference, comfort, and training.

Both BC and LD have been shown to result in satisfactory outcomes when addressing different shoulder pathologies.⁶ A systematic review comparing both positions for arthroscopic capsular release showed no significant difference in recurrence rate, patient-reported outcome scores, and range of motion.⁷ Moreover, a systematic review on posterior shoulder stabilization showed no significant difference between the two positions in terms of recurrent instability and return to the sports.⁸ However, comparing the number and position of suture anchors during arthroscopic anterior shoulder stabilization LD position was associated with the utilization of more anchors that are more frequently placed in the 6 -o’clock position compared to the BC position.⁹ This data suggests that while the two positions are technically different, the outcomes are expected to be comparable. There is no similar data comparing the two positions during type II SLAP repair.

A review of current literature reveals that there is no dominant choice based on objective data, and we speculate that position selection is based almost solely on surgeon preference.¹⁰ The purpose of this study was to perform a systematic review and meta-analysis to compare the outcomes of surgical repair of type II SLAP injuries between the BC and LD positions. We hypothesized no statistically significant differences in the functional, pain, and motion outcomes between the BC and LD positions after type II SLAP repair.

Materials and Methods

Search Strategy

Five different databases (MEDLINE, Cochrane, Web of Science, Embase, and Scopus) with the following keywords: “SLAP” OR “Superior labrum anterior to posterior” OR “Superior labrum anterior-posterior”. The results were exported to the EndNote 9X (Clarivate Analytics, Philadelphia, Pennsylvania) citation manager.

Eligibility Criteria

Inclusion criteria consisted of studies reporting outcomes for isolated type II SLAP repair done in the BC or LD positions. Studies reporting revisions, biceps tenodesis, concomitant rotator cuff lesion repair, Bankart repairs, and posterior labral repairs were excluded. Studies were stratified based on patient positioning for SLAP repair: BC or LD.

Study selection

Two independent reviewers (A.B and S.S) performed a literature search based on the PRISMA guideline (Preferred Reporting Items for Systematic Reviews and Meta-analyses) and reviewed the results. Studies were included if consensus was reached by the reviewers. The senior author (A.L) was consulted to resolve any disagreement on study inclusion. Titles and abstracts were screened in the first stage, followed by the full-text review of the eligible papers. Lastly, the reference lists of the included studies and review papers were manually screened for additional studies that may have been missed by the initial search.

Quality Assessment

The level of evidence of the included studies was assessed using the American Academy of Orthopedic Surgeons classification system for the orthopedic literature. The Methodological Index for Non-Randomized Studies (MINORS) checklist was used to assess the study’s methodologic quality.¹¹

Data Extraction and Statistical Analysis

Data obtained from the studies included preoperative and postoperative outcomes as means or mean changes, and standard deviations (SD) or P-values. We aimed to extract outcomes including the University of California at Los Angeles Shoulder Score (UCLA), Visual Analog Scale (VAS), Constant score, the American Shoulder and Elbow Surgeons Score (ASES), and range of motion (ROM). Each functional outcome measure was analyzed separately. The unit conversion was not necessary. Data were compiled into Comprehensive Meta-Analysis Software version 3 (Biostat Inc, Englewood, New Jersey) to perform the meta-analysis. The studies were grouped by patient positioning of BC versus LD.

This analysis took study effects into account, and a random-effects model was used for statistical analysis to calculate the risk ratio and 95% confidence interval. The null hypothesis was rejected if the P-value was less than 0.05. An important consideration in performing a meta-analysis is whether the effects found in the individual studies are similar enough to be confident that a combined estimate will be a meaningful description of the studies’ set. Considering the individual estimates of the treatment effects can vary by chance, it is important to evaluate whether there is more variation than expected by chance alone. This excessive variation is called heterogeneity. To address the proportion of sampling error versus the true effect, the heterogeneity was assessed using Q statistics and the degree of freedom to compute the P-value. If P-value was less than 0.05, the null hypothesis was rejected, indicating the variations in the true effects. The Q statistics were also utilized to compute the I² which indicates that the proportion of dispersion in the effect sizes is caused by true differences in the effect. If I² equals zero, it suggests that all dispersion in the effect sizes can be attributed to the random sampling error. The I² describes the percentage of total variation across studies due to heterogeneity rather than chance. Given that negative values of I² are put equal to zero, I² has a range between 0% and 100%. A value of 0% indicates no heterogeneity, and a larger value indicates increasing heterogeneity.

Results

Search Results

Databases were queried on April 24th, 2021, resulting in 8,010 records (Embase:1698, Scopus:2822, Web of Knowledge:2006, Cochrane:71, Pubmed:1413), and the manual bibliographic search found 16 papers. Duplications were identified and removed, and the records were screened by title and abstract. All articles published in the English language were available and assessed for eligibility. Of the 108 assessed full-texts, 23 papers were included for meta-analysis. Of these, 13 papers 12-24 were included in the BC group, and 10 articles 25-34 were included in the LD group [Figure 1].

Figure 1.

PRISMA flow diagram

Study Quality

The level of evidence of studies and the MINORS scores have been summarized in Table 1.

