Introduction

Since we as physiotherapists frequently encounter patients with musculoskeletal problems requiring tissue healing and adaptation, we must be aware of the healing processes that occur inside the body and how various factors are influencing these processes. Smoking is a factor that decreases tissue blood perfusion and collagen synthesis, which can significantly alter and impair tissue healing. Most people are well aware of the detrimental effects smoking can exert on their bodies. People know that smoking can cause cancers to develop, in part because of increasing health knowledge and campaigns. However, many patients are unaware of the negative effects of smoking on tissue healing and its influence on pain outcomes. This study provides insight into smoking and supraspinatus tendon repair.

Methods

A retrospective cohort study was conducted to determine the impact of smoking and supraspinatus tendon repair outcomes. The study used prospective data collection at an orthopedic department in Hong Kong. Patients scheduled for primary arthroscopic rotator cuff surgery after a (reparable) supraspinatus tendon tear were included when MRI identified an intact repair.

Their baseline assessments were retrospectively reviewed but prospectively collected. Baseline assessments two weeks before the surgery included:

• Demographic data
• Medical history including smoking status, the presence or absence of diabetes mellitus, hyperlipidemia, and obesity
• Pain intensity measured through the 0-10 visual analog scale (VAS)
• American Shoulder and Elbow Surgeons (ASES) score functional assessment
• Physical examination of the shoulder

Smoking was defined as any type of inhalation of the fumes of burning tobacco and was recorded regardless of the amount of tobacco consumed.

The surgery consisted of a standard arthroscopic repair of the supraspinatus tendon and necessary concomitant procedures such as biceps tendon repair or acromioplasty.

The patients followed a standard physiotherapy rehabilitation protocol postoperatively. They were instructed to wear an abduction brace to immobilize the shoulder for 6 weeks. On the seventh week after the surgery, assisted active mobilization was initiated. At week 13 postoperatively, free active movements were initiated. Passive stretching and muscle strengthening were performed and continued up to 9 to 12 months after the surgical procedure.

The primary outcome measures were the postoperative pain score obtained through the VAS, the functional status of the shoulder measured with the ASES score, and active forward flexion of the shoulder. These outcomes were assessed at 2 years following the surgery. The Minimal Clinically Important Difference (MCID) of the ASES is reported to be 15.2 points based on the anchor method and 26.3 points when considering the Minimal Detectable Change (MDC).

Results

In total, 100 patients with a minimum follow-up of 2 years were analyzed. At this time, they also had a reassessment MRI scan at a mean of 18.5 months (+/- 11 months) after the operation. Twenty-two smokers and seventy-eight non-smokers were identified.

When analyzing the whole cohort it appeared that in thirteen patients, a full-thickness retear of the repaired supraspinatus tendon was found. Out of 22 smokers, 5 smokers had a retear (23%) while 8 non-smokers out of 78 had a retear (10%). Significant improvements were observed in pain and functional status at 2 years following the surgery for the whole cohort.

ASES improvements revealed values exceeding the MCID for both groups. Yet when the MDC is considered based on the study by Malavolta et al. 2022, only the non-smoking group exceeded the minimal clinically important difference of 26.3 points. The active forward flexion range of motion did not improve in those who had a full-thickness retear at the 2-year follow-up.

The univariate analyses found several potential associations between the covariates and the 2-year outcomes. When the linear regression analysis was run, only the following associations between the covariates and the 2-year outcomes were found:

• The regression analysis of potential associations between the 2-year clinical outcomes and the covariates revealed that smoking was the only significant predictor for poorer pain scores at 2 years. 
• The same was found for functional outcomes: smoking was the only factor significantly predicting poorer functional ASES outcomes after 2 years. 
• Regarding the forward flexion range of motion, the presence of a retear of the supraspinatus tendon was the only significant predictor of worse 2-year forward flexion range of motion.

Intact supraspinatus tendon after repair

When looking at those with an intact supraspinatus tendon after repair, significant improvements were observed in VAS and ASES scores, irrespective of smoking status.

• However, the non-smoking group achieved significant differences in active forward flexion from 115° to 161°, while no significant difference was observed in smokers’ active forward flexion from baseline to the 2-year follow-up.
• 99% of non-smokers achieved the minimal clinically important difference in VAS scores while only 82% of smokers did. This means that non-smokers were 14.6 times more likely than smokers to achieve the MCID for the VAS pain score at 2 years.
• 98% of non-smokers achieved the MCID for the 2-year ASES scores compared to 71% of smokers. This means that non-smokers were 24 times more likely to reach the MCID at 2 years.
• 90% of non-smokers achieved a minimum active shoulder forward flexion range of motion of 150° while 71% of smokers did. Non-smokers had a 3.8 more chance to have at least 150° of shoulder forward flexion range of motion at 2 years.

Matching smokers and non-smokers with intact repair:

Seventeen pairs could be matched with no differences in tear size, tear retraction and workers’ compensation status. They did, however, differ in terms of sex and body mass index. This subgroup analysis revealed that the 2-year pain score and ASES function score were significantly better in the non-smokers. Ninety-four percent of non-smokers achieved the MCID at 2 years for VAS compared to 82% of smokers. The same percentage of non-smokers (94%) achieved the MCID for ASES at 2 years compared to 71% of smokers.

