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Nonunions following fracture fixation result in significant patient morbidity and financial burden. Traditional operative management around the elbow consists of removal of metalwork, debridement of the nonunion and re-fixation with compression, often with bone grafting. Recently, some authors in the lower limb literature have described a minimally invasive technique used for select nonunions where simply placing screws across the nonunion facilitates healing by reducing inter-fragmentary strain. To our knowledge, this has not been described around the elbow, where traditional more invasive techniques continue to be employed.
Aims
The aim of this study was to describe the application of strain reduction screws for management of select nonunions around the elbow.
Methods & Results
We describe 4 cases (two humeral shaft, one distal humerus and one proximal ulna) of established nonunion following previous internal fixation, where minimally invasive placement of strain reduction screws were used. In all cases, no existing metal work was removed, the nonunion site was not opened, and no bone grafting or biologic stimulation was used. Surgery was performed between 9 and 24 months after the original fixation. 2.7 mm or 3.5 standard cortical screws were placed across the nonunion without lagging. Three fractures went on to unite with no further intervention required. One fracture required revision fixation using traditional techniques. Failure of the technique in this case did not adversely affect the subsequent revision procedure and has allowed refinement of the indications.
Conclusion
Strain reduction screws are safe, simple and effective technique to treat select nonunions around the elbow. This technique has potential to be a paradigm shift in the management of these highly complex cases and is the first description in the upper limb to our knowledge.
Skeletal nonunions can cause substantial morbidity because of unplanned further surgical procedures, complications and impaired function. They also produce significant economic expense with humeral shaft nonunions estimated to cost in excess of £15,000 to manage.
Nonunions around the elbow still occur despite advances in surgical techniques and implants. The rate of nonunion following fixation of the humeral shaft, distal humerus and proximal ulna is reported to be 2–34%,
particularly for older patients or those with post traumatic arthritis and poor bone stock in addition to the nonunion. Revision distal humerus fixation with bone grafting and TER have complication rates of 11–42% and 18–75% respectively.
In the proximal ulna, revision ORIF with or without bone grafting is also the most often described treatment, though excision and arthroplasty have also been reported. Persistent nonunion after revision fixation is still reported to be between 7 and 10%
and arthroplasty in the setting of proximal ulna bone loss is particularly challenging.
Hence, regardless of which bone is affected, these techniques all represent a substantial surgical morbidity for patients with high complication rate and frequent occurrence of persisting symptomatic nonunion.
Nonunion occurs because of one or more of the following factors: Inappropriate mechanical environment resulting from inadequate interfragmentary compression, malalignment or poor fixation constructs. A poor biologic environment including excessively stripping bone of its soft tissue attachments and therefore its blood supply or the presence of infection.
The strain environment of the fracture is critical in determining how bone heals and surgeons should strive to optimise this strain environment in order to facilitate bone healing. These concepts were introduced and established by Perren,
In this model, primary importance is placed on the mechanical environment of the nonunion with the aim being to optimise stability and reduce strain through interfragmentary compression. This is applied in clinical practice using the techniques already described but it has been taken further by some authors
who have described the role of ‘strain reduction screws’ across a nonunion in patients. This involves placement of standard cortical screws across the nonunion site without removal of existing metalwork, lagging or grafting and is a quick technique that can be performed percutaneously depending on body region. The technique has almost exclusively been described in lower limb nonunions of the femur and tibia so far and the pre-requisites are an absence of infection, acceptable limb alignment and a uniplanar nonunion with some degree of stability. Such nonunions may also be described as ‘hypertrophic’ in more traditional thinking and is the most common scenario surgeons dealing with nonunion face following previous fixation.
have replicated these results with 88% union in the lower limb. Most importantly though, the surgical insult and morbidity to the patient is substantially lower than that of standard techniques.
Thus far, this technique has not been reported in nonunions around the elbow and consequently, traditional ‘maximally’ invasive techniques continue to be employed as the first line treatment of nonunion.
