WO2021038178A1

WO2021038178A1 - Bone plate

Info

Publication number: WO2021038178A1
Application number: PCT/GB2019/052429
Authority: WO
Inventors: Graham TYTHERLEIGH-STRONG
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-08-30
Filing date: 2019-08-30
Publication date: 2021-03-04
Anticipated expiration: 2022-02-28

Abstract

A bone plate (100) for securing a bone discontinuity, such as a fracture. The bone plate comprises a first region with a first securing portion (101), a second region with a second securing portion (102) and an elongate portion (103) between the first and second securing portions. In particular, the plate is twisted about its longitudinal axis such that the first and second securing portions (101) and (102) lie in different planes about the axis. Hence, when in use, the first securing region (101) is secured to a first portion of a bone (201), the second securing region (102) is secured to a second portion of a bone (202), the first and second portion of the bone being located either side of a bone discontinuity, wherein the elongate portion (103) spans the bone discontinuity.

Description

Bone Plate

FIELD OF THE INVENTION

The present invention relates to bone plates for securing bone discontinuities, in particular the present invention relates to twisted bone plates that allow for fixation of bone discontinuities.

BACKGROUND OF THE INVENTION

Fractures of the medial end of the clavicle were previously thought to be rare and have traditionally been treated non-operatively. However, whilst studies examining X-rays suggested medical end clavicular fractures to have an incidence of around 2 to 3% of all clavicle fractures (Robinson et al, Postachinni et al and Nordqvist et al), more recent evidence examining CT scans suggests that the occurrence of medial end clavicle fractures is much higher than previously thought (almost 10% in Throckmorton et al). It can be recognised that interpretation of a single radiographic view can be difficult, potentially leading to an underappreciation of medial third fractures. In addition, the non union rate for medial clavicular fractures has been reported as 8.3%, and for those fractures that do heal, problems with function and on-going pain occur in more than 50% of cases (Nowak et al; Robinson et al; Throckmorton et al).

Traditionally, non-operative treatment of medial clavicular fractures has been preferred, with a relatively high threshold before considering surgical fixation. This has been partly due to concerns with the close proximity of the posterior mediastinal structures and the technical difficulties of adequately stabilizing and fixing the relatively small medial fragment. However, the non-union rate was found to be 6.3% for nondisplaced medial third fractures and 14.3% for displaced fractures at 24 weeks after injury (Robinson et al 2004). Early anatomic reduction and fixation has been shown to reduce the time to functional recovery, with excellent outcomes and few complications.

A number of fixation methods, including various types of sutures, wires, screws, and plate configurations, have been described to treat medial end clavicular fractures (Bartonicek et al; Fransen et al; Gille et al; Kim et al; Oe et al; Sidhu et al; Stark et al). These have generally been as case reports or very small cases series with varying levels of success. Kirschner wires have been used alone, but these tend to be insufficient and may migrate (Bartonicek et al; Fransen et al). A hook plate has been used, with the hook in the sternum itself inducing a temporary arthrodesis; this also requires removal (Gille et al). Tension band sutures have been used, offering limited stability. They are less suitable for larger fragments, although they may be used in combination with a T plate, which may also be used alone (Kim et al). Even a staged procedure of medial clavicular fixation and middle clavicular offloading osteotomy with delayed osteotomy fixation has been attempted (Al-Yassari et al).