Table 1.

Study Characteristics and Patient Demographics

MINORS score	14	15	9	9	12	10	9	11	11	13	17	9	11		8	7	11	13	15	13	13	13	13	7	18	18	9
Female:Male	07:13	03:08	08:39	N/A	00:10	09:39	11:33	02:23	10:31	01:15	06:08	06:18	01:40		05:09	12:43	06:14	07:18	N/A	00:25	01:24	02:12	02:13	35:144	04:11	05:12	03:13
Number of Patients	20	11	47	34	10	48	44	25	41	16	14	24	41		14	55	22	25	15	25	25	14	15	179	15	17	16
Age (years)	35.7	31.8	36	34	31	33.1	33	36	32.9	28.8	34.2	22.7	24		28.4	39.7	45.2	40	58	23	36.4	43.4	41.6	31.6	29.66	28.83	24.2
Follow-up (months)	26	41.9	32.3	44.4	35	40.8	30.5	35	32	24	31.4	45.8	33		12.7	77	63.2	54	29	36.4	40.5	30.4	29.7	40.4	37	37	27.6
Country	Germany	Austria	USA	USA	Austria	USA	USA	USA	Korea	Singapore	Korea	Korea	USA		Italy	USA	USA	Canada	Turkey	USA	USA	Korea	Korea	USA	Spain	Spain	China
Journal	Acta Orthopaedica Belgica	BMC Musculoskelet Disord	J Bone Joint Surg Am	Am J Sports Med	J Shoulder Elbow Surg	J Shoulder Elbow Surg	Am J Sports Med	Arthroscopy	Knee Surg Sports Traumatol Arthrosc	J Orthop Surg (Hong Kong)	J Shoulder Elbow Surg	Am J Sports Med	Arthroscopy		Knee Surg Sports Traumatol Arthrosc	Arthroscopy	Orthopedics	Int J Shoulder Surg	Arch Orthop Trauma Surg	Am J Sports Med	Am J Sports Med	Knee Surg Sports Traumatol Arthrosc	Knee Surg Sports Traumatol Arthrosc	Am J Sports Med	Arthroscopy	Arthroscopy	Knee Surg Sports Traumatol Arthrosc
First Author	Kaisidis et al.15	Boesmueller et al.5	Brockmeier et al.6	Coleman et al.8	Ek et al.11	Friel et al.12	Levy et al.21	Samani et al.30	Yang et al.39	Zhu et al.41	Kim et al.17	Park et al.26	Rhee et al.29		Castagna et al.7	Denard et al.9	Denard et al.10	Trantalis et al.38	Kanatli et al.16	Neri et al. (<40)24	Neri et al. (≥40)24	Ok et al. (new)25	Ok et al. (old)25	Provencher et al.28	Silberberg et al. (1)32	Silberberg et al. (2)32	Yung et al.40

Study Characteristics and Patient Demographics

Overall, 815 participants were included comprising 378 patients in the BC group and 437 patients in the LD group. The mean follow-up duration was 35 months for the BC group and 44 months for the LD group [Table 1].

Clinical Outcomes

Five studies reported UCLA in the BC group and four studies in the LD group, all showed a significant improvement from preoperative to postoperative. The difference between BC and LD, however, was not statistically significant [95% confidence interval: BC=0.927-3.683, LD=1.649-4.560, Figure 2].

Figure 2.

Forest plot of UCLA using a random-effects model (Cochran’s Q: 0.612, P-value: 0.434)

Visual analog scale (VAS)

Eight studies in the BC group and five studies in the LD group reported pain VAS. All studies showed a significant reduction in the VAS score. However, the results were significantly better in the LD group [95% confidence interval: BC=0.542-1.447, LD=1.524-2.726, Figure 3].

Figure 3.

Forest plot of VAS using a random-effects model (Cochran’s Q:8.67, P-value:0.003)

Constant score

Five studies in BC reported a Constant score, while only two reported it in the LD group. All studies reported significant improvements. Although the improvement in the LD group was larger than in the BC group, the difference was not statistically significant [95% confidence interval: BC=0.624-1.258, LD=1.250-2.964, Figure 4].

Figure 4.

Forest plot of Constant score using a random-effects model (Cochran’s Q:6.255, P-value:0.012)

Six studies in the BC group and seven studies in the LD group reported the ASES outcome. All preoperative to postoperative improvements were significant. The LD group showed a greater improvement than the BC group, although the difference was not statistically significant [95% confidence interval: BC=0.507-1.442, LD=1.395-3.179, Figure 5].

Figure 5.

Forest plot of ASES using a random-effects model (Cochran’s Q:6.531, P-value:0.011)

Forward Flexion

Three studies in BC groups and eight studies in the LD group reported forward flexion. All studies in the BC showed significant improvements. Four studies of the eight studies in the LD group showed a reduction in forward flexion, of which two showed a significant reduction after surgery. Forward flexion measurements showed significant improvement in the BC group, but the improvement was not significant in the LD group [95% confidence interval: BC=0.369-0.708, LD=0.062-0.869, Figure 6].

Figure 6.