We describe a series of cases where strain reduction screws have been successfully used to treat a variety of nonunions around the elbow with the aim that our experience gives other surgeons the confidence to consider this low morbidity, simple technique in the treatment of their patients.
Case 1: - Distal Humerus NonUnion Following Corrective Osteotomy
A 26 year old right hand dominant man presented with ulnar nerve neuritis and a 20° cubitus varus of the left elbow following a childhood supracondylar fracture treated non operatively in plaster. He had also had one episode of elbow dislocation 8 months prior to referral and had an ongoing deep ‘popping sensation’ in the elbow (Fig. 1; A). He initially had ulnar nerve decompression and subcutaneous transposition and then subsequent corrective supracondylar osteotomy and plating because of ongoing symptoms. Following this, he developed a symptomatic nonunion at the osteotomy site. This was treated expectantly and with low intensity pulsed ultrasound (LIPUS) therapy, but failed to unite despite this and he was referred to our care at 18 months following the osteotomy (Fig. 1; B).
Fig. 1A - Pre-operative radiographs. B - Non Union at 18 months post osteotomy and LIPUS therapy. C - Radiographic Union 2 months after strain reduction screw fixation.
His workup for surgery revealed normal inflammatory markers, a quiescent wound and radiographic evidence of a well aligned limb, intact metalwork and a painful supracondylar nonunion. He underwent surgery 24 months after the original intervention. Examination under anaesthesia demonstrated a positive posterolateral rotatory drawer test confirming the presence of posterolateral rotatory instability (PLRI) caused by chronic attenuation of his lateral ulna collateral ligament (LUCL).
A limited para-tricipital approach was performed using the previous scar and centred on the nonunion site. The ulnar nerve was not re-exposed and a limited dissection was performed to only expose the plates at the level of the nonunion site. Microbiologic samples were taken from the nonunion without exposing it fully or elevating the triceps. Two 3.5 cortical screws were placed bicortically across the nonunion site without lagging or any further stimulation of the nonunion site. Postoperatively, the patient was placed in a sling for comfort but allowed to mobilise the limb actively as pain allowed immediately following the surgery. At 2 months follow up, radiographs demonstrated union (Fig. 1; C) and complete resolution of the patients pain.
Due to the presence of PLRI and an ongoing feeling of instability the patient underwent planned removal of the metal work and lateral ulna collateral ligament reconstruction using a gracilis allograft 5 months later. Following this procedure his instability symptoms were resolved and he was discharged from follow up with a pain free elbow and full range of motion.
Case 2: - Proximal Ulna Nonunion Following Multiple Procedures And Stress Fracture
A 65 year right hand dominant female initially presented to our institution with a closed, peri-prosthetic fracture of the left olecranon after a fall from standing height with no neurological deficit. The previous fixation had been for a proximal ulna shaft fracture and was performed at another institution 2 years prior (Fig. 2; A). Her co-morbidities included type 2 diabetes, osteoporosis, ischaemic heart disease and severe asthma with ongoing long term oral steroid therapy. She underwent removal of metalwork and tension suture fixation
(Fig. 2:B) with uneventful union of the olecranon. Unfortunately, 7 months later she developed an undisplaced stress fracture seen on the posterior surface of the proximal ulna around the screw holes of the original plate fixation and distal to the united peri-prosthetic fracture that had been treated with tension band sutures (Fig. 2; C). This was initially treated in plaster but did not heal and eventually resulted in a complete, displaced and painful nonunion (Fig. 2; D). Examination, revealed no significant motion at the nonunion site but marked pain on palpation. There was an apex posterior and varus deformity present and her skin was poor quality due to the long term steroid use and multiple previous operations. Despite continued non-operative management and maximal pain management the patient insisted on intervention due to the impact on her day to day life. Her situation posed a significant surgical challenge due to the deformity and co-morbidities and it therefore deemed most appropriate to perform strain reduction screw fixation rather than deformity correction, revision fixation ± grafting.
