Abstract
The incidence of fracture non-union in conservatively treated proximal humerus fractures ranges from 1.1-10%, compared to 5.5% in the mid-humerus. When a humeral fracture is treated conservatively for 6-8 weeks and there is no sign of progressive fracture healing on x-ray, surgery should be offered. Recent series have shown that in more than 90% of cases of nonunion of proximal humerus fractures, successful healing is achieved with locking plates and autogenous bone grafting.
Shoulder arthroscopy can be used as a palliative treatment for patients with proximal humeral fractures resulting in humeral head necrosis or fragments of the humeral head that cannot be effectively fixed. In patients with non-healing humeral stem fractures, compression plates + autogenous bone grafting remain the gold standard of treatment, and recent studies support the use of locked compression plates with double plate fixation and parallel cortical bone support in patients with reduced bone mass.
Introduction
Humeral fractures account for approximately 5-8% of all types of fractures. Conservative treatment is usually recommended for the majority of humeral stem fractures (>95%) and proximal humeral fractures (89.1%). Conservative treatment of humeral fractures in some patients can result in nonunion or delayed healing of the humeral fracture, and because the causes of nonunion are similar between conservative and surgical treatment of the humerus, reoperative treatment can be quite challenging in these patients.
There are many reasons for nonunion of humeral fractures, including physiological (reduced blood supply, smoking, medical comorbidities) and mechanical (inadequate braking, fracture type, fracture displacement) aspects, and the impact of these factors on fracture healing should be fully considered when treating patients conservatively.
The goal of surgical treatment of patients with nonunion of humeral fractures is to provide stable mechanical support, allow early functional exercise and create a microenvironment conducive to fracture healing. There are many strategies for treating nonunion of the humerus, but incision + compression plate + autogenous bone graft remains the gold standard for the treatment of nonunion of the fracture. Other approaches such as intramedullary filling with autogenous fibular bone graft for non-healing proximal atrophic fractures and double plate treatment for patients with non-healing fractures with bone loss have also been reported in the literature and clinically applied.
Non-healing proximal humerus fracture
Proximal humerus fractures are a relatively common type of fracture in orthopedics and are usually low-energy, non-displaced or minimally displaced fracture types. For most patients, these fractures heal conservatively, but can often have a greater impact on patients who do not heal within 6 months of fracture surgery. in a study of 124 patients with conservatively treated proximal humerus fractures, Hanson et al. found that only 3% of patients required surgery for nonunion of the humerus at 1-year follow-up. Similarly, Court and McQueen et al. reported a fracture nonunion rate of approximately 1.1% for conservatively treated proximal humerus fractures.
The risk factors associated with nonunion of proximal humeral fractures have been well studied; Court et al. found that fracture nonunion occurred in approximately 8% of patients with comminuted metaphyseal fractures, compared with 10% of patients with 33-100% displacement of the surgical neck of the humerus. The type of fracture may also be associated with fracture nonunion. Two-part surgical neck fractures are the category of humeral fractures most associated with fracture nonunion.
All of these seemingly unrelated factors may be due to the same cause: the above factors lead to tearing of the medial soft tissue, which is important for bone healing. The rate of nonunion of fractures is 5.5 times higher in smokers than in nonsmokers. Other medical conditions such as diabetes, osteoporosis, and obesity may have an impact on fracture healing and require a detailed, thorough evaluation by an internist prior to surgical treatment of these patients.
Patient Assessment
Patients with non-healing proximal humerus fractures usually complain of pain, shoulder stiffness, and motor dysfunction. On examination, there is reduced forward shoulder elevation with or without disuse atrophy of the deltoid and periscapular muscles. In these patients, axillary nerve function needs to be evaluated and electromyography needs to be performed if axillary nerve injury is suspected. The fracture should be evaluated on radiographs in neutral shoulder position, anteroposterior internal and external rotation, thoracic outlet and axillary views.
In all patients with nonunion, the type of nonunion (augmentation or atrophy) must be determined first. On imaging X-rays, proliferative nonunion is usually characterized by osteonecrosis of the fracture end with surrounding crust growth, whereas atrophic nonunion is characterized by a reduction in bone mass at the fracture end without crust formation. In atrophic fractures, the local vascular and biological microenvironment required for fracture healing is impaired and fracture healing is inadequate.