The use of locking plates has been reported with some success (Low et al; Sidhu et al, Tokiyoshi et al; Wang et al). The most recent and largest series fixed 19 of 20 displaced adult medial clavicular fractures by using a reversed lateral clavicle plate, contoured to the anatomy of the superior surface of the clavicle and the medial end fixed with unicortical screws (Sidhu et al). None of the patients sustained intraoperative damage to any of the surrounding vital soft tissue structures, and all of the fractures healed. However, there are concerns with how well the plate actually fits, plate positioning, and access for accurate screw insertion. Fixing the plate onto the superior surface of the medial end of the clavicle may compromise or damage the clavicular insertion of sternocleidomastoid (SCM) muscle and, due to the close proximity of the patient's head and neck, compromise and limit the number of precisely positioned screws; and of the 25 patients in their series, including 6 patients who had an osseous suture fixation, 17 reported symptoms of plate or wound irritation, and 3 patients felt this to be sufficiently severe to undergo elective removal of the hardware. In addition, a CT anatomy study looking at 418 clavicles in 209 patients found that the average sternal curvature of the clavicle in the axial plane was 34°compared with an average acromial curvature of 46°.8 The “built-in” curvature for typical lateral clavicle plates is between 44° and 46° (see Figure 2).

In light of this, it is therefore an aim of the invention to provide an improved bone plate for fixing such fractures.

SUMMARY OF THE INVENTION

To avoid potential damage to the SCM muscle, better contour the plate, and aid accurate screw insertion whilst minimising any potential damage to the surrounding neurovascular structures, in one embodiment, we have used a lateral clavicle locking plate that is twisted through 90°. The plate described herein allows for the medial end of the plate to be fixed to the anterior surface of the clavicle with multiple small unicortical locking screws and the lateral end of the plate to be twisted and fixed to the superior surface of the clavicle.

In one aspect of the invention there is provided a bone plate for securing a bone discontinuity, comprising a first region with a first securing portion; a second region with a second securing portion; and an elongate portion between the first and second securing portions; wherein the plate is twisted about its longitudinal axis such that the first and second securing portions lie in different planes about the axis.

In one embodiment, the plate is twisted about its longitudinal axis at an angle such that the first securing portion lies in a plane that is perpendicular to the second securing portion. In a preferred embodiment, the plate is twisted about its longitudinal axis through 90°. This allows for the plate to be secured more easily, for example in the case of securing a bone discontinuity in the clavicle, as the plate can be fixed onto the anterior medial end of the clavicle and the superior lateral end of the clavicle so as the head and neck structures do not obscure access, and damage to the SCM muscle is avoided.

In another embodiment, a surface of the plate that, in use, contacts a bone, is contoured to fit the curvature of the bone. This allows for the plate to be more closely fitted to the bone, as there is no angular mismatch and will consequently allow better healing of the bone discontinuity.

In a further embodiment, the bone plate is made of made of biocompatible material, high- grade titanium, titanium alloy or stainless steel. This allows the plate to be left inside the body, without need for an operation to remove the plate once the bone discontinuity is healed.

In another embodiment, the first and second securing portions each comprise at least one hole for receiving a screw. This allows for fixation of the bone plate to the bone with screws providing a secure fixture with the bone. In a preferred embodiment, the elongate portion also comprises at least one hole for a screw for securing the elongate portion to a bone. This will allow for further securing of the plate to the bone, to prevent the plate migrating. Said holes may be of varying diameter sizes to accommodate screws of varying diameter sizes. Screws may be locking unicortical screws (i.e. passes through only the near bone cortex) or locking/non-locking bicortical screws (i.e. passes through both the near and far bone cortices). Bicortical screws generally allow for strong fixation to bone than unicortical screws, however the drilling of bicortical screws comes with an increased risk of damage to structures proximal to the posterior side of the bone.

In preferred embodiment, the first or the second securing portion is broadened or flared. This gives an increased surface area for fixation to the bone, for example in the case of a medial end clavicle fracture, where there may only be a relatively small portion of the bone to secure the first or second securing portion to. This larger surface area allows for a greater number of holes for receiving screws, meaning that multiple small unicortical locking screws can be used to provide sufficiently strong fixation to the bone, rather than fewer larger bicortical screws which may cause damage to the posterior cortex and neurovascular structures in proximity to the posterior of the medial end of the bone. In one embodiment, the width of the plate tapers along at least a portion of the elongate portion from the broadened or flared first or second securing region towards the other of the second or first securing region. In an alternative embodiment, the width of the plate steps down at the interface between the broadened or flared first or second securing region and the elongate portion.

