Latissimus dorsi anterior to major transfers have been advocated in the setting of loss of external rotation and elevation in conjunction with reverse shoulder replacement. Reverse shoulder replacement is a prosthesis specifically designed for shoulders with poor rotator cuff function. In the vast majority of cases, some teres minor function at the minimum is maintained in shoulders destined for a reverse shoulder replacement. However, in certain circumstances there is complete loss of any external rotation, and a muscle transfer can be performed in order to restore some external rotation function. A reverse shoulder replacement in the absence of any rotator cuff function goes into obligate internal rotation with elevation. A minimum of external rotation strength is necessary in order to maintain the arm in normal rotation. The first tip is patient selection. Physical examination of active external rotation, external rotation strength and forward elevation should be just performed. A latissimus transfer is indicated in patients who cannot maintain their arm in neutral to at least a few degrees of external rotation. A lag sign is another physical examination finding which can indicate complete loss of rotator cuff function. The latissimus dorsi transfer is performed by first identifying and releasing the latissimus from its insertion on the anterior humerus. The arthroplasty is performed. The passage for the latissimus muscle is developed carefully and being mindful of the axillary nerve in particular. The latissimus is directed inferior to the nerve and around the medial and posterior aspect of the proximal humerus. Different ways of securing the transfer to the humerus have been described including bone tunnels and anchors. Often it is easier to place the anchors and/or the bone tunnels prior to inserting the humeral prosthesis. The latissimus is secured in the new position, enabling it to participate in external rotation. The value of this is difficult to clearly establish. Most studies are evidence level IV and there are no good comparative studies in a controlled patient population. This is a good option for shoulders with no active external rotation, but they may increase overall complication rate. Complications include dislocation, infection, and transient nerve palsy.

The treatment of proximal humerus fractures remains controversial. The literature is full of articles and commentary supporting one method over another. Options include open reduction and internal fixation, hemiarthroplasty, and reverse shoulder arthroplasty. Treatment options in an active 65-year-old are exceptionally controversial given the fact that people in this middle-aged group still wished to remain active and athletic in many circumstances. A hemiarthroplasty offers the advantage of a greater range of motion, however, this has a high incidence of tuberosity malunion or nonunion and this is a very common reason for revision of that hemiarthroplasty for fracture to a reverse shoulder replacement. One recent study showed a 73% incidence of tuberosity malunion or nonunion in shoulders that had a revised hemiarthroplasty to a reverse shoulder replacement. Progressive glenoid wear and erosion is also a risk after a hemiarthroplasty in the younger patient, especially someone who is young and active. In addition, studies show shorter operative time in hemiarthroplasty. The range of motion is highly dependent on proper tuberosity healing and this is often one of the most challenging aspects of the surgical procedure as well as the healing process. A reverse shoulder replacement in general has less range of motion compared to a hemiarthroplasty with anatomically healed tuberosities, however, the revision rate is lower compared to a hemiarthroplasty. (This is likely related to few were options for revision). The results after a reverse shoulder replacement may not be as dependent on tuberosity healing, however, importantly the tuberosities do need to be repaired and the results are significantly better if there is healing of the greater tuberosity, giving some infraspinatus and/or teres minor function to the shoulder. Complete lack of tuberosity healing forces the shoulder into obligate internal rotation with attempted elevation and this can be functionally disabling. Academic discussion is beginning surrounding the use of a reverse shoulder replacement in the setting of glenohumeral joint arthritis in a primary setting as it is believed that the glenosphere and baseplate may have greater longevity than a polyethylene glenoid. Along with this discussion, we will likely see greater application of the use of a reverse shoulder replacement in the setting of fracture for younger patients.

In general, open reduction internal fixation should still remain the treatment of choice in the setting of a fracture that can be fixed. However, a strong argument can be made that if an arthroplasty is necessary, a reverse shoulder replacement is the implant of choice.

Total shoulder arthroplasty is becoming increasingly common. A biceps tenodesis or tenotomy has become a routine part of the operation. There are several advantages to a tenodesis or tenotomy. First, the long head of the biceps tendon is routinely pathologic. One study has shown that there are differences in gene expression and mechanical properties in the long head of the biceps tendon in the setting of glenohumeral joint arthritis. Clinically, we often see inflammation, tearing, adhesions, or other pathology. Second, it is largely accepted that the long head of the biceps tendon has minimal function at the shoulder. The biceps muscle primarily functions at the elbow. Therefore, there is little downside to performing a tenodesis if there is a chance of it generating pain after surgery. Another major reason to perform a tenodesis or a tenotomy is that the technique of total shoulder arthroplasty requires a subscapularis takedown or lesser tuberosity osteotomy. The ligaments and tendon associated with the subscapularis contribute to the stability of the biceps tendon and after subscapularis takedown, it is unlikely that the tendon would remain reduced in the groove. In addition, it is part of a technique to incise and release the rotator interval, additionally creating scarring and/or instability associated with the biceps tendon. Given those reasons, this is a very common and reasonable routine part of the procedure of total shoulder arthroplasty.

