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Treatment of Proximal Humeral Nonunions With a Locked Plate and an Intramedullary Strut Autograft

Smith, Geoffrey C. S. MBCHB, MRCS (ED), FRACS (ORTH); Cass, Ben MBBS, FRACS (ORTH), FA Orth A; Young, Allan MBBS, MSPMED, PhD, FRACS (ORTH)

doi: 10.1097/BTO.0b013e31827b9500
Tips and Pearls

Proximal humeral fractures are common and account for 5% of all fractures. As a result of the poor results of conventional plate fixation, a multitude of other operative techniques have been described for the treatment of displaced fractures. The use of locking plates has distinct mechanical advantages over other modes of fixation but does not always adequately hold the head fracture that relies on a medial buttress to prevent its collapse into varus. Nonunions of proximal humeral fractures are not uncommon and represent a significant challenge to the treating surgeon. We describe a technique to treat a proximal humeral nonunion that combines the use of a locked plate with an iliac crest corticocancellous bone peg to augment the mechanical strength of the calcar region and autogenous cancellous bone graft in an attempt to enhance union rates.

Avon Orthopaedic Centre, Bristol, UK

A.A.Y. has received honoraria from Rotation Medical and Tornier. The remaining authors declare that they have nothing to disclose.

Address correspondence and reprint requests to Allan Young, MBBS, MSPMED, PhD, FRACS (ORTH), Sydney Shoulder Specialists, Suite 201, Level 2156 Pacific Highway St Leonards, NSW 2065. E-mail: allanyoung@sydneyshoulder.com.au.

Proximal humeral fractures are common and account for 5% of all fractures.1 Eighty percent of fractures are nondisplaced or minimally displaced and these are generally treated nonoperatively.2 The decision to operate is generally based on patient factors and fracture configuration. A multitude of operative techniques have been described.2 Many of these techniques were developed to address the poor results of conventional plate fixation particularly in the elderly osteoporotic population.3 Failures of fixation typically result in a varus deformity of the head fragment and redisplacement of any tuberosity fragments as a result of their muscle attachments. The varus deformity of the head fragment generally occurs as a result of fracture configurations in which there is significant comminution of the medial calcar. Various methods have been described to enhance medial stability including dual plating4 and intramedullary plating.5

More recently, the development of locking plates that form a fixed-angle device theoretically diminish the risk of primary or secondary loss of reduction.6 The proximal humeral internal locked system plate (PHILOS; Synthes, Stratec Medical Ltd, Mezzovico, Switzerland) is a widely used such device. Despite their theoretical advantages, the results of locked plates have been variable.7–9

Emphasis has therefore been placed on techniques to maximize the mechanical strength of the locked-plate construct such as the inferomedial or calcar screw, medialization of the shaft, and impaction into the head fragment10 and ensuring that the fixed-direction screws pick up those parts of the humeral head with the best mechanical qualities.11 Other authors have suggested the use of an intramedullary fibular strut allograft in combination with a locked plate.12

The exact incidence of nonunion of proximal humeral fractures is unknown13 but may be as high as 23% in the elderly14 and is most common in surgical neck fractures.15

Nonunions or delayed unions can occur in fractures treated both operatively16 and nonoperatively.15,17 Both hypertrophic and atrophic nonunions have been described.13,18 Several factors have been linked to the development of a surgical neck nonunion including coexisiting medical comorbidities, age and osteoporosis, soft tissue interposition, inadequate closed treatment, inadequate internal fixation, and overly aggressive rehabilitation.13

Nonunions nearly always require surgical intervention as the patient typically have a painful, flail functionless arm.13

Successful fixation of a surgical neck nonunion is technically more demanding than fixation of an acute proximal humeral fracture as the already small osteoporotic proximal fragment has been further weakened by the rapid loss of bone associated with disuse.19 This is a feature of fractures that have been treated nonoperatively and operatively Figures 1 and 2.