In one embodiment, when the plate is in use, the bone discontinuity is located at the end portion of a bone. In a particular embodiment, the bone discontinuity is a medial end clavicular fracture.

In a further embodiment, when the plate is in use, the first securing region is secured to a first portion of a bone, the second securing region is secured to a second portion of a bone, the first and second portion of the bone being located either side of a bone discontinuity, and wherein the elongate portion spans the bone discontinuity.

In another aspect of the invention, there is provided a method of treating a clavicle fracture, the method comprising performing surgery to secure the bone plate of any preceding claim to a clavicle bone, the clavicle bone having a fracture and the bone plate spanning said fracture and thus securing the fracture and allowing the fracture to heal. DESCRIPTION OF THE FIGURES

The invention will be described, by way of example only, and with reference to the accompanying figures, in which:

Figure 1 shows the anatomical structures that can affect plate fixation of the medial end of the clavicle bone.

Figure 2 shows a plan view of a bone plate in untwisted form.

Figure 3 shows an end-on view of a bone plate in untwisted form.

Figure 4 shows a twisted lateral clavicle locking plate of the invention.

Figure 5 shows a typical clavicle fracture prior to treatment.

Figure 6 shows the union of a typical clavicle fracture after use of a bone plate of the invention.

Figure 7 shows a typical clavicle fracture before and after fixation with a bone plate of the invention.

Figure 8 shows patient demographic and outcome data for those who have received a bone plate of the invention.

Figure 9 shows perspective views of an exemplary example of a bone plate of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be further described. In the following passages different aspects of the invention are defined in more detail. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous. In brief, the present invention provides a bone plate for securing a bone discontinuity, wherein the bone plate is twisted about its longitudinal axis such that the first and second securing portions lie in different planes about that axis.

Examples of such bone plates can be seen in Figure 4. Figure 4 shows twisted lateral clavicle locking plates 100 in use on a clavicular bone 200 having a medial end 201 and a lateral end 202. For reference, Figures 2 and 3 show the lateral clavicle locking plates in their untwisted form.

In each example, the bone plate 100 has a first securing portion 101 , a second securing portion 102, and an elongate portion 103 between the first and second securing portions, with a tapering of the plate width along its width from the first securing portion to the elongate portion. The first securing portion 101 , second securing portion 102 and elongate portion 103 all have holes 104 for receiving screws. This allows for the first securing portion 101 to be secured to the medial end of the bone 201 , the elongate portion 103 to be secured to the area of the bone where the fracture may be located 203, and the second securing portion to be secured to the lateral end of the bone 202. This allows for secure fixation of bone plate 100 to a left clavicle bone 200. (A) and (B) show a shorter plate with 13 holes 104 for receiving screws, whereas (C) shows a longer plate with 16 holes 104 for receiving screws.

This bone plate provides a number of advantages and these advantages are described and exemplified herein.