A reverse shoulder arthroplasty has become increasingly common for the treatment of proximal humerus fractures. A reverse shoulder arthroplasty is indicated especially in older and osteopenic individuals in whom the osteopenia, fracture type or comminution precludes fixation. However, there are many other ways to treat proximal humerus fractures and many of these are appropriate for different indications. Percutaneous pinning remains an option in certain surgical neck or valgus impacted proximal humerus fractures with minimal or no comminution at the medial calcar. In general, a fracture that is amenable to open reduction and fixation should be fixed. Open reduction and internal fixation should be the gold standard treatment for three-part fractures in younger and middle-aged patients. Four-part fractures should also be fixed in younger patients. Hemiarthroplasty results are less predictable as they are very dependent on tuberosity healing. While a reverse shoulder replacement may be considered in patients with severe comorbidities, patients always have better outcomes in the setting of an appropriately reduced and stably fixed proximal humerus fracture.

Rotator cuff tendon healing has proven to be a substantial clinical challenge. There is significant interest in finding biologic augmentation methods to improve this healing process. Two currently available products include platelet rich plasma/platelet rich fibrin matrix and several commercially available extra cellular matrix (ECM) patches. Platelet rich plasma is a sample of an autologous blood which has been centrifuged to a concentration of platelets three to four times that of normal. Platelets contain multiple growth factors, many of which have been shown to be involved in all phases in tendon healing. An alternative is platelet rich fibrin matrix. This forms a fibrin matrix with the platelets embedded within. Growth factors are subsequently released as the fibrin is reabsorbed. There are only a few studies which look at the effectiveness of platelet rich plasma and fibrin matrix. Overall, there is no strong evidence to support its routine use in the setting of rotator cuff repair. Extra cellular matrix patches are used to reinforce the strength of the repair and offload the tendon. They also provide the potential to form a scaffold for new growth and differentiation and may at some point be a delivery vehicle for cells and growth factors. There are currently two prospective randomised studies evaluating ECM patches – one showed that the patch studied was actually harmful to repair and the second suggested there was some benefit in larger tears. While there is not a lot of strong evidence to support routine use, further research and development is necessary to maximise this strategy.

Peri-prosthetic fractures around implants in the proximal humerus can present substantial challenges. Most individuals who undergo upper limb arthroplasty tend to be osteopenic to begin with, and the anatomy of the proximal humerus does not provide an excess of bone to work with. Therefore, peri-prosthetic fractures pose difficulties to rotator cuff function and implant stability. There are multiple classification systems, but series are small and the classification does not always lead to treatment algorithms. Risk factors for humeral fractures after shoulder arthroplasty include endosteal notching, cortical perforation, varus malalignment, stem perforation, ipsilateral shoulder and elbow arthroplasties, and loose stems. Many of these risk factors are directly related to technical errors at the time of surgery. Poor exposure can lead to aberrant starting point and errors in reaming. Oversized prostheses can lead to cortical perforation or even stem perforation. Proper positioning of the patient on the table and surgical releases help avoid these technical errors. Peri-prosthetic fractures should be carefully evaluated radiographically for stability. Two important considerations: 1. Is the implant stable? 2. Is the fracture stable? Generally, if the implant is unstable, the implant must be revised. In the setting of a stable implant, many humeral fractures can be treated nonoperatively. Many fractures at or below the level of the tip of the implant can be treated as typical humeral fractures. Options for fixation include plates with cables or long stem prostheses which bypass the fracture. Displaced tuberosity fractures are treated with suture or wire fixation. Risk factors for a poor outcome include increased time to union, skin breakdown, and stiff shoulder.

Shoulder arthroplasty has experienced exponential growth in the past 10–15 years, largely due to improvements in anatomical design, increased application of technology to address various clinical pathology, and improved access to experienced shoulder surgeons. Glenohumeral arthritis has historically been the most common indication for a shoulder replacement, and glenoid wear has been the main concern with regards to longevity of the prosthesis. Attempts to improve glenoid components involve alterations in peg or keel configuration, as well as the introduction of metal backed constructs. Early experience with metal backed components led to very poor results with often catastrophic loosening and destruction of glenoid bone. Proximal humerus fractures are another common indication for a shoulder arthroplasty, and in these cases, tuberosity fixation and healing are the challenge precluding a consistently successful result. More recently, base plate fixation in the setting of a reverse shoulder arthroplasty has come to the forefront as a significant factor.

Trabecular metal technology has emerged as a compelling method of enabling powerful bone ingrowth to the surfaces of arthroplasty components. Trabecular metal is composed of tantalum. It is used to form a carbon scaffold which has a modulus between that of cancellous and cortical bone, thus has some flexibility when made into an independent construct. Vapor deposition onto arthroplasty surfaces provides a bone ingrowth surface. There is interest in utilizing trabecular metal for glenoid and tuberosity fixation in particular.

Trabecular metal proximal coated stems provide an ingrowth surface for tuberosity fixation in the setting of proximal humerus fractures. Long term results are still pending. Because the metal is much less stiff then other metals, trabecular metal has recently been used along the back of polyethylene glenoids. The original design had a problem with fracture at the base of the pegs. A redesigned component instituting a cruciate design was implemented, and is currently available on a limited release basis with promising early results. The use of trabecular metal on the deep surface of the reverse arthroplasty baseplate and the proximal aspect of the reverse stem has led to successful fixation, allowing cementless fixation of both the humeral and glenoid components.

Learning objectives of this presentation include:

Understand the mechanical characteristics of trabecular metal and its bone ingrowth characteristics.