Ultrasound guided platelet rich plasma or corticosteroid for supraspinatus tendonosis or partial tear: an observational study of clinical outcome

INTRODUCTION

The shoulder joint is a complex joint due to its vast range of movement. Upto 2.5% of the population presents with pain in shoulder, showing trend of rapid increase in prevalence with increasing age.¹ Rotator cuff pathologies are very common and are usually the main cause of pain.² More than half of all shoulder pains arise from rotator cuff tendinopathy (RC), most common being supraspinatus partial thickness tears and tendinosis.³

General guidelines suggest that the initial treatment of rotator cuff tendinopathy should be non- operative.^4,5 Conventionally, initial treatment includes physical rehabilitation, rest, and non-steroidal anti-inflammatory drugs.^6,7 Other methods used are extracorporeal shockwave therapy and barbotage.^4,8 CS, platelet-rich therapies (PRTs), hyaluronic acid, and botox injections have also been tried in such cases.⁹

Corticosteroids injections are more beneficial during the acute phase; however, they may cause tear of the tendon. Corticosteroids may also inhibit collagen synthesis.^10,11 A meta-analysis suggested that there may be improvement in symptoms with steroid injections in short term.⁹ CS injections decrease the proliferation of cells. They also affect the composition of collagen and extracellular matrix, inhibit inflammatory pathways, and cause an increase adipocyte differentiation and apoptotic cell death.^12-15 To add, these changes usually begin only after 24 hours and last up to 2 to 3 weeks, thereby causing a reduction in maximal load to failure. Concomitant local anesthetic use with corticosteroids may cause adverse effects in the soft tissues.¹⁶

The use of orthobiologics, like PRP and PRF, has become more popular recently.¹⁷ Platelet-rich therapies (PRTs) can be either platelet-rich plasma (RPP) or platelet-rich fibrin (PRF). Both of these can be either leucocyte poor or rich.¹⁸ Platelet rich plasma delivers high concentrations above physiological levels of growth factors in targeted area.¹⁹ Autologous platelets have been shown to be helpful in revascularization of the injured area. They also promote tendon healing by increasing growth of tendon cells, PDGF, and TGF and improve pain and function.²⁰ PRP injection therapies in different studies have been found to have a huge potential in rotator cuff tendinopathies as well as in other musculoskeletal disorders. In contrast to corticosteroids, no significant adverse effects have been found to be associated with PRP injections. Hence PRP may provide many benefits in soft tissue healing.²¹

The objective of the present study is to compare the clinical outcomes of ultrasound guided PRP and CS injections in supraspinatus tendinosis or partial supraspinatus tear (as confirmed by MRI).

METHODS

A prospective observational clinical outcome study was conducted in the department of orthopaedics of Base Hospital, Delhi Cantt. from September 2020 to March 2022. Ethical committee approval was taken from Institutional Ethical Committee, Base Hospital Delhi Cantt. Both treatment methods i.e USG guided PRP and CS were both being routinely used, a total of 100 patients (50 in PRP and 50 in CS group). The choice of type of intervention was jointly decided by the patient and the treating team who administered the intervention. Informed written consent was taken before including the patients in the study on a first come basis. Patients of both sexes between the ages of 20 and 50 years with positive clinical test for supraspinatus tendinopathy and MRI suggestive of supraspinatus tendinitis were included in the study. The exclusion criteria were prior fracture or surgery around the shoulder, full-thickness RC tear, anticoagulant therapy, prior history of local steroid and PRP injection in the past six months, bleeding disorders or pre-procedure platelet count less than 50,000, diabetes mellitus, cervical spondylosis, stiffness>6 months, concomitant involvement of other rotator cuff muscles, shoulder instability, frozen shoulder, osteoarthritis of acromioclavicular joint or glenohumeral joint and os acromiale.

A two-member team consisting of one orthopedic surgeon and one interventional radiologist diagnosed and administered intervention in all cases to avoid confounding bias. After establishing the diagnosis clinico-radiologically, they explained the patients in detail about both the treatment modalities (PRP and corticosteroid) and possible side effects. Patients either received CS or received 2.5 ml PRP with local anaesthetic (2.5 ml of 2% lidocaine) was administered under USG guidance (Figure 1).