Many of the same techniques used to address acute fractures have been described for nonunions. Both some form of internal fixation with or without bone graft,20–23 conventional arthroplasty,24 or reverse geometry arthroplasty have been described.25 Scheck21 used corticocancellous iliac crest cancellous graft in combination with Rush pins. Nayak et al17 reported on a treatment with either open reduction, internal fixation with tension band wiring and Rush rods or hemiarthroplasty. Ring et al20 and Sonnabend22 have published their results on the use of blade plates. Walch et al26 first proposed the use of an intamedullary bone peg to treat proximal humeral nonunions. Corticocancellous graft was harvested from the iliac crest, anterior tibia, or fibula to supplement fixation with either a T-plate or a blade plate. Peripheral cancellous bone graft was also packed around the fracture site. Galatz et al18 has reported on the use of autogenous cancellous bone graft and either a blade plate or a T-plate. The use of a locked plate with intramedullary fibular strut allograft27 and autogenous iliac crest cancellous graft28 has more recently been described. We describe the use of a locked proximal humeral plate in combination with an autogenous iliac crest corticocancellous bone peg. In general, the results of surgery for proximal humeral nonunions are not as satisfactory as those for fixation of acute fractures.29

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TECHNIQUE

We define nonunion as the absence of union 6 months after the fracture occurred. This diagnosis is primarily made on the basis of serial plain radiographs. We routinely perform a computed tomography (CT) scan as part of our preoperative planning. The CT scan is used to assess the size and location of the bone defect in the humeral head and whether there is sufficient remaining bone to obtain screw fixation in the proximal fragment (Fig. 3). The CT scan also allows assessment of the tuberosity fragments in the setting of 3 or 4 part fractures. A bone scan is not routinely requested unless there is any question of avascular necrosis of the proximal fragment on the plain radiograph. Magnetic resonance imaging is occasionally used to assess the rotator cuff integrity and to grade the degree of fatty atrophy of their muscle bellies. Clinically, we pay particular attention to the neurological status of the limb especially if there has been prior surgical intervention. Range of motion is also examined. Generally, there is significant loss of passive motion of the shoulder, although it can be difficult to assess this in the setting of a painful nonunion.

Surgery is offered if the patient is significantly symptomatic so long as medical comorbidities do not preclude general anesthesia. We aim to preserve the humeral head in physiologically young patients if the head fragment is vascularized and is sufficiently large to gain adequate fixation and the tuberosities are either not involved or are amenable to fixation. If these criteria are not met, then we prefer to perform either a hemiarthroplasty or a reverse geometry shoulder arthroplasty.

The procedure is usually performed under general anesthesia with an interscalene block. The patient is placed in a semi-beachchair position paying attention to be able to perform intraoperative fluoroscopy during the procedure. The arm is free draped and the iliac crest is prepped and draped. A deltopectoral approach is performed. The subdeltoid and subacromial spaces are released of adhesions. The rotator interval is opened and the long head of biceps tenotomized at the superior pole of the glenoid in preparation for later soft tissue tenodesis to the tendon of pectoralis major. The fracture site is identified and fibrous tissue and callus is carefully taken down. A curette is used to remove soft tissue from within the humeral head defect and freshen the margins of the cavity. The tuberosities are mobilized if required and tagged with stay sutures. The humeral head fragment is mobilized gently and reduced. This is either done with pressure from below with an elevator or by using a K-wire as a joystick. If the tuberosities are intact, the stay sutures can be used to assist with reduction. Care is taken to avoid causing any unnecessary further disruption of the medial calcar region. This region can usually be visualized from within the fracture due to extensive missing bone within the humeral head. Intraoperative fluoroscopy is used to confirm satisfactory reduction. A final assessment is made regarding the likely viability of the head fragment and the ability to obtain secure fixation. If the decision is made to continue with fixation, then bone graft is harvested at this stage. An oblique incision is made 2 cm below and parallel to the anterior iliac crest paying attention to avoid the lateral cutaneous nerve of the thigh. The crest is exposed subperiosteally on its superior surface and over its outer table for 2 cm and to define the location of the inner table. The graft can be harvested either with osteotomes or an oscillating saw. The graft is generally 6 cm long and consists of 2 cm of lateral cortex and the entire thickness of the inner cancellous bone. This leaves only the cortex of the inner table in situ. This yields a corticocancellous bone peg of approximately 6×2×1 cm. Occasionally, in patients with very thin iliac crests, we have harvested a tricortical graft of similar dimensions but including the inner table. Further cancellous bone is harvested from the iliac crest through the bony defect. Particular care is taken to close the periosteum over the donor site and the deep fascia to prevent hematoma formation.