Fig. 2A - Periprosthetic fracture of proximal left ulna. B - Post operative radiographs following tension band suture fixation. C - C - Stress fracture noted distal to tension band fixation on posterior ulna cortex. D - Completed stress fracture of proximal ulna distal to previous fracture treated with tension band suture. Varus and apex posterior deformity has developed. E − Radiographic union 5 months post strain reduction screw fixation.
Surgery was performed at 13 months following development of the stress fracture under regional block anaesthesia. Fluoroscopy was used to localize the nonunion site and a very limited incision was made at this area. A 2.7 mm cortical screw was placed without lagging or disturbance of the nonunion site. Postoperatively, the patient was placed in a sling for comfort but allowed to mobilise the limb actively as pain allowed immediately following the surgery. At follow up the patient had complete resolution of her pain and there was full radiographic union demonstrated at 5 months following surgery. There were no complications and she was able to return to her desired level of function and independence (Fig. 2; E).
Case 3: - Humeral Shaft Fracture With Nonunion Around Intramedullary Nail Fixation.
62 year old right hand dominant active female presented with a closed segmental left humeral shaft fracture after a fall from a standing height with no neurological deficit (Fig. 3; A). This was managed with closed intramedullary nail fixation. At 1 year following surgery, whilst there had been radiographic union of the distal fracture, a nonunion of the proximal fracture was noted (Fig. 3:B).The patient had pain at rest and with activity localized to the nonunion site. There was no clinical or biochemical evidence of infection or metalwork failure hence she was treated with strain reduction screw fixation. This was performed with the patient supine and done percutaneously using 3.5 mm cortical screws bicortically via a small stab incision (Fig. 3C). Postoperatively, the patient was placed in a sling for comfort but allowed to mobilise the limb actively as pain allowed immediately following the surgery. At 7 months follow up there was complete resolution of her symptoms and radiographic evidence of bridging callus at the proximal fracture (Fig. 3D).
Case 4: - Humeral Shaft With NonUnion Around Plate Fixation
Fig. 3A - Segmental Left Humeral Shaft Fracture. B - Non union of proximal fracture segment at 1 year. C - Intra-operative imaging of strain reduction screw fixation. D - 7 months post op demonstrating bridging callus.
A 49 year old right hand dominant female sustained a closed humeral shaft fracture following a fall from a standing height (Fig. 4; A). At presentation, a radial nerve palsy was noted and she underwent open reduction internal fixation (ORIF) with 3.5 mm compression plating through an anterolateral approach the following day. At operation, the radial nerve was noted to be contused for a 2 cm length, tented over the fracture site but in continuity. The radial nerve palsy recovered in full at 3 months following surgery but unfortunately, she developed a painful nonunion with metal work failure noted (screws broken and plate loosening) at 7 months following surgery (Fig. 4; B). Upon investigation, no systemic or biochemical evidence of infection was found. There was a reluctance from both surgeon and patient to perform a large dissection around a recently recovered radial nerve palsy and hence at 1 year following initial ORIF, the patient underwent strain reduction screw fixation. The patient was positioned supine and a small anterolateral incision at the proximal part of the previous approach was used. Two 3.5 mm cortical screws were placed obliquely and bicrortically across the nonunion site using fluoroscopy to check positioning and without disturbance of the nonunion site (Fig. 4; C). Postoperatively, the patient was placed in a sling for comfort but allowed to mobilise the limb actively as pain allowed immediately following the surgery. At 6 months following this procedure, there was persistent evidence of nonunion and further failure of fixation (further screws broken and increased plate loosening) (Fig. 4; D). At this stage, the patient underwent removal of the failing metal work through an anterolateral approach, debridement of fracture site and revision dual compression plating with 3.5 mm and 2.7 mm plates for increased mechanical stability. Good bone apposition with no bone defect was found at this operation so no bone graft was required. This second procedure was successful in achieving clinical and radiographic union at 6 month follow up (Fig. 5).