The total volume of both injections was also kept the same. The procedure followed for injections are as follows.

CS preparation and application

Under sterile aseptic precautions single dose injection of 1 ml (40 mg) methyl prednisolone acetate with local anaesthetic (4 ml of 2% lidocaine) were prepared in a single use syringe. The area was cleaned and draped with sterile glove covered USG probe to guide injection site. USG guidance was provided by using a 1.7- to 10-MHz linear array transducer. A dorsolateral approach was used for injection in both groups under USG guidance and infiltration done.

PRP preparation

Approximately 30 ml blood was drawn from the patient into a syringe containing 5 ml sodium citrate. First centrifugation was done for 15 min (3,000 rounds per minute) which separated it into platelets poor and leucocyte rich plasma and platelets rich and leucocyte poor plasma. The platelets poor plasma was discarded. After another centrifugation procedure, the PRP was withdrawn. The PRP was then transferred from blood bank to procedure room (USG room) in test tube stand under aseptic and thermal controlled conditions immediately.

Post injection protocol for both groups

After the injection, all the patients were kept under observation for 30 minutes. During this period, they were approached about participation in the trial by one of the first three authors. The details of were explained to the patients and consenting patients matching the inclusion and exclusion criteria were divided into either of the two groups (group I for PRP or group II for CS) accordingly in the type of intervention administered.

Shoulders were immobilized using arm slings for next three days following which, patients were asked to follow a gentle rehabilitation exercise program which included passive as well as active range of motion exercises. Sport activities were avoided for 6 weeks. Pain was managed by acetaminophen or acetaminophen/tramadol (325/37.5 mg).

Sample size calculation

A power of 80% (Z1-β), a 5% (Zα) level of significance and a pooled standard deviation (SD) was used for calculating the sample size for the study. Using the data available from the study by Ibrahim et al in Egyptian population, the mean visual analogue score at months in PRP group and steroid group was 2.3 and 2.3 respectively.¹⁷ Assuming a true difference in means between the test and the reference group of 0 (i.e. 2.3-2.3) units, a pooled standard deviation of 1.7 units, the study would require a sample size of 50 for each group (i.e. a total sample size of 100, assuming equal group sizes), to achieve a power of 80% and a level of significance of 5%, for declaring that the first group is equivalent to the second group at ±1 units margin of equivalence.

Follow up and data collection

A total of 100 were recruited. Patients were followed up and compared at 6 weeks, 3 months and 6 months based on the VAS for shoulder pain, activity, satisfaction, the Oxford shoulder (OS) score, and the constant Murley (CM) score.

Statistical analysis

All data was analyzed by IBM-statistical package for social sciences (SPSS) version 21.0. Kolmogorov-Smirnov test was used to test normality.

Quantitative variables include unpaired t-test/Mann-Whitney test. Qualitative variables include Chi-square test/Fisher’s exact test.

P value was <0.05, which was statistically significant.

RESULTS

There was no significant difference in terms of the age group, gender distribution, residence, marital status, physical activity status, educational qualification, mean duration of symptoms, side affected and history of hypertension. Demographic data is given in Table 1 and 2. Shoulder contour of patients in both the arms were also similar. Pre intervention both the groups had similar distribution in terms of mild Joint line tenderness, and clinical examination.

VAS scores (pain, activity and satisfaction), OSS scores and CM scores before injection were similar. The only difference between the groups was a significantly higher proportion of patients in the PRP intervention arm (63.3%) had a history of overhead activity compared to the CS intervention group (36.7%).

Following intervention, the VAS pain scores between the CS and PRP groups at 6 weeks and 3 months shows no significant difference. The pain scores in the PRP group at the end of 6 months is significantly lower (p=0.04) than that of the CS group (Figure 2).

Both OSS (Figure 3) and CM score (Table 3) were significantly better (p=0.0) in the PRP group despite having minimal differences in the 6 weeks and 3-months score.