In patients with proximal humeral fractures, attention is paid to the possibility of aseptic necrosis of the humeral head and pathological fractures during imaging evaluation, and bone quality needs to be assessed by X-rays. Contralateral shoulder X-rays are useful to improve the accuracy of the evaluation. If the fracture does not heal on X-rays alone, CT can be performed.
Timing of surgery
Non-union is usually diagnosed when the long bone fracture has not tended to heal for more than 6 to 9 months. In conservatively treated patients, the long bones usually begin to heal or form bridging scabs at about 13 weeks, and clinical intervention is required if there are signs of nonunion on radiographs at this time. Failure to heal is also diagnosed in conservatively treated patients who do not show signs of progressive fracture healing on two consecutive radiographs at 6 and 8 weeks.
At 3-6 months post-injury, surgical intervention is recommended if there is a suspicion of fracture non-union in combination with associated risk factors for fracture non-union, such as preoperative osteoporosis, significant fracture displacement, and soft tissue envelope tears. Surgical intervention at this point in time can be effective in preventing the development of glenohumeral instability following chronic proximal humeral fractures that do not heal.
Non-surgical treatment
In patients with symptomatic proximal humerus fractures that do not heal, non-operative treatment is only indicated in cases where severe medical complications are combined and surgical treatment is not tolerated; or where post-operative rehabilitation and functional exercises are not expected to be cooperative. In contrast, conservative treatment is an appropriate option for patients with non-healing humeral fractures with only mild pain or mild functional loss.
Surgical treatment
Osteosynthesis (osteotomy)
Indications for internal fixation with locking plates for proximal humeral fractures: good bone quality, a nailable humeral head, and no significant medial cortical comminution fracture or bone loss. Clinical assessment of the function and integrity of the greater tuberosity of the humerus by imaging radiographs is important in selecting an appropriate internal fixation protocol for proximal humeral fractures.
In patients with non-healing surgical neck fractures, strong fixation of the fracture can be achieved using more types of plates. For example, 3.5 mm or 4.5 mm proximal humeral plates, angled plates (blade plates) or 4.5 mm T-plates. Locking plates or angled plates with fixed angles can provide stable support for osteoporotic fractures.
Isolated large or small tuberosity fractures are less common than fractures of the surgical neck of the humerus. The need for surgery depends on the quality of the fracture fragment and rotator cuff function. If the large tuberosity fracture is large enough, it can be fixed with tension screw compression or a support plate + autogenous bone graft. In patients with a functioning rotator cuff and a more severe humeral tuberosity comminution, tension band fixation, or transcortical sutures, or suture anchoring techniques in the repair of rotator cuff injuries may be used.
These procedures can be accomplished through a deltoid pectoralis major approach or an interdeltoid approach. If the proximal humerus fracture does not heal as a small tuberosity portion, the deltoid pectoralis major approach is recommended. There are also cases reported in the literature where treatment of nonunion of the greater tuberosity fracture of the humerus was accomplished through shoulder arthroscopy.
In patients with nonhealing fractures, autogenous bone grafting of the broken end is recommended along with the application of internal fixation. The large amount of bone required for the implant can be obtained from the iliac site, but the surgeon needs to be careful to inform the patient preoperatively of the potential for pain at the donor site. Allograft bone grafting may be considered if the patient cannot accept the adverse consequences of the autologous bone acquisition site.
Recently, the Reamer-irrigator-aspirator (RIA) system has been used to obtain large amounts of autologous bone for the treatment of large cortical bone defects and non-union fractures. This method is effective in reducing the incidence of postoperative pain at the iliac donor site and in obtaining more pluripotent mesenchymal stem cells. In patients requiring strong mechanical support for bone grafting, the use of a fibular bone graft block with a vascularized tip may be considered for bone grafting.
Healy et al. reported 13 patients with nonunion of humeral fractures treated with internal fixation + bone grafting and 12 patients achieved fracture healing. The percentage of patients with good to excellent postoperative shoulder function was 80%, while only two patients had pain at the donor bone site.
Allende et al. reported successful treatment of seven cases of proximal humeral nonunion with a 90-degree blade plate, with a mean follow-up of 22 months and a mean postoperative healing time of 5.9 months, and shoulder DASH and Constant scores of 25 and 72.7, respectively.
