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Reverse geometry configuration total shoulder replacements are in widespread use for the treatment of patients with rotator cuff deficient shoulders but particularly for those with arthritic change so called ‘cuff tear arthropathy’. Such implants have also been used in the management of patients with unreconstructable proximal humeral fractures, a technique which has been described on Orthoracle at https://www.orthoracle.com/library/lima-smr-reverse-total-shoulder-replacement-for-proximal-humeral-fracture/
The design rationale in replacing a prosthetic ball on the glenoid (the glenosphere) and a socket on the humeral side in a semi-constrained construct, medialises the centre of rotation and increases the moment arm on which the large deltoid muscle can work, in the absence of the rotator cuff tendons which normally insert around the proximal humerus.
Many Orthopaedic companies have developed such shoulder replacement implants. In this case, I am using the stemless humeral implant on the reverse geometry system from the Italian company Lima. The stemless humeral component is constructed on a 3D printer to create a single piece of trabecular titanium. Hip surgeons have used the same trabecular titanium for successful reconstruction of the hip acetabulum with impressive bony ingrowth of the implant. In the shoulder, if the patient’s proximal humeral metaphyseal bone is not too soft then impaction of the trabacular titanium core humeral implant gives excellent primary fixation and promotes future bone ingrowth securing the platform component. This is a bone preserving procedure avoiding the need to use an intramedullary stem. The same humeral core component is used for anatomical total shoulder replacement and this facilitates revision of an anatomic replacement to reverse one. It is very straightforward to switch the articulating components leaving the glenoid baseplate and humeral core implants, which should be solidly fixed to bone, in place.
The patient in this case is an 80 year old female who presented with pain and dysfunction in her non dominant shoulder. Clinical assessment and investigations revealed the diagnosis of glenohumeral osteoarthritis with a thin and weak rotator cuff. She had exhausted conservative measures and felt that her shoulder was bad enough to consider major arthroplasty surgery.
INDICATIONS
Cuff tear arthropathy is the prime indication for this operation. Whilst such reverse geometry arthroplasty has historically been reserved for an older population, I would consider it in any patient over the age of 60. In patients with osteoarthritis and poorly functioning or thin rotator cuff insertion, an anatomic configuration total shoulder replacement is likely to have poor outcome. In such cases it is worth considering sacrificing the superior rotator cuff and using a reverse geometry implant.
Patients with rheumatoid arthritis may also be considered for a reverse shoulder replacement as the natural history of their rotator cuff insertion is of poor function and degenerate tears.
All patients considered for a stemless humeral implant must have their proximal humeral metaphyseal bone assessed with cross-sectional imaging by MRI or CT scan. Whilst patients with acute proximal humerus fractures may be managed with a stemmed reverse shoulder replacement the likely deficiency in the proximal humeral metaphysis is a contraindication to stemless humeral implant.
SYMPTOMS & EXAMINATION
Patients usually present with gradual insidious deterioration in shoulder function and increasing pain. They will describe dysfunction, an inability to raise their arm and weakness with any lifting or loading of the shoulder. They will describe deep-seated pain within the shoulder girdle, perhaps radiating down the arm. On occasions there may be some swelling in comparison with the opposite shoulder indicating the presence of a joint effusion. They may describe previous history of an injury to the shoulder but often there has been complete absence of trauma. Usually the symptoms have come on gradually over a number of months or even years. Night pain is often a feature and they may describe crunching or clicking within the shoulder.
Clinical examination is important to compare both shoulders looking for symmetry, with respect to swelling and muscle wasting. Active and passive range of motion should be assessed and it is most likely that clinical assessment of rotator cuff strength reveals marked weakness. Neurological status in the upper limb is particularly important in documenting axillary nerve sensory function and the motor function of the deltoid muscle. I assess this by asking the patient to actively lift the flexed elbow away from their side, whilst palpating over the deltoid muscle to feel for contraction. The complete inability to elevate the neurologically intact arm due to rotator cuff weakness is referred to as ‘pseudoparalysis’. It is important to assess range of motion in their cervical spine, as well as elbow, wrist and hand function on the side in question. As with any patients considered for surgical management, their past medical history and comorbidities, including medication, should be taken into consideration and carefully documented.