No significant difference was found in improvement of range of motion among the two intervention groups at baseline (pre- injection), 6 weeks and 3 months. Higher range of movements in flexion, abduction and external rotation, are seen at 6 months, in the PRP group following intervention. But only the differences in improvement in abduction were found to be statistically significant (Table 4).

*Statistically significant

*Statistically significant.

DISCUSSION

On reviewing available literature, it was found that PRP may have a positive role in the treatment for RC tendinopathy, although the interpretation of results was far from decisive, as different studies used different approaches to assess efficacy or used different products of PRP.^3,8,9 In their study on 58 patients with rotator cuff tendinopathy, after three months, Dadgostar et al, reported significant pain improvement in cases who received PRP injections compared with the corticosteroid group.²²

Shams et al on the contrary, showed better results with PRP only upto 3 months.³ However, they found no significant differences in the 6-months results. Similarly, von Wehren et al found early improvement with PRP, however no significant difference was found at 6 months of follow-up.²³

Despite difference in opinion as to the timing of the improvement, the present study tried to observe the clinical outcome of both PRP and CS group in a larger sample size in a tertiary care orthopedic centre and found similar results to studies by both Shams et al and von Wehren et al in concluding that PRP might be a better option as compared to CS injections.^3,23 Scapone et al reported significant pain improvement along with functional improvement and superior MRI outcomes.²⁴ In contrast, Kesikburun et al found no difference in PRP or saline injections over a follow up of one year.²⁵

In the present study, the results of PRP injection are similar to those of CS injections in the short term and better in the long term (6 months), hence, PRP can be used as an alternative to corticosteroid injections in patients with supraspinatus tendinosis or partial supraspinatus tear. Patients given corticosteroids injections are more prone to develop local and systemic complications especially on repeated use.²⁶ Local corticosteroid application causes weakness of the injected region of the tendon thereby increasing the chances of failure or rupture.²⁷ This weakening is present in the individual collagen fascicles. PRP is therefore, a relatively safe alternative that can be used multiple times with no significant side effects.^{3,13,16,24,26}

Various growth factors present in PRP have shown potential to increased synthesis of type I collagen and tenocyte proliferation.²⁸ PRP Injection into areas of musculotendinous injury in animals has been found to enhance the recruitment of cells for tendon healing during the early phases.²⁹ These factors together may explain the better longterm results in the PRP group due to increased healing potential compared to CS group.

The strengths of present study had a larger number of patients compared to the earlier studies by Shams et al and von Wehren et al.^3,23 The use of USG allows real-time examination, and the needle may be dynamically viewed as it approaches the target. The needle can be observed as an echogenic structure along its whole length.³⁰ However, some studies show no significant difference between USG-guided and landmark-guided injections.

In addition to the intervention, other factors also affect the recovery of patients. The most important of these are physical activity and oral analgesics. Since both the treatment groups received similar post procedure instructions regarding physical therapy and medications, effects of these variables on recovery were drastically reduced.

The limitations of the study are that it was conducted in a single centre thereby limiting the generalization of the findings. Secondly, despite the best efforts, a significant difference in the history of overhead activity was seen between the treatment groups. Whether that could have in any way affected the study results could not be evaluated within the study parameters. Finally, the study compares a single injection of PRP with CS. Previous data suggests better improvement with multiple PRP injections as compared to a single PRP injection, and thus the actual benefits of PRP, in the long term, may have been underestimated in the study.

CONCLUSION

Both corticosteroids and PRP group showed improvement in all the parameters in our study however the PRP group on 6 month follow up had significant reduction of pain as evident by improved VAS score and functional improvement and quality of life improvement as evident by Oxford shoulder score and constant Murley score. There is significant improvement in abduction with PRP group on long term follow-up.

PRP should therefore be considered as a viable option to treat supraspinatus tendinopathy/partial tear as it is cheap, readily available modality using patients own blood which is more acceptable to patient and also safe to individual especially where complications related to corticosteroids are anticipated. Ultrasound guided procedure can be used to enhance the accuracy of injection.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: The study was approved by the Institutional Ethics Committee

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