Fixed Angle Locking Plate + Autogenous Fibular Bone Graft
Badman et al. 2006 was the first to use a fixed-angle locking plate combined with an autogenous fibular bone graft to treat a non-healing proximal humeral fracture. The fibular bone graft has many advantages: it provides high strength support for the proximal humeral fracture and avoids possible complications at the iliac bone donor site. This method can also be used in patients with acute proximal humeral fractures that lack support in the presence of medial cortical comminution. (Figure 1)
Intraoperative radiograph of an acute surgical neck fracture of the humerus in a patient with severe osteoporosis (A), corresponding to an anterior-posterior radiograph (B). Bone graft using a proximal humeral locking plate and an intramedullary fibular bone block. In B, a locking screw is placed through the plate hole to fix the fibular bone graft in an intermediate position, and a locking screw is placed over the plate locking hole to fix the fractured end. Intraoperative anteroposterior radiographs (C) and intraoperative axillary radiographs (D) show multiple locking screws penetrating the bone graft, which is medial to the medullary cavity and provides additional support for the medial bone.
Intramedullary nailing
Previously, in patients with proximal humeral fractures, the results of treatment with intramedullary nailing were unsatisfactory, mainly because the early design of the intramedullary nail in the humerus was prone to postoperative impingement of the shoulder crest, thus requiring a second surgery to remove the internal fixation. Despite this, most patients were able to achieve fracture healing and better shoulder function.
Recently, Yamane et al. reported 13 patients with nonhealing proximal humeral fractures treated with a locking intramedullary nail with satisfactory results, although two patients still required removal of the internal fixation due to proximal lock withdrawal.
Nonrestrictive and Reverse Shoulder Arthroplasty
The need for unrestricted shoulder arthroplasty depends on several factors: the degree of osteoporosis at the fracture end of the proximal humerus, the survival of the humeral head, and the functional integrity of the greater tuberosity and rotator cuff. Total shoulder arthroplasty may be considered if the patient also has osteoarthritis of the glenohumeral joint with intact rotator cuff function.
Boileau et al. studied the factors affecting the success rate of shoulder arthroplasty and found that humeral tuberosity integrity and anatomic position were important in influencing shoulder function. They therefore recommended a recommended reverse shoulder arthroplasty for patients in whom a greater trochanteric joint cannot be avoided, such as a Neer type 4 fracture.
Although studies have demonstrated that total shoulder arthroplasty in patients with nonunion of the proximal humerus can be effective in reducing patient pain, there are still many uncertainties regarding the functional recovery of the shoulder joint after surgery. The pain was significantly improved. However, none of the patients were able to return to their pre-injury level of activity.
Antuna et al. reported the clinical results of 25 shoulder replacement patients (21 hemi- and 4 total shoulder) who had not fully recovered shoulder function from pre-injury levels, although pain and shoulder function were significantly improved. The healing rate of humeral greater tuberosity fractures was only 52% (35 patients). Restoration of active shoulder elevation was associated with anatomic or near-anatomic healing of the greater tuberosity of the humerus.
Reverse shoulder arthroplasty is a better option for patients with humeral head collapse, or clinical rotator cuff dysfunction, or imaging signs of rotator cuff atrophy (Guotallier grade 2 or greater), or healed or resorbed acromioclavicular tuberosity combined with nonunion or delayed healing of the proximal fracture (Figure 2). Fourteen patients were satisfied or very satisfied with their postoperative shoulder function.
Figure 2: 81-year-old female with right lipped hand. The preoperative anteroposterior radiograph (A) and axillary radiograph (B) indicated a nonunion of the right proximal humerus fracture, severe osteoporosis, and bone resorption at the greater tuberosity of the humerus. Preoperatively, the patient had 40 degrees of shoulder joint mobility with forward elevation. After reverse shoulder arthroplasty, postoperative anteroposterior radiograph (C) and axillary radiograph (D). At 4 months after surgery, the patient’s forward lifting motion reached 160 degrees.