IMAGING
Plain Xrays are mandatory and ideally these should be 3 views: AP, lateral and axillary or modified axial views. I recommend MRI scanning in all patients undergoing shoulder replacement and I use this to confirm my clinical findings with respect to the rotator cuff deficiency. It is important to look at subscapularis and compare this with clinical findings as I will try to preserve subscapularis or certainly repair it if it needs to be taken down to gain access to the shoulder. It is also possible to estimate adequacy of bone stock on MRI scan both within the glenoid and the humeral head to predict any potential concerns with respect to fixation of the metal components on both sides of the joint. Presence of geode cysts in either site may be picked up on the MRI when not easily seen on plain radiographs. Such finding may influence preoperative planning such as implant choice or need for bone grafting.
ALTERNATIVE OPERATIVE TREATMENT
Patients with rotator cuff deficiency and minimal arthritis could be considered for arthroscopic assessment of the shoulder, with a view to rotator cuff repair. Such repair surgery could also be performed as an open operation. If repair of the rotator cuff tears is technically not possible, then surgeons have considered debridement, tuberoplasty of the exposed greater tuberosity, in combination with long head of biceps tenotomy, or release of the suprascapular nerve. More recently, some surgeons have had success with interposition patch grafting of the rotator cuff tendon deficiencies, or more recent techniques, such as suprascapular reconstruction or insertion of an absorbable balloon spacer into the subacromial space, to depress the human head into the glenoid and facilitate physiotherapy management in strengthening the deltoid muscle. Traditionally, hemiarthroplasty replacing the proximal humerus would be considered in patients with arthritis but in absence of rotator cuff tendons or indeed poor function, this has notoriously poor outcome. Extended humeral heads on such implants whether stemmed or resurfacing were historically considered to allow prosthetic material to articulate with the undersurface of the acromion. These were known as cuff tear arthropathy or CTA implants.
NON-OPERATIVE MANAGEMENT
As with all patients considered for any joint replacement surgery, conservative non-operative management should have been exhausted. Such treatment would include education of the patient as to their condition, suitable oral analgesia and anti-inflammatory medication, taking into account their medical comorbidities, and physiotherapy to optimise their function. Therapists will concentrate on an anterior deltoid strengthening program, which can be very successful in a motivated patient to improve range of motion, function, strength and hence reduce pain. Some doctors will consider steroid and local anesthetic injection to the shoulder, which can certainly help with acute inflammatory synovitis or arthritis. In my practice, we use ultrasound guided suprascapular nerve blocks with local anesthetic instilled into the suprascapular notch around the suprascapular nerve. This can be very beneficial in helping shoulder pain and then allowing a deltoid function to improve. In combination with physiotherapy exercise program, this can be very effective. If patients get good transient benefit from guided local anesthetic blockade of the suprascapular nerve, then they can be considered for percutaneous ablation of the nerve, using either a radio-frequency or a cryoablation probe. Studies are ongoing as to the effectiveness of such treatment but should be considered in the non-operative management of such patients.
CONTRAINDICATIONS
General medical health and comorbidities must be taken into consideration in any patient being treated surgically for arthritic conditions. Patients must be able to comply with relatively straightforward physiotherapy in the post-operative period and ongoing rehabilitation instructions to optimise their function. In patients with significant medical comorbidities then a multidisciplinary approach with a pre-operative assessment team, often lead by a senior anaesthetist, is recommended. Dysfunction of the deltoid muscle due to complete axillary nerve palsy is a contraindication to reverse geometry shoulder as the biomechanics of the implant are reliant on function of the deltoid muscle. Relative contraindications are lack of bone stock within the glenoid and scapula but this can be addressed with either a bone grafting techniques or use of augmented or custom-built implants. Such techniques are not described here.
The procedure is performed under general anaesthetic usually supplemented with interscalene local anaesthetic nerve block, performed by the anaesthetist. The patient is placed in the semi-sitting beach chair position, with the operated arm on a moveable narrow armboard. It is often appropriate to perform a social wash of the affected shoulder and axilla prior to routine skin preparation. Unless there are contraindications, I use Flowtron intermittent calf compression during surgery to reduce the risk of thromboembolic disease. Intravenous antibiotics are administered by aneasthetist. The skin is prepared using Chlorhexidine solution, starting with the hand and preparing the whole of the upper limb and shoulder, across to the patient’s midline. Standard adhesive drapes are used to protect the patient’s airway tubing and to allow adequate exposure for approach to the shoulder from an anterior incision. With the help of a company representative, the nurses should be familiarised with the sets required for shoulder arthroplasty. I also use a standard set of shoulder retractors which significantly facilitate the operation.
General points
• The surgery is primarily performed for pain relief, function can improve but it is often secondary to a reduction in pain –allowing improved Deltoid function.
• Patient progress and outcome will ultimately depend on the condition of the joint and soft tissue pre-operatively.
