Proximal humeral fractures (PHFs) account for approximately 4-10% of fractures in the elderly and are second only to hip and distal radius fractures in terms of incidence. Approximately 15% of these patients require surgical treatment, including fracture fixation and shoulder arthroplasty. The clinical prognosis after surgery depends on the site and extent of fracture displacement, damage to the humeral glenoid joint, and risk factors such as osteoporosis.
In fact, most patients can regain the original mobility of the shoulder joint, but the postoperative complication rate is as high as 40-60%. Ischemic necrosis of the humeral head (AVN) is the most concerning complication, as it can cause chronic pain, limb motion dysfunction, and the need for reoperation.
Shoulder arthroplasty is indicated for the treatment of comminuted three-part fractures and most four-part fractures of the humerus because of the high risk of nonunion of the humeral tuberosity and ischemic necrosis of the humeral head. Hemiarthroplasty is the most commonly performed surgical option, but its efficacy is influenced by the healing of the humeral tuberosity fracture fragment, so increasingly clinicians are preferring reverse shoulder arthroplasty for these fractures.
Professor Grant H. Garcia reviewed the staging of proximal humeral fractures and presented the surgical indications and contraindications for hemiarthroplasty and reverse shoulder arthroplasty in an article published in Techniques in Orthopaedics in 2013.
The more commonly used clinical staging of proximal humerus fractures is the Neer staging. The Neer staging is based on the four anatomical sites of the humerus, namely the lesser tuberosity, greater tuberosity, humeral head and proximal humeral stem, and the degree of displacement between them, i.e., displacement >1 cm (or greater tuberosity displacement >0.5 cm) or angular deformity >45°.
Neer staging of proximal humeral fractures
Understanding the structure of the humeral glenoid joint is important in the treatment of proximal humeral fractures. The greater tuberosity of the humerus is displaced posteriorly and medially by the rotator cuff muscle group, the lesser tuberosity is displaced medially by the subscapularis muscle, and the humeral stem is displaced medially by the pectoralis major and abducted by the deltoid muscle.
Direction of the deforming forces applied to the proximal humerus after fracture
The arteries supplying the humeral head are the posterior rotator humeral artery, the anterior rotator humeral artery and its terminal branch arch artery. It can affect the efficacy of incisional internal fixation and hemiarthroplasty for proximal humeral fractures. Recent studies have shown that the anterior rotator humeral artery supplies 36% of the humeral head, while the remaining 64% is supplied by the posterior rotator humeral artery. This finding has changed the treatment of proximal humeral fractures and has guided clinicians to fix the fracture site by incision and repositioning.
The posterior rotator humeral artery is not immediately adjacent to the proximal humerus and is therefore less likely to be injured during fracture, whereas the anterior rotator humeral artery is contoured to the proximal humerus and is easily injured during fracture.
Indications for hemi-shoulder arthroplasty
The risk factors for ischemic necrosis of the humeral head are important in the selection of the surgical approach, and Professor Boileay’s study showed that the probability of ischemic necrosis of the humeral head in two-part fractures of the proximal humerus is <10%, whereas in three-part fractures it is 10%-25%. In four-part fractures, the probability of ischemic necrosis is as high as 60%, and when combined with a displaced fracture, the probability of ischemic necrosis of the humeral head is 80%-100%. Therefore, most surgeons choose hemiarthroplasty for four-part fractures.
However, the probability of ischemic necrosis of the humeral head is only 25-30% for proximal humeral exostosis compression four-part fractures because there is no significant damage to the intervening soft tissues. It has also been suggested that hemiarthroplasty should be used for proximal three- and four-part humeral fractures with an inversion angle >20°.
The patient’s underlying condition also affects the outcome of treatment. For example, osteoporosis can affect fracture healing and lead to failure of the internal fixation, so such patients should undergo shoulder arthroplasty. In addition, damage to the rotator cuff musculature will affect the functional recovery of the patient’s shoulder after hemiarthroplasty.
Surgical techniques for hemiacetabular arthroplasty
The authors recommend a modified “beach chair” position: the head of the bed is raised to 45° and the arm is lowered to allow for extension of the incision. After identification of the cephalic vein, a deltopectoral approach is taken, separating the deltoid and subacromial regions and identifying the interbiceps groove. A Mason-Allen suture is performed to repair the rotator cuff musculature to help reposition the humeral tuberosity.
The fracture line in an intertrochanteric fracture is commonly located slightly posterior to the intertrochanteric sulcus. Next, the humeral head is excised, the humeral stem is exposed through medial and lateral Bennet retractors, and the medullary cavity is prepared by drilling a hole after successive dilation of the medullary cavity. At the same time, the surgeon must select a suitable humeral prosthesis based on the anatomic landmarks described above.
Then, two holes are drilled through the bone 1.5 cm away from the fracture. The first suture is passed outside through one of the holes to the proximal humerus, where the greater tuberosity can be fixed to the humeral prosthesis, and the other suture is used to fix the tuberosity to the humeral prosthesis in an anterior to posterior fashion. The authors recommend the use of a non-cemented prosthesis, but take into account the patient’s degree of osteoporosis and the length of the fracture line.
An attempt at fracture repositioning is also required before the implantation of the prosthesis is completed, which will clarify the proper size of the prosthesis and the stability of the shoulder joint.
After satisfactory fixation of the prosthesis is obtained, the surgeon needs to fix the humeral tuberosity to the prosthesis. First, a suture through the middle fracture of the greater tuberosity is wrapped around the prosthesis, a longitudinal suture through the drilled hole in the distal humeral stem is wrapped around the greater tuberosity, and two sutures through the top and tail of the greater tuberosity are wrapped through the lesser tuberosity. The greater tuberosity is then drawn in front of the prosthesis and secured 5 cm from the top of the humeral head, tied together with a suture through the middle suture of the greater tuberosity and a suture through the hole in the distal humeral stem, and tied together with a suture through the tip and tail of the greater tuberosity to help reset the greater and lesser tuberosities of the humerus. A 8-way suture is tied to the humeral tuberosity from the distal humeral stem to the proximal suture.
