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Scientific Articles   |    
Volar Locking Plate Implant Prominence and Flexor Tendon Rupture
Maximillian Soong, MD1; Brandon E. Earp, MD2; Gavin Bishop, MD3; Albert Leung, BS2; Philip Blazar, MD2
1 Lahey Clinic, 41 Mall Road, Burlington, MA 01805. E-mail address: mcsoong@gmail.com
2 Department of Orthopaedic Surgery, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115
3 Boston University Orthopaedic Surgery Residency, 715 Albany Street, DOB-808, Boston, MA 02118
View Disclosures and Other Information
Disclosure: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity.

Investigation performed at the Department of Orthopaedic Surgery, Lahey Clinic, Burlington, and the Department of Orthopaedic Surgery, Brigham and Women's Hospital, Boston, Massachusetts

Copyright © 2011 by The Journal of Bone and Joint Surgery, Inc.
J Bone Joint Surg Am, 2011 Feb 16;93(4):328-335. doi: 10.2106/JBJS.J.00193
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Abstract

Background: 

Flexor tendon injury is a recognized complication of volar plate fixation of distal radial fractures. A suspected contributing factor is implant prominence at the watershed line, where the flexor tendons lie closest to the plate.

Methods: 

Two parallel series of patients who underwent volar locked plating of distal radial fractures from 2005 to 2008 and with at least six months of follow-up were retrospectively reviewed. Group 1 included seventy-three distal radial fractures that were treated by three orthopaedic hand surgeons with use of a single plate design at one institution, and Group 2 included ninety-five distal radial fractures that were treated by four orthopaedic hand surgeons with use of a different plate design at another institution. On the postoperative lateral radiographs, a line was drawn tangential to the most volar extent of the volar rim, parallel to the volar cortical bone of the radial shaft. Plates that did not extend volar to this line were recorded as Grade 0. Plates volar to the line, but proximal to the volar rim, were recorded as Grade 1. Plates directly on or distal to the volar rim were recorded as Grade 2.

Results: 

In Group 1, the average duration of follow-up was thirteen months (range, six to forty-nine months). Three cases of flexor tendon rupture were identified among seventy-three plated radii (prevalence, 4%). Grade-2 plate prominence was found in two of the three cases with rupture and in forty-six cases (63%) overall. In Group 2, the average duration of follow-up was fifteen months (range, six to fifty-six months). There were no cases of flexor tendon rupture and no plates with Grade-2 prominence among ninety-five plated radii.

Conclusions: 

Flexor tendon rupture after volar plating of the distal part of the radius is an infrequent but serious complication. The plate used in Group 1 is prominent at the watershed line of the distal part of the radius, which may increase the risk of tendon injury. We found no ruptures in Group 2, perhaps as a result of the lower profile of the plate. Further studies are needed before recommending one plate over another. Regardless of plate selection, surgeons should avoid implant prominence in this area.

Level of Evidence: 

Therapeutic Level III. See Instructions to Authors for a complete description of levels of evidence.

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    References

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    These activities have been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the American Academy of Orthopaedic Surgeons and The Journal of Bone and Joint Surgery, Inc. The American Academy of Orthopaedic Surgeons is accredited by the ACCME to provide continuing medical education for physicians.
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    Maximillian Soong, MD
    Posted on May 20, 2011
    Dr. Soong responds to Mr. Brown
    Orthopaedic Surgeon, Lahey Clinic

    We appreciate the interest in our article. We completely agree with Dr. Brown that the surgeon plays an important role in plate positioning, as we state prominently in the final sentence of the abstract: "Regardless of plate selection, surgeons should avoid implant prominence in this area." Our article does not state, nor should be interpreted as indicating, that plate design is the sole predisposing factor in flexor tendon rupture. However, the surgeon's role does not negate our findings with regard to plate design. Indeed, Dr. Brown notes that "Due to this plate design all Acu-loc plates should be Grade 2 ... and all DVR plates should be Grade 0". He further states the opinion that "prominent metalwork" is the cause of tendon ruptures. Perhaps, based in part on design, each different plate has a different margin of error for placement.

