Partial Rotator Cuff Tears
Managementof the partial thickness rotator cuff tears in the shoulder.
Whereare we now and where do we go? - Review of current literature
Writtern as a part of the application for BOSTAA and Arthrex Sports Medicine travelling fellowship 2014
Mr Santosh Venkatachalam
Controversy continues about the ideal method of treatment for partial thickness rotator cuff tears (PTRCT) of the shoulder. While numerous studies have been published about the outcomes following surgical treatment of these tears, there is still no consensus about the best way of treating them. The purpose of this paper is to review the current evidence and provide guidance to shoulder surgeons on the future direction in the management of PTRCT.
Although it is almost 90 years since PTRCT have been described , their optimal treatment remains a challenge. Partial thickness tears can be twice as common as complete tears but the complete tears tend to be more symptomatic than PTRCT. Approximately five to ten percent of patients with symptomatic shoulders have PTRCT . Hence it is not an uncommon condition to manage in a shoulder or sports clinic. Progression in technology with Magnetic Resonance Arthrography (MRA)  and shoulder arthroscopy (since early 1990s) has made it possible to diagnose these tears with high sensitivity and specificity. The threshold for operative repair of these tears has been lowered because of their poor biology and lack of healing potential. They can progress to higher thickness tears (80% tear progression over two years, around 30% to full thickness tears).
Thereis variation in the literature regarding causes , identification,classification, treatment options and outcome measures used in the managementof PTRCT.
Themost common accepted classification system  is based on the location oftears (bursal, articular,interstitial) and articular surface tears are graded based on the exposedarticular footprint (Normal footprint is assumed as 12 mm. Grade I-3mm, GradeII- 3-6 mm, Grade III- >6 mm).
In PTRCT, articular surface tears are at least twice as common as bursalsided tears . The most common tendon involved in articular surface tears is the supraspinatus  which could be due to the reduced tensile strength of articular surface of this tendon . Aetiology of a bursal sided tear is believed to be secondary to an external impingement from acromion , while the articular sided tear could be caused by occult instability, tensile overload or loss of humeral rotation (internal impingement especially in overhead athletes) .
Conservativetreatment like physiotherapy, painkillers and joint injections are options toconsider in the treatment of PTRCT. [3, 10]. The primary problem appears to bethat the natural history of this condition is unclear. Also, there is no high level evidence comparing the non-operative versus operative treatment of PTRCT.Hence it becomes difficult to definitively suggest that operative intervention alters the course of the condition and if so, the timing of this intervention is unclear.
Surgical options for failed conservative treatment in symptomatic shoulders include debridement of the tear, subacromial decompression, in situ repair of the tear and completion of the tear and repair. While there is evidence (majority of themare level IV) to suggest all these surgical modalities work, it still remainsunclear as to the ideal method of treating PTRCT.
Adding further to the confusion is the different outcome measures (UCLA score, Simple shoulder test, American shoulder and elbow society score, LInsalata score, Constant score, Japanese Orthopaedic Association score) utilised to report outcomes following intervention.
Huge impact of subjectivity on which the current classification system of size of PTRCT utilised relies on, heterogeneity of treatment options and utilisation of various outcome measures poses challenges to reaching conclusions based on literature evidence.
All published English literature regarding surgical interventions for PTRCT from January 1991 to March 2014 was searched in Medline, Ovid, and the Cochrane Register of Controlled trials. A summary of the interventions and their outcomes are described below.
Surgical debridement only
Studies(case series) on PTRCT treatment with surgical debridement of the tear only have reported good outcomes [11-20]. These have all been level IV evidence withpatient numbers varying from 19 to 111 patients and follow up between 23 to 101months. The classification system used for categorisation of tears has also varied in each of these series.
Debridement and decompression
The procedure of subacromial decompression combined with debridement[14,16, 17] also has been reported to have good outcomes in the management ofPTRCT (30-53 months follow up). However the scoring systems used in these studies have varied and outcomes of good/ excellent in individual scoring systems are not always comparable with each other..
There is also some recent contradicting evidence (with longer term follow up) suggesting only debridement or in combination with subacromial decompression may not be sufficient and some form of PTRCT repair is required .