For example, fixing the medial end of the clavicular bone using a straight plate requires some compromise. If a straight plate is positioned on the superior aspect of the clavicle bone the sternoclaedomastoid muscle (SCM) insertion can be damaged by drilling and fixing the plate, and there is the potential for vascular compromise due to the high vascular network in this region (see Figure 1 B) and there is difficulty in drilling and inserting the screws perpendicular to the plate as the head and neck (particularly the skull) are in the way (see Figure 1A). If a straight plate is positioned on the anterior surface of the clavicle there is also a risk of damage to the vascular structures posterior to the clavicle (see Figure 1 C). To address these concerns, we bent same-sided lateral clavicle plates through 90° around their axis at the junction between the flared and shaft parts. By carefully contouring and controlling the bend, it was possible to align the shaft end of the plate along the superior surface of the clavicle, accurately accommodating the sternal curvature for both short and long plates (Figure 2). Acumed distal locking plates were used because this is the plating system that typically used for clavicular fractures. However there is no specific reason why any other proven clavicle distal locking plate made by another manufacturer could not have been used. Through an inferior anterior approach, to improve cosmesis and minimize wound irritation, the flared end of the plate could be positioned over the anterior surface of the medial end of the clavicle, permitting an unhindered drill trajectory and screw insertion to every screw hole available within the plate. The only compromise is that the preset peripheral locking screw angles in the plate are divergent to accommodate the broader, superior surface of the lateral clavicle. The anterior surface of the medial end of the clavicle is less broad, and some of the peripheral holes may require non-locking screws. A further benefit of the plate of the invention is that the twisted shape of the bone plate allows for the use of locking bicortical screws in the portion of the plate which is fixed to the bone in a plane wherein drilling is not in the direction of important anatomical structures. In the case of a medial end clavicle fracture, this is the non-broadened/flared portion of the plate which is fixed to the superior surface of the clavicle bone, lateral to the fracture, and can therefore use bicortical screws. On the other hand, the broadened portion of the plate can be sufficiently fixed to the bone, medial to the fracture, using multiple smaller unicortical screws, providing strong fixation whilst avoiding damage from drilling towards posterior anatomical structures. Therefore, the twisted bone plate of the invention offers accurate insertion without compromising important structures that insert into the bone, as well as providing improved access for screwing of the plate.

Secondly, the plate of the present invention provides a better fit to the bone than is seen with existing plates (particularly relatively long plates), as there is no “angular mis match”. Further, as described herein, there are decreased complications following the surgery because fixation with the bone plate of the present invention will be more successful than non-twisted bone plates. A more effective bone fixation ultimately allows for better patient recovery, as well as improved cosmesis, and indeed none of the patients that have been treated with a twisted bone plate of the invention have experienced or reported a complication. Although two patients felt that their metalwork was slightly prominent, they chose not to have this removed. Notably, all patients said that they would be happy to undergo the procedure again if a similar fracture were to occur on the contralateral side.

Successful bone fixation and avoidance of key anatomical features also allows successful repair whilst retaining normal joint movement. This can be seen in Figures 5 and 6, which show anteroposterior x-ray (A) and 3 dimensional reconstruction computed tomography scan (B) images of a patient with a comminuted fracture of the medial end of left clavicle (Figure 5), and the same patient six months post-surgery (Figure 6) having been treated with a twisted clavicle plate such as the one represented in Figure 4, demonstrating the fitting of the plate to the bone and successful union of the fracture. Similarly, Figure 7 shows serial plain x-ray images and an axial computed tomography scan of a right medial end clavicular fracture before and after fixation. At 4 weeks after fixation, there is still evidence of an inferior cortical discontinuity. At 4 months after fixation, callus can be seen inferiorly bridging the fracture with cortical continuity. Flowever, at 6 months there has been further consolidation of the fracture healing.

Figure 8 further demonstrates the success of such bone plates in a small clinical study of 8 patients (IA = intra-articular; EA = extra-articular; QuickDASFI = 11 -item version of the Disabilities of the Arm, Shoulder and Fland; M = male; R = right; SH II = Salter- Harris II; L = left; F = female; # = fracture). Surgical databases were searched and 8 patients were identified who underwent an open reduction and internal fixation using a contoured locking plate for an acute displaced medial fifth clavicular fracture. Exclusion criteria included an additional associated injury to the shoulder girdle (clavicle or scapula), previous clavicular fracture or injury to the sternoclavicular joint (SCJ), and a delayed or established non-union. One patient had a Salter- Harris II fracture that was displaced posteriorly. Due to his relative maturity (16 years), the amount of displacement, and that he was playing rugby at an elite level, there was concern that his fracture, if it were treated non-operatively and did unite, might not significantly remodel and result in a functionally impairing mal-union. The mean score on the 11 -item version of the Disabilities of the Arm, Shoulder and Fland, a primary outcome of the study, was 0.6 (range, 0-2.3). All patients had returned to their preinjury level of sport, activity, study, or work and had regained a full and equal range of motion at their SCJ compared with the non-injured side. Seven patients had regained a full and equal range of motion at their glenohumeral joint compared with the other side. Before the clavicular injury, 1 patient had undergone a surgical anterior stabilization of the glenohumeral joint on the same side as the fracture. The patient did have some loss of external and internal rotation at the glenohumeral joint compared with the non-injured side but felt that this was no different to the range before the clavicular fracture. Hence the use of a twisted bone plate of the invention offers an advantage in effective fixation whilst retaining normal joint movement.