• Improvement can continue for 18-24 month’s post-operatively, it is therefore important to encourage patient to continue with rehabilitation until no further improvement.
• Aim of rehabilitation is good quality of movement, and maximal function, however in this group of patients increased scapula motion is to be expected and maybe encouraged,
• Don’t sacrifice quality of movement and function for ROM
• The principles of the Deltoid Rehabilitation Programme for irreparable rotator cuffs should be utilised.
Precautions
The underlying pathology is one of chronic degenerative rotator cuff rupture; it varies from patient to patient as to what if any rotator cuff remains intact. If any tendons were repaired then this will be stated in the op notes and the rehabilitation will be guided by this.
Repetitive overhead activities and loaded activities above shoulder height may be limited long term and should not be forced with rehabilitation.
Lifting weights above shoulder height with more than 2-4 kg should be avoided unless otherwise instructed by the surgeon.
Hand behind back (HBB) should not be forced and may not be regained There is likely to be a chronic deficit in rotator cuff strength, particularly in ER.
Immobilisation
• Patient to wear sling for 3 weeks 24 hours a day, only removing for physiotherapy exercises • At 3 weeks, start to wean out of sling but to continue wearing at night for a further 3 weeks
• Total sling usage – 6 weeks
Post-Operative
0-6 weeks: Pendular exercises; Active assisted ER to neutral (ONLY IF THERE IS NO SUBSCAPULARIS REPAIR); Active assisted elevation in supine as comfort allows – consider use of table slides or walk backs
3 weeks: Gradually wean out of sling – light activities only (weight of a cup of tea within the field of vision, short lever)
6 weeks: Start to increase ER, as ER increases gradually increase elevation ROM; Active assisted exercises progressing to active exercises – utilise short lever, supine & CKC if appropriate; Don’t force HBB position; No long lever open chain exercises until 8 weeks
8 weeks: Consider use of the principles of the Deltoid Rehabilitation programme Sub maximal isometrics in neutral – avoiding any repaired tendons
12 weeks+: Isometrics in variable starting positions; Progressing to resisted through range strengthening – consider weight of arm, varied starting position & functional weights as well as theraband. REMEMBER FUNCTIONAL GOAL and the underlying pathology is massive irreparable rotator cuff tear
Ultimate aim is function rather than anatomical range of movement.
The SMR reverse shoulder prosthesis in the treatment of cuff-deficient shoulder conditions. S Young, N Everts, C Ball, T Astley, P Poon. J Shoulder Elbow Surg. 2009 July;18(4):622-626
Mid-term results of a metalbacked glenoid component in total shoulder replacement. A Castagna, M Randelli, R Garofalo, L Maradei, A Giardella, M Borroni. J Bone Joint Surg [Br] 2010;92(10):1410-1415
Biomechanical evaluation of different designs of glenospheres in the SMR reverse shoulder prosthesis: micromotion of the baseplate and risk of loosening. P Poon, J Chou, D Young, S Malak, I Anderson. Shoulder & Elbow. 2010.2:94-99
Results of a stemless reverse shoulder prosthesis at more than 58 months mean without loosening. R Ballas, L Begun. J Shoulder Elbow Surg. 2103 September; 22(9):e1-e6
Clinical and radiological outcome of the Total Evolutive Shoulder System (TESS) reverse shoulder arthroplasty: a prospective comparative non-randomised study. B Kadum, S Mukka, E Englund, A Sayed-Noor, G Sjoden. Int Orthopaedics. 2014 May; 38(5):1001-1006
The TESS reverse shoulder arthroplasty without a stem in the treatment of cuff-deficient shoulder conditions: clinical and radiographic results. P Teissier, J Teissier, P Kouyoumdjian, G Asencio. J Shoulder Elbow Surg. 2015 January; 24(1):45-51
Reverse shoulder arthroplasty with a cementless short metaphyseal humeral implant without a stem: clinical and radiologic outcomes in prospective 2- to 7-year follow-up study. O Levy, A Narvani, N Hous, R Abraham, J Relwani, R Pradhan, J Bruguera, G Sforza, E Atoun. J Shoulder Elbow Surg. 2016 August; 25(8):1362-1370
Short to mid-term results of stemless reverse shoulder arthroplasty in a selected patient population compared to a matched control group with stem. P Moroder, L Ernstbrunner, C Zweiger, M Schatz, G Seitlinger, R Skursky, J Becker, H Resch, R Krifter. Int Orthopaedics. 2016 October; 40(10):2115-2120
Reference
- orthoracle.com