The graft is now shaped with a rongeur according to the intramedullary diameter of the proximal humerus and the bony defect in the humeral head. The prepared graft is inserted into the medullary canal of the humeral shaft, and the humeral head is trial reduced on to the graft. Repeated modifications of the graft are often necessary until the graft fits within the humeral head defect enabling satisfactory reduction. Rotation is assessed clinically using the biceps groove as a guide. If the temporary reduction is not stable, then it may be held with provisional K-wires at this stage. The construct is now stabilized with a PHILOS locking proximal humerus plate placed lateral to the bicipital groove.

The plate is fixed to the shaft either with a K-wire or with a nonlocked shaft screw through the slotted sliding hole. The height of the plate is now checked clinically and radiologically to avoid subacromial impingement and also to ensure that a locked inferomedial calcar screw can be placed. The locking screws into the head fragment are now placed followed by nonlocking cortical screws into the remaining shaft holes.

The most superior shaft nonlocking screw usually engages and stabilizes the bone graft. However, even without screw fixation, the graft is usually quite stable after impaction. No specific attempt is made to engage the graft with the proximal locking screws; however a number of these can be felt to engage the graft during drilling (Fig. 4). We perform a woodpecker drilling technique to avoid joint perforation, whereby the drill bit is advanced only for a short distance, then pulled back before advancing again. This is repeated until subchondral bone contact can be felt. The presence of the bone graft can create occasional uncertainty, and thus, intraoperative fluoroscopy is useful to assess whether the drill has reached subchondral bone.

Cancellous bone chips are now placed and impacted around the fracture site and in any residual metaphyseal void. We also prefer to use an injectable synthetic bone graft substitute (Tricalcium phosphate and calcium sulfate; geneX; Biocomposites, Keele, UK) to fill remaining voids. Finally, multiple nonabsorbable sutures are placed (anteriorly, superiorly, posterosuperiorly, and posteriorly) through the rotator cuff tendon in horizontal mattress manner and secured to the suture holes in the plate. The reduction is now checked fluoroscopically one final time and screening performed to confirm that there are no screws penetrating the joint. The wound is closed in layers and the patient placed into a shoulder immobilizer with a small abduction pillow.

Postoperatively, the patient is kept in the sling for 6 weeks allowing removal for pendular exercises and axillary hygiene purposes only. Elbow wrist and hand movements are encouraged. Radiographs are taken at 2 and 6 weeks postoperatively, and if appearances are satisfactory, passive-assisted and active-assisted range of motion exercises are introduced. Active strengthening exercises are introduced at 12 weeks.

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DISCUSSION

There are only a small number of reported series of treatment of proximal humeral fracture nonunions. Most of these studies report results using conventional implants. For the most part, these implants have been superseded by newer designs such as anatomic-specific precontoured locking plates, which provide superior angular stability. Although the use of locked plates is widespread for proximal humeral fractures, their mixed results has led to the development of techniques to restore or augment the calcar region to prevent varus collapse. The technique described above incorporates the use of a locked plate in addition to an iliac crest corticocancellous bone peg to augment the mechanical strength of the calcar region and autogenous cancellous bone graft in an attempt to enhance union rates. We have found this technique to be successful in the treatment of nonunions resulting from both nonoperative and operative treatment of proximal humeral fractures (Fig. 5).

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Keywords:

proximal humerus; fracture; nonunion; surgery; locking plate; bone graft

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