Fig. 4A - Left Humerus Shaft Fracture. B - Non Union of Humeral Shaft Fracture 7 months after fixation with early evidence of failure of fixation. C - Intra-operative Imaging Demonstrating Strain Reduction Screw Fixation. D - Post Operative Radiographs at 3 months demonstrating persistent non-union and further failure of metalwork.
Fig. 5A/B - Lateral and AP left humerus demonstrating radiographic union after traditional revision open reduction internal fixation with no bone grafting.
In this case series we have described a simple, low morbidity technique that can be successfully used to treat select nonunions of the proximal ulna and humerus. To our knowledge, this is the first time the technique has been described in treating nonunions around the elbow.
have reported the successful use of this technique and frequently employed it in a completely percutaneous manner. Percutaneous placement of screws is more suitable for the tibia and femur where neurovascular structures can be safely negotiated. This is more difficult in the humerus in particular, which is why only one of our cases was performed completely percutaneously. In the other cases limited incisions were made in order to protect neurovascular structures but with little extra morbidity compared to a purely percutaneous approach. The principle of the technique remains unchanged, with virtually no disruption of the nonunion site in each case. In the case that ultimately required formal revision fixation of the humerus (Case 4), the placement of strain reduction screws did not compromise the later procedure, which is a benefit of the technique.
Case 4 was included in this series despite the technique not resulting in union. In this case, the original plate and screw fixation was already failing indicating a very unstable mechanical environment; this is not the best indication for strain reduction screws and in hindsight the technique may not have been appropriate. In the other cases, there was no radiographic evidence of interfragmentary motion at the nonunion such as failing fixation. In these cases, we believe that the nonunions had occurred because the interfragmentary strain was too high for healing but not so great that the fixation had been stressed to the point of failure and at this stage, placement of a strain reduction screw in this scenario sufficiently reduced the strain environment enough to achieve union.
No formal cost analysis was performed comparing this case series to traditional treatment strategies. There is likely to be a reduced cost compared to other techniques which require longer surgical times and more implants, particularly if allogenic grafts or arthroplasty are considered. The cost of repeat surgery if this technique fails and the time associated whilst awaiting union must be acknowledged, but overall, we feel this is balanced by the advantages of decreased patient morbidity and relative ease of this technique.
It is also acknowledged that this is a small case series in a heterogenous group of patients. The case numbers are small which reflects the fact that this technique is not applicable to every nonunion around the elbow. This reflects the heterogenous nature of nonunion and reconstructive surgery as a whole. We also accept that there are even less invasive techniques that might be employed such as LIPUS, which has many advocates. It would certainly be reasonable to try ultrasound-based therapies prior to surgical intervention. This was done in case 1 and was unsuccessful; this is both consistent with our institutions experience of LIPUS and the findings of a number of randomized trials.
Based on our experience, and that of others, the technique should be applied to specific nonunion situations as follows:
1.
The nonunion being treated should be uniplanar (a single non union fracture line must be present)
2.
It should be possible to pass screws around existing metal work
3.
Ideally screws should be passed perpendicular to the plane of the nonunion
4.
The nonunion should not be infected
5.
There should not be bone loss or a large gap at the nonunion site
6.
The mechanical environment should already be relatively stable
Defining what exactly is meant by ‘relatively stable’ is challenging, but it might be explained in clinical practice by a situation where there is no apparent motion between the fracture fragments. This in practice is often indicated by the presence of intact metalwork and maintenance of alignment after primary fixation.
Much of the existing literature on this technique is in relation to patients with existing fixation in situ, however, we have shown it also works in patients without metalwork in place (Case 2) where the indications outlined above were present.
3. Conclusions
This case series describe a new technique which can be applied selectively to nonunions around the elbow. The technique is based on an understanding and application of strain theory and bone healing, and while it does not completely replace traditional techniques, it has the potential to drastically reduce the morbidity of patients with such nonunions. As such it represents a potential paradigm shift in management but should be applied on an individualised basis by surgeons treating these patients frequently.
References
Kanakaris N.K.
Giannoudis P.V.
The health economics of the treatment of long-bone non-unions [published correction appears in Injury.
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