    Thus, we all agree that both surgeon and implant factors are involved. Determining the relative importance of these factors will require further investigations. In our study, the presence of two parallel series with many similarities (number of surgeons, training of surgeons, number and types of fractures treated, length of follow-up) may have helped to control for surgeon-related factors, although a Level 1 design would clearly be superior. With regard to fracture reduction and plate position, while we did not formally assess initial reduction, we did assess for loss of reduction during follow-up, and we did assess plate position, including proximal/distal (Grade 1 vs. 2) and medial/lateral, as shown in Table III. We encourage Dr. Brown and colleagues to publish their work in these areas, to assist other surgeons in avoiding tendon complications, regardless of which plate they use.

    Regarding our reference to the series of 40 DVR cases without rupture, we agree that this is a small number, and thus the next sentence mentions a larger series of 87 DVR cases without rupture. Our own article includes another 95. We encourage other investigators to publish even larger series.

    Finally, readers should be aware that the latest generation of the Acumed plate, the "Acu-loc 2", now offers an alternative version which is positioned more proximally. We believe this change may help address the plate design issues that were the focus of our article.

    Daniel J. Brown
    Posted on May 20, 2011
    Volar Locking Plate Implant Prominence
    Orthopaedic Surgeon, Royal Liverpool University Hospital, United Kingdom

    To the Editor:

    I read with interest the article in your February edition by Soong et al. entitled, "Volar Locking Plate Implant Prominence and Flexor Tendon Rupture" (2011;93:328-35). Whilst I completely agree that flexor tendon ruptures are due to mechanical irritation on prominent metalwork, I am concerned that the authors' conclusions are an over-simplification and may put too much blame on the plate and too little on the surgeon by not considering other variables such as plate position and fracture reduction.

    The authors quote our published study on the prevalence on Flexor Pollicis Longus ruptures (FPL) (1) in stating that FPL ruptures occurred in 2.5% of cases of volar plating and correctly state that we did not have an FPL rupture in 40 cases with the DVR plate. To suggest that this fact supports their argument is misleading, however, as with a 2.5% prevalence in 40 cases it is as likely as not that we would have seen an FPL rupture with a DVR plate.

    Further, in our article we suggest that it is probably inaccurate plate position and fracture reduction that is more important in the etiology of ruptures than the design of plate itself. In subsequent, yet unpublished, research performed in this department and presented at IFSSH (2010) and BSSH (2009, 2010 & 2011), we have shown that inaccurate plate position and fracture reduction, as seen on intra- and post-operative radiographs, are strong predictors of FPL rupture and have demonstrated on cadaveric and dry bone models the significant effects of accuracy of plate position and fracture reduction on plate prominence (how much the free edge of the plate stands off the bone).

    Further, as mentioned in their paper, the Acu-loc plate is designed to sit more distally than the DVR plate, to provide more support for the radial styloid and provide more distal placement of screws, and this is demonstrated well in Figure 3 (p. 2) of their article. Due to this plate design all Acu-loc plates should be Grade 2 (using their system) and all DVR plates should be Grade 0. Acu-loc plates of Grade 0 or 1 have been put on too proximally and DVR plates of Grade 1 or 2 have been put on too distally (both of which, we have shown, causes statistically increased prominence compared with the position of best fit).

    It is my, belief, based upon our own research that the position of the plate and the quality of the reduction, both of which are under the surgeon's control, are more important than the design of the plate and I think blaming the design of the plate is misleading and dangerous. It is interesting that our paper presented the FPL ruptures associated with the first 201 procedures performed in our department; we have not, to my knowledge, had a further rupture in the subsequent 400 cases since we have been investigating the cause.

    References

    1. Casaletto JA, Machin D, Leung R, Brown DJ. Flexor pollicis longus tendon ruptures after palmar plate fixation of fractures of the distal radius. J Hand Surg Eur Vol. 2009;34:471-4.

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