Transtendon repair (insitu repair)
Arthroscopic trans tendon repair of PTRCT had improvement in shoulder scores following the surgical intervention [16, 22-28]. These studies included all grades of tears(I-III) making the interpretation of the outcome challenging. Concomitant procedures like subacromial decompression, biceps tenodesis or tenotomy can be confounding factors in evaluating the overall outcome.
Complete tear and repair
All studies in this category were level IV evidence and dealt with Grade III PTRCT[29-31]. Pain levels and satisfaction scores improved significantly in all patients suggesting this particular technique works in the treatment of PTRCT.
Therehave been two systematic reviews and three randomised control trials published inthe last four years about PTRCT.
One systematic review  about PTRCT concluded that an ideal surgical intervention could not be proposed based on the currently available evidence. Another systematic review  that compared the repair techniques in the treatment of articular PTRCT had 14 studies which met its inclusion/ exclusion criteria and all the studies were level IV retrospective case series. This systematic review (and it appears to be the general consensus as well with no strong evidence to support it) recommended that for articular PTRCT <50% thickness of the tendon, debridement and subacromial decompression was an option while >50% thickness tears repairing the tear (insitu/ complete the tear and repair) would be beneficial. It concluded that there was no single technique provided superior outcomes and recommended that further Level I and Level II studies are required to determine the optimal treatment of partial articular surface cuff tears.
Three recent RCTs [33-35] have concentrated on the repair technique for articular PTRCT (in situ repair versus complete and repair). None of these have found any difference between the two techniques but all of the RCTs reported that both techniques were safe, effective and comparable in terms of function and pain relief.
The current literature suggests that all patients improve with surgical treatment of symptomatic PTRCT irrespective of the surgical technique.
However,the challenges facing todays shoulder arthroscopic surgeon are to decide which method would be the ideal one that guarantees good outcomes for a particular patient. To answer this question, current evidence appears inadequate. Our approach to this condition needs to be refreshed before we begin to identify the best surgical intervention. We must go back to basics and first understand/appreciate the pathoanatomy of PTRCT, agree on a classification system to develop alogical sequence to approach this condition before applying rationale in the surgical decision making process.
This would include categorising the tears based on their location, size, aetiology and type of intervention. We would also need to identify the natural progression of the tears in a better manner. Moreover, other factors that should be strongly considered and are influential in the treatment decision are age, activity level, vocation, sports participation, duration of symptoms, and concomitant pathologies. Many of the studies in the literature have awide age range from 16 to 90 years. This indicates that the underlying aetiology can be different from intrinsic impingement to degenerative causes in these studies. We need to be more critical about the underlying cause of PTRCT and then correlate them with the outcomes so that it reflects the result of the actual intervention, limiting the effect of other variables/ confounding factors.
The Ellman classification  of articular surface PTRCT has its deficiencies since it assumed the normal foot print of supraspinatus tendon to be 12 mm but it is proven that this can be variable from 9.6 to 16 mm (mean medial to lateral width) on anatomical studies [28, 36-39].
If the method of determining the extent of PTRCT remains difficult/prone to errors, then the whole basis of treatment and measuring outcomes becomes imprecise. It is also proven that the inter-observer agreement of tear depth using an arthroscopic probe is poor .
There is general consensus that partial thickness tears involving>50% of the tendon thickness should be repaired [23, 28, 41]. There is bound to be selection bias if the basis of deciding treatment is determined by the size of the tear with higher grade partial tears undergoing cuff repairs and lower grade tears treated with debridement. It would become extremely difficult to interpret results of studies based on these criteria and reach conclusions.
With respect to the techniques employed to repair PTRCT (in situ versus complete and repair), the systematic reviews and randomised control trials suggest no difference in outcomes [3, 32-35]. At the same time, there is evidence in the literature to suggest that just subacromial decompression might be sufficient [11-20]. One needs to be vary of the fact that all repair techniques of PTRCT would involve an element of subacromial decompression. This could be a confounding factor as to analyse whether it is the repair that has helped or whether the subacromial decompression by itself would have a therapeutic effect and is sufficient for improving outcome.
Comparing in situ repair with complete tear and repair, anatomical and biomechanical studies recommend in-situ repair to be better than completing and repairing the tear .