Cuff Retear:

Thirteen patients had a full-thickness retear of the supraspinatus. Out of 22 smokers, 5 smokers had a retear (23%) while 8 non-smokers out of 78 had a retear (10%). At baseline, they had comparable pain scores, ASES scores and active forward shoulder flexion range of motion. Two years after the operation, the pain score in smokers was 3 compared with 1.9 in non-smokers. The 2-year ASES scores in smokers were 63.3 compared with 70.6 in non-smokers. The 2-year active shoulder flexion range of motion in smokers was 110° and 129° in non-smokers respectively. Thirteen percent of the non-smokers had a 2-year persistent pseudoparalysis (defined as) compared to 40% of smokers. 38% of non-smokers achieved the MCID for active forward flexion range of motion at 2 years, compared to only 20% of smokers.

Questions and thoughts

The current paper analyzed how smoking and supraspinatus tendon repair are related. A 13 percent retear rate in people undergoing surgery to repair their torn supraspinatus was found for the whole cohort, yet it appeared that more retears (23%) occurred in smokers compared to non-smoking participants (10%).

Analyzing the whole cohort found significant improvements in pain scores and functional outcomes at 2 years. An improvement in forward flexion range of motion was only observed in participants without a retear. The regression analysis showed that smoking was associated with worse pain and function at 2 years and the presence of a retear was associated with worse forward flexion range of motion at 2 years.

When the repair was intact at 2 years, it appeared that non-smokers had significantly improved in forward flexion range of motion from 115° to 161° while in smokers no difference was observed. More non-smokers achieved the MCID for pain, function, and forward flexion range of motion compared to smokers. This means that even if the repair was intact, smokers had more chance of having worse outcomes compared to non-smokers.

Participants with a retear of the supraspinatus at 2 years reported more pain, worse function, and forward flexion range of motion when they were smokers compared to non-smoking participants. Although this was only analyzed in a minority (13 retears) and no hard conclusions can be drawn from this exploratory analysis, this reveals a relevant potential association to consider about smoking and supraspinatus tendon repair.

This info might be relevant to share to fully inform people undergoing or who had undergone such surgery recently who present to physiotherapy. This impact of smoking and supraspinatus tendon repair retear risk is important to add to your prognosis but can also be relevant into helping someone quit smoking.

We can not make any decisions about smoking cessation in the name of the patient of course. But I think that sharing this information when you patient is open to think about the impact of smoking might be an important part of our guidance. Especially considering the amount of time we get to spend on a consultation. Pignataro et al. 2012 published a paper about the role of physiotherapists in smoking cessation. They indicate that “The myriad effects of smoking on cardiopulmonary, vascular, musculoskeletal, neuromuscular, and integumentary impairments clearly indicate an essential obligation for physical therapists and physical therapist assistants to play a greater role in tobacco cessation in order to enhance treatment outcomes and advance prevention.”

Especially when you know that up to 60% of current smokers would like to quit but are held back by their addiction, providing someone with the correct advice may be a small push to get the dice rolling. We might not be trained to guide smoking cessation but we can at least inform and refer in case the patient is open for behavioral change.

Talk nerdy to me

This study sheds light on the associations between smoking and supraspinatus tendon repair and retear risk, but also on the risk of potentially worse outcomes in smokers even with intact repairs. A relevant note to add is that some of the subgroup analyses were held in relatively small subsets of patients. This may have led to reduced power and may have impacted the conclusions. Yet, this study gives us important insights in the relationship between smoking and supraspinatus tendon repair outcomes.

A limitation lies in the observed differences between smokers and non-smokers in age, sex, body mass index, and involvement in workers’ compensation issues at baseline. This may endanger the conclusions and should lead to analyses in better-balanced populations. The authors have unfortunately not run additional subgroup analyses to see the impact of this inequity at baseline.

Luckily only 22 smokers were included in the study, but this may also be a potential limitation. Since the analyses about smoking and its effects could only be run in 1 out of 5 in this sample, this may have created an underpowered sample from a methodological point of view. But of course, from a healthcare perspective, we can only be happy about having “only” 20% smoking participants as fewer would always be better!

However, by running a subgroup analysis of matching pairs, the authors have tried to overcome this issue of unbalanced groups. Nevertheless, this gives us interesting insights, but we should be aware of the reduced power this creates in the analyses.

Take home messages

This study found negative associations between smoking and supraspinatus tendon repair outcomes. Highlighting the negative impact of smoking on retear rates as well as worse function, pain and range of motion after 2 years should raise awareness of the detrimental effects smoking has on tissue healing, even after surgical repair. Smokers with intact repair had worse pain and functional outcomes compared with non-smokers, emphasizing that even when surgical repair was successful, more negative outcomes were observed.

Reference

Yau WP. Smokers Achieved Minimal Clinically Important Difference for Visual Analog Scale and American Shoulder and Elbow Surgeons Scores at a Lower Rate Than Nonsmokers Even When Repaired Supraspinatus Tendons Were Intact on Postoperative Magnetic Resonance Imaging. Arthrosc Sports Med Rehabil. 2024 Feb 13;6(2):100877. doi: 10.1016/j.asmr.2023.100877. PMID: 38379600; PMCID: PMC10877171.