The stability and range of motion of the shoulder joint is assessed postoperatively, and the prosthesis and humeral tuberosity are repositioned by radiographs.
Postoperative complications of hemiarthroplasty, such as prosthesis loosening, rotator cuff injury, or non-union of the humeral tuberosity, can affect the clinical prognosis. Currently, there is an increasing preference for the use of reverse shoulder arthroplasty for proximal femoral fractures.
Indications for Reverse Shoulder Arthroplasty
Current indications for reverse shoulder arthroplasty include rotator cuff dysfunction and proximal humeral fractures with non-union of the greater tuberosity of the humerus.
In addition, the patient’s underlying conditions can affect postoperative healing of the humeral tuberosity, such as combined osteoporosis, comminuted fractures, and female patients. After completing the risk factor assessment, it is also important to understand the patient’s pre-injury shoulder joint mobility. If the patient had humeral glenoid arthritis prior to the injury, a reverse shoulder arthroplasty should be performed. Reverse shoulder arthroplasty is an option when an acute proximal humeral fracture occurs or when a hemiarthroplasty has failed.
Surgical technique of reverse shoulder arthroplasty
The authors believe that the key to a reverse shoulder arthroplasty is the reconstruction of the humeral tuberosity. The patient is placed in the Semi-Fowlers position with the arm freely lowered to allow for free movement during internal and hyperextension of the shoulder. A standard pectoral approach is used, and after adequate exposure of the operative field, the humeral tuberosity is marked at the junction of tendon and bone with a non-absorbable thick wire.
Nodal repair reconstruction in reverse shoulder arthroplasty; A, transverse and longitudinal sutures; B, humeral nodal reconstruction.
Next, the humeral head fracture mass is removed and the medullary cavity is manually expanded to prevent a medically induced fracture or enlargement of the fracture site. The glenosphere is exposed with a retractor, the glenosphere area is enlarged, a baseplate is placed, screws are driven for fixation, and a glenosphere is placed.
Then, 2 holes are drilled in the postero-lateral and 2 holes in the postero-medial biceps interosseous groove and a non-absorbable wire is passed through to fix the humeral tuberosity. The humeral prosthesis was inserted into the medullary cavity at a posterior tilt of 20-30° and the shoulder joint was repositioned according to the trial position of the prosthesis. After measuring the range of motion of the shoulder joint and deltoid tone, the trial mold is removed, the glenosphere is placed, and the humeral prosthesis is inserted.
The next step is the reconstruction of the humeral tuberosity. After wrapping a suture across the tuberosity transversely around the medial side of the humerus, it comes out at the muscle-tendon junction and is fixed through another humeral tuberosity. Then, a humeral socket prosthesis is inserted and the shoulder joint is successfully repositioned. Finally, the longitudinal suture that originally passed through the humeral stem is tied and secured after crossing the superior aspect of the humeral tuberosity, and the transverse suture is also tied and secured immediately afterwards. After completion of humeral tuberosity reconstruction, humeral tuberosity stability can be confirmed by abduction and rotation of the shoulder joint.
Postoperative rehabilitation exercises
A shoulder sling immobilizer with an abduction pad is used for at least 6 weeks postoperatively to promote healing of the humeral tuberosity. During this time, patients are encouraged to perform active functional exercises of the distal extremity, and moderate passive pendulum movements of up to 120° can help restore shoulder function. If the postoperative plain radiograph indicates healing of the humeral tuberosity and no imaging evidence of fracture displacement, the patient is encouraged to begin active functional exercises of the shoulder at 6 weeks postoperatively.
Efficacy of hemiarthroplasty versus RTSA
Professor Gallint et al. retrospectively studied the outcomes of patients with complex three- or four-part fractures of the proximal humerus treated with hemiarthroplasty or reverse shoulder arthroplasty, respectively. The results showed better recovery of shoulder motion in the RSTA group, with 91° and 97.5° of abduction and forward flexion, respectively, compared with 60° and 53.5° in the post-hemiarthroplasty group. In addition, the Costant score was 14 points higher in the RSTA group than in the hemiarthroplasty group (53 versus 39). The results suggest that patients in the RSTA group recovered better from surgical shoulder function.
It has also been shown that RSTA is more effective in patients older than 70 years of age for complex three- or four-part fractures of the proximal humerus due to the uncertainty of the healing of the humeral tuberosity in patients after both procedures.
In another study by Professor Gallint, the prognosis of patients after RSTA was shown to be better at long-term follow-up, but the surgeon must take into account the cost of the procedure and the life expectancy of the patient when choosing the procedure.
Indications for shoulder arthroplasty for three- or four-part fractures of the proximal humerus
In conclusion, the authors concluded that hemiarthroplasty is indicated for the treatment of complex three- or four-part fractures of the proximal humerus, especially in patients at high risk for humeral head necrosis or with co-morbidities such as osteoporosis. However, patient healing is closely related to the level of the surgeon and the underlying condition of the patient itself. Therefore, more and more surgeons are preferring to use reverse shoulder arthroplasty. This is because they believe that RSTA can counteract risk factors such as severe osteoporosis, non-healing humeral tuberosity and pathological rotator cuff injury.
Although studies have shown that RSTA patients recover well from postoperative shoulder function, the high rate of postoperative complications cannot be ignored. However, there is still a lack of evidence to guide a uniform indication for surgery. The choice of the correct surgical approach can only be made by the surgeon based on his or her extensive clinical experience.