As to why an in situ repair have not been proven better than complete the tear and repair technique in clinical studies, remains a question. This could be due to the poor understanding of the tear, incorrect in situ repair techniques and failure to consider concomitant pathology like SLAP tears and biceps pathology. It would make more sense to leave the intact sharpeys fibres of the cuff and repair the torn ones as in situ repair rather than cause more damage by completing the tear which is not anatomical. In situ repair has the advantages of maintaining tendon integrity / native foot print, normal length-tendon relationship of the cuff, provision of an intrinsic source of native tendon cells, leaving bursal side intact in articular surface tears and better biomechanical properties .
However, if not done properly, it can unbalance the tension in the remaining fibres, making it more painful, with longer recovery, failure of repair with medial rotator cuff failure and higher risk of stiffness . This can be of significance especially in overhead athletes who may be forced to abandon/ change their technique or sport secondary to the effects of the surgery. There is also a risk of over treatment of some athletes, since it is well documented that there can be asymptomatic changes in the rotator cuff of throwers shoulder whereas similar changes in a patient who is a non-throwercan be considered pathological. Other associated pathologies like scapular dyskinesia,muscle imbalance and rotation deficits (especially in overhead athletes) could contribute to the overall result. It is clearly evident that we need to refine our surgical technique in this particularly challenging patient population to aid them return to pre-morbidsports level consistently [44-47].
Completing the tear and repairing might have the advantages that it allows good mobilisation of the tendon from the scar tissue, debridement of the degenerated tissue with good preparation of the tendon footprint .
Another factor to consider in the management of these PTRCT is the assessment of the repair post operatively. It has been shown in the literature that although most patients have improved outcomes following surgical intervention, there is dearth of evidence on the assessment of the integrity of the repair. In other words, failure of the anatomical repair may not translate to a poor result clinically . MRA is proven to have high specificity and sensitivity in identifying PTRCT and also assessing the integrity of the cuff repair. This modality of investigation needs to be employed more often for reporting management and assessment of integrity of the repair of PTRCT in the literature.
There is lack of high quality evidence comparing integrity of repairs between articular and bursal PTRCT and the limited level IV evidence present is not consistent. In one study ,articular surface tears had a lower failure rate compared to bursal sided tears(9% versus 22%) in high grade PTRCT (although not statistically significant).In another study , bursal sided tears had comparable/ superior outcomes compared to articular surface tears but similar re-tear rates. This difference in re-tear rates in PTRCT based on their location could be due to the intrinsic differences in the pathogenesis of these tears.
Comparison of repair outcome, stiffness rates, recovery period and re-tear rates following repair to PTRCT and full thickness rotator cuff tears have failed to demonstrate any significant difference between the two groups .This suggests that the implants/ sutures used appear to be biomechanically strong to achieve satisfying outcomes irrespective of whether the tear is of full thickness or partial thickness. .
There appears to be less controversy regarding bursal cuff tears since the pathology is generally accepted to be due to extrinsic impingement and repairs are almost always supplemented with acromioplasty. In situ or complete and repair techniques are both described depending on the thickness, quality and location of the bursal tears. In fact, a recent prospective comparative cohort study suggested that the shoulder scores improve following simple subacromial decompression without repair of the bursal tear irrespective of its size.
Interstitial cuff tears are less commonly discussed in the literature probably because of lower incidence and lesser recognition. Shear forces between the parallel layers of collagen fibrils of the cuff can result in interstitial cuff tears with intact bursal and articular cuff surfaces. This would make it almost impossible to visualise unless there is a high index of suspicion on clinical and MRI investigations. Intraoperatively, various tests like sliding layers sign (probe slides over the cuff from the bursal surface causing the cuff to bulge on itself), bubble sign (spinal needle inserted into the cuff and injected with saline causes the cuff to bulge) and probe push test(on gentle push, the probe easily falls into the defect in the cuff) have been described. Failure to recognise these tears could contribute to some of the poor outcomes following shoulder arthroscopic procedures.
PTRCT remains a poorly understood topic. We are in need of a better classification system that is specific, reliable, has good intraobserver and interosberver agreement. This would help us make decisions as for the timing, technique and outcomes for conservative or surgical intervention. Once these issues are addressed, we need to design a robust randomised control trial with long term follow up, appropriate assessment of integrity of repair and standardised reporting outcomes to get some definitive answers.
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