There are a few points to be taken into consideration when using such a plate. Although there are a number of benefits in drilling and inserting the screws into the anterior surface of the medial clavicle, care should be taken that the drill does not penetrate the posterior cortex of the clavicle and that the screws remain unicortical. The technique also requires careful contouring of the plate around its axial plane.

Further to the twisted bone plate as shown in Figure 2, we have made further improvements to the twisted plate in order to better fit to the clavicle bone, and in particular the medial end of the clavicle bone. The improved bone plate 100 can be seen in Figure 11 in use on clavicular bone 200 having a medial end 201 and a lateral end 202.

The bone plate 100 has a first securing portion 101 , a second securing portion 102, and an elongate portion 103 between the first and second securing portions, with a rapid step down in width along the length between the first securing portion 101 and the elongate portion 103, creating a narrowed portion 105. The first securing portion 101 , second securing portion 102 and elongate portion 103 all have holes 104 for receiving screws. This allows for the first securing portion 101 to be secured to the medial end of the bone 201 , the elongate portion 103 to be secured to the area of the bone where the fracture may be located 203, and the second securing portion to be secured to the lateral end of the bone 202. This allows for secure fixation of bone plate 100 to a left clavicle bone 200.

An advantage of this embodiment is that the first securing portion 101 is broadened, allowing for an increased amount of holes 104 for receiving screws, in this embodiment there are three rows of three holes 104 for receiving screws to provide improved fixture to a bone 200, particularly at the medial end of said bone 201 . This is especially important when the fracture occurs at the medial end of the bone 201 , as there is often a small area of bone that a plate can be secured to. Another advantage is that the first securing portion 101 is also contoured 105 to fit the curvature of the medial end of the bone 201 . This allows for better fitting to the anterior side of the medial end of the clavicle bone 201. A further advantage is that the rapid step down in width along the length between the first securing portion 101 and the elongate portion 103 results in a narrowed portion 105 allowing for a better fit to the bone with a reduction in the overall size of the plate.

While the foregoing disclosure provides a general description of the subject matter encompassed within the scope of the present invention, including methods, as well as the best mode thereof, of making and using this invention, the following examples are provided to further enable those skilled in the art to practice this invention and to provide a complete written description thereof. However, those skilled in the art will appreciate that the specifics of these examples should not be read as limiting on the invention, the scope of which should be apprehended from the claims and equivalents thereof appended to this disclosure. Various further aspects and embodiments of the present invention will be apparent to those skilled in the art in view of the present disclosure. It will therefore be clear to the skilled person that the inventive concept (i.e. a twisted bone plate) can be applied in a variety of contexts wherein fixation of a bone discontinuity is desired. For example, the bone plate of the present invention can be used advantageously to fix a fracture in other bones, such as the humeral shaft. The use of the bone plate of the present invention to fix a fracture in the humeral shaft allows for the avoidance of a neurological structure called the radial nerve, which twists around the humeral shaft from medial to lateral and is in danger of being damaged during certain surgical approaches. Care must be taken to find this nerve and, on occasion, it is necessary to mobilise the nerve and pass the plate under it. This is particularly for posterior and anterior-lateral approaches. A twisted plate may avoid this.