Non-healing humeral stem fracture
In the majority of patients with humeral stem fractures, successful fracture healing was achieved with functional brace fixation. Angular deformities of 20 degrees or less on both frontal and lateral views have limited impact on postoperative function of the affected limb. A recent systematic evaluation study by Papasoulis et al. showed that the overall incidence of fracture nonunion was approximately 5.5% in patients treated nonoperatively, whereas the literature over the past several decades has reported findings of fracture nonunion in conservative treatment of humeral stem fractures with functional braces in more than 50 cases in the range of 10-23%, which is consistent with the earlier literature reporting results of conservative treatment of humeral stem fractures. This is different from the results of conservative treatment of humeral stem fractures reported in the earlier literature.
A study by Hwaly et al. found that transverse fractures were the most likely to fail to heal, followed by short oblique fractures. A similar conclusion was reached in another study.
In a study by Ring et al, they found that spiral or oblique fractures were the least likely to heal (84.4%) in patients treated conservatively with a functional brace for a 10-year period for humeral stem fractures, while transverse fractures had a non-healing rate of only 12.5%. The rate of fracture non-union was higher with conservative treatment in OTA type A fractures than in type B or C fractures.
The location of the fracture also has an effect on fracture healing. This may be due to the fact that the proximal fracture is pulled by the deltoid muscle, which causes more micromovement of the fracture end; the long head of the biceps tendon sliding into the fracture end may also cause the fracture to not heal; and the fact that brace braking is more difficult in proximal humerus fractures.
Patient Assessment
Patients with nonunion of the humeral stem fracture usually present with the inability to use the affected limb repeatedly to perform the same repetitive motion. High-energy injuries and co-morbid medical conditions may have an impact on fracture healing. Selection of appropriate brace size and skin irritation-free materials may improve patient tolerance to brace therapy. The assessment of the fracture should be accompanied by an assessment of the patient’s neurological condition to exclude possible combined neurological injury. Excessive motion at the fracture site is a sign of nonunion, but the patient may not cooperate with this examination due to edema or pain at the fracture site.
On imaging X-rays, fracture nonunion may appear as angulation due to lack of crustal growth or hyperplastic crustal growth due to lack of stability of the fracture. CT is indicated when fracture healing cannot be determined by X-rays alone.
Other tests associated with fracture non-union include CBC, metabolic markers, etc. For example, if the patient has an open fracture preoperatively, inflammatory markers should be performed to exclude infected fracture failure at the fracture site; if the patient is in poor general condition, serum total protein and serum albumin should be performed; other laboratory tests, such as vitD, can be helpful in screening for the cause of fracture failure.
Timing of surgery
Most scholars suggest that the absence of imaging-visible bone crust growth at the fracture site 4 months after surgery is considered delayed bone healing, and the absence of bone crust growth at the fracture site 6 months after surgery is considered bone nonunion. The timing of surgical intervention for conservative treatment of nonunion of humeral stem fractures is still controversial; Toivanen et al. recommend surgical intervention after 6 weeks of brace fixation without obvious signs of fracture healing.
Other authors, such as Rutger, Ekholm et al. managed nonunion after 28 weeks and 36 weeks after conservative treatment, respectively. A systematic evaluation by Papasoulis et al. found that the mean time to healing of humeral stem fractures was 10.7 weeks, suggesting that intervention at 10-12 weeks should be more appropriate for patients with nonhealing humeral fractures. The possibility of nonunion should be highly suspected in all patients who do not show significant fracture healing progression on serial radiographs at 6-8 weeks postoperatively.
Non-operative treatment
Non-operative treatment does not guarantee healing of humeral stem fractures and is indicated only in cases where there are severe medical comorbidities that preclude surgical management, where the patient is not clinically symptomatic, and where functional requirements are low. Bone stimulation for growth is another approach, including low electrical pulse stimulation, acoustic stimulation, etc. These methods are not effective if the patient has a synovial pseudarthrosis, a fracture gap greater than 5 mm, or a low blood supply to the fracture end. The effectiveness of bone stimulation methods in the clinical application of non-healing humeral fractures is still unclear.
Surgical treatment
Internal fixation with compression plate incision and bone graft
Internal fixation with a 4.5 mm wide compression plate and bone grafting at the fracture site is the gold standard for the treatment of non-union of humeral stem fractures. Different approaches can be chosen for different fracture sites. Intraoperatively, care should be taken to expose the radial nerve for protection. If the nerve is within the fibrous scar tissue, nerve release can be performed as an adjunct.