Forest plot of forward flexion using a random-effects model (Cochran’s Q:0.107, P-value:0.744)

External Rotation

In the BC group, two studies reported external rotation before and after surgery. The pooled effect of the two studies showed significant improvement in external rotation, while each individual paper could not show a significant change. In the LD group, seven studies reported external rotation before and after surgery. The pooled effect did not show a significant change from pre to postoperative external rotation, whereas one study even showed a significant reduction in external rotation [95% confidence interval: BC=0.019-0.371, LD=0.166-1.170, Figure 7].

Figure 7.

Forest plot of external rotation using a random-effects model (Cochran’s Q:3.041, P-value:0.081)

Abduction

Two studies in each group reported abduction. The two studies in the BC group showed significant improvements, and the pooled effect was significant. The two studies in the LD group showed a significant reduction in abduction, but the calculated pooled effect was not significant. [95% confidence interval: BC=0.330-0.820, LD= (-2.770)-0.313, Figure 8].

Figure 8.

Forest plot of abduction using a random-effects model (Cochran’s Q:5.128, P-value:0.024)

Discussion

This study aimed to compare type II SLAP repair outcomes when performed in the BC versus LD position. We pooled the outcomes in three domains: pain score, functional scores (Constant, ASES, UCLA), and ROM. Our results showed greater improvement in pain and functional scores in the LD position, while ROM was similar for both groups with the exception of abduction which favored the BC position.

We found a more remarkable improvement in pain in the LD compared to the BC position, which explains a higher functional score in the LD position. It has been reported that visualization of the glenohumeral joint is reduced in the BC position for instability and SLAP repair compared to the LD position.³⁵ It is possible that a more anatomic repair can be achieved with better visualization, possibly resulting in a better outcome. All three functional scores of ASES, Constant, and UCLA comprise the pain rating in the total score, showing a direct correlation between pain and functional scores.

Although the difference was statistically significant for VAS pain, the minimal clinically important difference (MCID) is 1.4 points after shoulder arthroplasty and 2.4 points after rotator cuff repair.^{36, 37} This value is more than the VAS difference between LD and BC in our study (1.13 points) although the MCID for pain after SLAP repair is not currently available in the most recent systematic review.³⁸ Functional outcomes have shown substantial improvement with time following a SLAP repair.³⁹ Intuitively, the more considerable improvement in pain and function in the LD group might be due to the longer mean follow-up (44 months) than the BC (35 months). We speculate that there may be no substantial difference between the LD and BS positions if the follow-ups were equalized.

Our results demonstrated a greater improvement in abduction following SLAP repair in the BC position, although all other ROMs were not significant. Few studies in both groups reported the ROM; hence, making these findings vulnerable to publication bias with bias in interpreting the results. Since the ROM is a domain comprising the UCLA and Constant scores, one would expect to see a direct correlation, which contrasts with the findings of this study. There are two studies in each group reporting abduction. The study of Castagna et al. is the shortest follow-up with 12 months, while other studies have a minimum of 2-year follow-up. The other Provencher et al. study included a military patient cohort, which is a different cohort from the general population and with athletes. Some studies have demonstrated lower outcomes and delayed return to duty in this population.^{40, 41} Although there was a slight decrease in LD and an increase in BC, the average numerical final abduction and forward flexion in all other studies are comparable, showing no clinically significant difference [Table 2].

Table 2.

Reported change in motion following an arthroscopic SLAP repair

Study	Position	Direction	Preop (degrees)	Final (degrees)
Friel 2010	BC	FF	160	180
Zhu 2018	BC	FF	129	139
Castagna 2014	LD	FF	168	166
Provencher 2013	LD	FF	164	159
Friel 2010	BC	Abd	156	179
Zhu 2018	BC	Abd	117	136
Castagna 2014	LD	Abd	91	85
Provencher 2013	LD	Abd	166	151

BC: beach chair; LD: lateral decubitus; FF: forward flexion; Abd: abduction

The study of Provencher et al.is the only one with a significant decrease in motion despite improved pain and function, and SLAP repairs were performed in the LD position in a military cohort. The results of this study might explain the bias in motion improvement. Among the included studies for ROM, Kanatli et al. had an eminent effect on the results. The study was on patients over 45 years of age in the LD position, and none of the patients experienced any complications.²⁸

The main limitation of this study is the lack of comparative studies and outcomes. Although most of the reported measurements were satisfactory for both positions, the technique (e.g., fixation type) and the materials were chosen based on the surgeon’s preferred position.⁶ Multiple factors may bias comparing the results of these case series, including the surgical technique, application of the regional block, use of the accessory portals, concomitant conditions, postoperative rehabilitation protocol, and patients’ compliance. Moreover, although the mean follow-up of both groups is comparable, there is still a bias when comparing the results.

Based on the findings of this systematic review and meta-analysis, both the BC and LD positions provide patients better outcomes following operative repair of type II SLAPs. While LD represented a better improvement in functional outcome measures, the BC position demonstrated better abduction with no other significant differences between both positions. An individualized approach to position selection concerning the patient’s complaint (pain vs. motion) as well as the surgeon’s discretion is recommended.

Funding:

The authors received no funding for this work.