References

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Bartonicek J, Fric V, Pacovsky V. Displaced fractures of the medial end of the clavicle: report of five cases. J Orthop Trauma 2010; 24:e31 -5. Corrales LA, Morshed S, Bhandari M, Miclau T 3rd. Variability in the assessment of fracture-healing in orthopaedic trauma studies. J Bone Joint Surg Am 2008;90:1862-8.

Fransen P, Bourgeois S, Rommens J. Kirschner wire migration causing spinal cord injury one year after internal fixation of a clavicle fracture. Acta Orthop Belg 2007;73:390- 2.

Gille J, Schulz A, Wallstabe S, Unger A, Voigt C, Faschingbauer M. Hook plate for medial clavicle fracture. Indian J Orthop 2010;44:221 -3

Gummesson C, Ward MM, Atroshi I. The shortened Disabilities of the Arm, Shoulder and Hand questionnaire (QuickDASH): validity and reliability based on responses within the full-length DASH. BMC Musculoskelet Disord 2006;7:44.

Kim KC, Shin HD, Cha SM. Surgical treatment of displaced medial clavicle fractures using a small T-shaped plate and tension band sutures. Arch Orthop Trauma Surg 2011 ;131 :1673-6.

Low AK, Duckworth DG, Bokor DJ. Operative outcome of displaced medial-end clavicle fractures in adults. J Shoulder Elbow Surg 2008;17:751 -4.

Morshed S, Corrales L, Genant H, Miclau T 3rd. Outcome assessment in clinical trials of fracture-healing. J Bone Joint Surg Am 2008;90(Suppl. 1):62-7.

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Claims

CLAIMS:

1. A bone plate for securing a bone discontinuity, comprising; a first region with a first securing portion; a second region with a second securing portion; and an elongate portion between the first and second securing portions; wherein the plate is twisted about its longitudinal axis such that the first and second securing portions lie in different planes about the axis.

2. The bone plate of claim 1 , wherein the plate is twisted about its longitudinal axis at an angle such that the first securing portion lies in a plane that is perpendicular to the second securing portion.

3. The bone plate of claim 1 , wherein the plate is twisted about its longitudinal axis through 90°.

4. The bone plate of claim 1 , wherein a surface of the plate that, in use, contacts a bone, is contoured to fit the curvature of the bone.

5. The bone plate of claim 1 , wherein the bone plate is made of made of biocompatible material, high-grade titanium, titanium alloy or stainless steel.

6. The bone plate of claim 1 , wherein the first and second securing portions each comprise at least one hole for receiving a screw.

7. The bone plate of claim 6, wherein the elongate portion also comprises at least one hole for a screw for securing the elongate portion to a bone.

8. The bone plate of claim 1 , wherein the first or the second securing portion is broadened or flared.

9. The bone plate of claim 8, wherein the width of the plate tapers along at least a portion of the elongate portion from the broadened or flared first or second securing region towards the other of the second of first securing region.

10. The bone plate of claim 8, wherein the width of the plate steps down at the interface between the broadened or flared first or second securing region and the elongate portion.

11. A bone plate according to any preceding claim, wherein, in use, the bone discontinuity is located at the end portion of a bone.

12. The bone plate of claim 11 , wherein the bone discontinuity is a medial end clavicular fracture.

13. A bone plate according to any preceding claim, wherein, in use, the first securing region is secured to a first portion of a bone, the second securing region is secured to a second portion of a bone, the first and second portion of the bone being located either side of a bone discontinuity, and wherein the elongate portion spans the bone discontinuity.

14. A method of treating a clavicle fracture, the method comprising performing surgery to secure the bone plate of any preceding claim to a clavicle bone, the clavicle bone having a fracture and the bone plate spanning the fracture thus securing said fracture and allowing said fracture to heal.