Surgical fracture repositioning requires complete correction of the angular deformity, good joint axis alignment, and maximum cortical contact to ensure strong internal fixation. Non-healing fractures require careful debridement and irrigation and partial removal of the bone cortex to stimulate fracture healing. Depending on the fracture site, different surgical approaches are chosen.
Fracture fixation with 4.5 mm thick plates should be performed with at least 6 proximal and 8 distal cortices, respectively. To ensure balance after internal fixation, it is recommended to extend the plate at least 2-3 times the diameter of the humerus on both sides of the fracture. A minimum of 8 cortical fixations on each side of the fracture are required for fixation with a 3.5 mm thick plate (Figure 3). Depending on the fracture, the fracture may be precompressed with plates or screws, and Ring et al. reported healing in 32 patients with nonunion of the humeral stem fracture treated with incisional internal fixation.
Figure 3: 19-year-old female, right handed, with acute left-sided comminuted humeral trunk fracture, treated conservatively with anteroposterior radiographs (A).B. After 12 weeks of conservative treatment with a brace, no obvious signs of fracture healing were seen on anteroposterior radiographs. The patient has persistent pain and motion at the fracture site.C, X-rays after incision and internal fixation using a 4.5 mm steel plate, bridging both ends of the comminuted fracture, and bone grafting +DBM at the site of the partially comminuted fracture.D, anteroposterior and posterior X-rays 6 months after surgery suggesting fracture healing.
The application of osteophytes produced after marrow expansion, or autologous iliac bone at the fracture break can be effective in promoting fracture healing. In patients with augmented fracture healing, the bone crust at the broken end can be used as a bone graft to fill the fracture. Successful treatment of non-healing fractures with demineralized bone matrix (DBM) with or without BMP has been reported in clinical practice.
Hierholzer et al. reported that patients with aseptic bone delay or bone nonunion were treated with DBM or autologous iliac bone, respectively, with no significant difference in postoperative healing between the two groups, but 44% of patients with autologous iliac bone grafting had donor site pain.
Marit et al. reported that all 51 patients with nonunion of the humeral stem fracture showed healing after 1 year of compression plate fixation, and Livani et al. reported the same results. Therefore, it is recommended that plate fixation + autogenous bone grafting should be the treatment of nonunion in patients with nonunion if the patient can tolerate pain at the donor bone site.
Dual Plating
There are two studies that support orthogonal double plate fixation in patients with fractures that do not heal due to micromovement of the earlier internally fixed fracture. In patients with a short fracture on one side and poor bone quality, a new plate can be added to the original plate for orthogonal fixation.Rubel et al. found no significant difference in clinical outcomes between patients with single or double plates for nonunion of humeral fractures.Prasrn et al. reported that all elderly patients with osteoporosis who were fixed with double plates achieved fracture healing at 15.2 weeks postoperatively.
Autologous cortical bone block implant
The combination of a compression plate and a cortical bone graft can be used in patients with severe osteoporosis. In this case, the autogenous cortical bone block is placed on the opposite side of the plate or in the medullary cavity, and the plate screws are passed through the bone block from outside to inside, sandwiching the humerus in between to provide additional fracture fixation strength. Two recent studies suggest that the above treatments are significantly effective in treating non-healing atrophic fractures of the humeral stem.
Biologic Factors to Assist Fracture Healing
BMPs have been used clinically to assist in fracture healing. However, most of them have been used in tibial fractures, but not in the humerus. A recent systematic evaluation concluded that there is a lack of theoretical support for the clinical efficacy of BMP in the healing of extremity fractures. Therefore, no recommendation can be made for the use of BMP in nonunion of humeral fractures at this time.
SUMMARY
Nonunion of proximal humerus and humeral stem fractures was previously thought to be rare; however, a growing body of clinical literature suggests that the incidence of nonunion of humeral fractures may be higher than earlier clinical expectations. Functional brace therapy remains the first-line option for patients with nonunion of the humeral stem or proximal humerus fractures with a good fracture shaft that can be treated with braking.
There is still more controversy regarding the time point for diagnosis of nonunion of humeral fractures. Fracture nonunion can be effectively treated by surgical procedures such as incisional internal fixation combined with fracture break end grafting. The integrity and location of the greater tuberosity of the humerus and its function play an extremely important role in the choice of treatment options for patients with nonunion of the proximal humerus fracture.