Drobetz, Herwig (2012) Treatment of distal radius fractures with volar locking distal radius plates. PhD thesis, James Cook University.

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Abstract

Background: Distal radius fractures are the most common fractures of the human skeleton, with about ten per cent of the population sustaining a fracture at some point in their life. The traditional treatment of distal radius fractures was either non-operative, with closed reduction and cast immobilisation, or operative. Operative treatment options are open reduction and internal fixation or closed reduction and fixation with K-wires and/or an external fixator or cast. Until the late 1990s, open reduction and plate fixation was not a popular treatment option as plates inserted from the dorsal side frequently caused soft tissue complications and plates inserted from the volar side needed additional augmentation as a result of the biomechanical specifics of distal radius fractures. However, with the development of volar locking distal radius plates in 1997, considerable scientific, clinical and commercial interest in the treatment of distal radius fractures by open reduction and plate fixation has developed. The plates do have theoretical advances over other means of fixation as they allow early functional postoperative mobilisation, which might lead to faster recovery, which in turn might allow more expeditious return to work and/or to activities of daily life. I was fortunate to be part of the team that invented and implanted the first volar locking distal radius plate internationally; hence my interest in the treatment of distal radius fractures.

Overall aim of the studies presented in this thesis:

Primary aims (biomechanical):

• to achieve a better understanding of the biomechanical properties of distal radius volar locking plates – especially in view of the fact that dozens of different plate models are available with considerable differences in design and locking mechanisms

• to define optimal configuration, arrangement, placement and numbers of screws in volar locking plates

• to compare different plate systems in order to gain insight into the potential clinical behaviour of different locking mechanisms

Secondary aims (clinical):

The second aim of this thesis was to evaluate locking distal radius plates in various clinical studies (using real patients) in order to gain insight into the question of whether their outcome and complication rates are comparable to other methods of treatment.

Methods: The thesis comprises the result of eight biomechanical and clinical studies, which took place in Austria and Australia. The basis, foundation and initial study of this thesis is a retrospective clinical study conducted in Austria and presents the first international two-year results of experiences with volar locking distal radius plates. Based on this study seven biomechanical studies were performed. These studies tested various platescrew configurations and plate positions of volar locking distal radius plates in order to establish optimal screw number and diameter as well as position of the plate-screw construct relative to the radio-carpal joint line. The testing was performed partly with fresh-frozen cadaver wrists and partly with synthetic radii. The thesis further comprises the results of another clinical prospective multi-centre study relating to distal radial fracture management to which I contributed, being the principal investigator of Neunkirchen General Hospital, Austria.

Overall results and conclusions of the studies presented in this thesis:

Biomechanical studies: In order to achieve reproducible outcomes and minimise the loss of postoperative displacement, placement of the plate-screw construct as close as possible to the radio-carpal joint line is essential. Postoperative loss of reduction is directly proportional to the distance the distal screws are placed from the joint line. Despite the push for, and marketing of, multi-row implants with six to eight screws and up to three distal screw-rows in the T-part of the volar locking plates, biomechanical data do not show any benefit over implants incorporating a single distal screw row only. The overall diameter of the screws rather than the number seems to be the determining factor in terms of resistance to postoperative displacement. Constructs with threaded screws show significantly higher stability and rigidity than constructs with smooth pegs. Inserting an additional proximal screw close to the fracture line further increases stability.

Clinical studies: Treatment of distal radius fractures with volar locking plates allows early postoperative mobilisation with good reproducible radiographic and clinical results, with a limited number of complications. Clinical function and outcome do not appear to be associated with repair of a fracture of the base of the ulnar styloid. The treatment of distal radius fractures with volar locking plates is the only treatment currently available that allows immediate postoperative wrist motion without the need for additional fixation in most cases. There is, however, a need for prospective, randomised, controlled studies to establish whether treatment with volar locking distal radius plates is shown to be more beneficial than conventional treatment methods with regard to earlier return to function and activities of daily life in the short as well as in the long term. While there is a trend towards better outcomes, there is currently no evidence to show a clear advantage of volar locking plates over any other accepted form of treatment.

Overall relevance of the studies presented in this thesis:

Biomechanical Studies: The recommendations of one of my biomechanical studies was to place the distal locking screws as close as possible to the joint line to prevent postoperative loss of reduction. This has been accepted internationally as the clinical gold standard. Furthermore, I have shown that plates which incorporate more than one distal screw row do not have any biomechanical advantage over plates with a single distal screw row. Plate-screw constructs in which the distal screw row has an overall diameter of less than 12 millimetres display significantly less resistance to postoperative loss of reduction, which has implications for postoperative mobilisation protocols. Threaded locking screws are preferable to smooth locking pegs as they show significantly more resistance to postoperative displacement forces. In certain fracture types it might be beneficial to place a screw close to the fracture in the shaft part of the plate as this has been shown in biomechanical studies to cause less permanent deformation. However the clinical relevance of this finding still needs to be investigated.

Clinical Studies: The clinical studies presented in this thesis concluded that open reduction and internal fixation with volar locking plates produces good to excellent results in the majority of patients. The results are independent of the fracture severity, which means that meticulous technique, rather than fracture comminution or bone quality, is necessary to achieve good clinical results. The most pronounced improvements in function and pain are seen within the first twelve months. Furthermore, improved locking mechanisms, smooth titanium coating of the plates and rounded screw heads have shown a significant decrease in the number of tendon and soft tissue complications seen with first generation plates. It has also been shown that associated ulnar styloid fractures do not need to be repaired when stabilising distal radius fractures with volar locking plates.

Item ID:	29932
Item Type:	Thesis (PhD)
Keywords:	distal radius fractures; operative treatment options; locking mechanisms; biomechanics; plate screw configurations
Related URLs:	http://eprints.jcu.edu.au/29981/ http://eprints.jcu.edu.au/29982/ http://eprints.jcu.edu.au/26307/ http://eprints.jcu.edu.au/16490/ http://eprints.jcu.edu.au/29983/ http://eprints.jcu.edu.au/29984/ http://eprints.jcu.edu.au/29985/ http://eprints.jcu.edu.au/29986/ http://eprints.jcu.edu.au/30050/ http://eprints.jcu.edu.au/30051/ http://eprints.jcu.edu.au/30052/
Additional Information:	Restricted access - full thesis may either be requested via document delivery at your local library or viewed in the Eddie Koiki Mabo Library at JCU, Townsville. Chapter 2. Drobetz, H., and Kutscha-Lissberg, E. (2003) Osteosynthesis of distal radial fractures with a volar locking screw plate system. International Orthopaedics, 27 (1). pp. 1-6. Chapter 3. Drobetz, Herwig, Bryant, Adam L., Pokorny, Tom, Spitaler, Ralph, Leixnering, Martin, and Jupiter, Jesse B. (2006) Volar fixed-angle plating of distal radius extension fractures: influence of plate position on secondary loss of reduction: a biomechanic study in a cadaveric model. Journal of Hand Surgery, 31A (4). e1-e9. Chapter 4. Drobetz, Herwig, Weninger, Patrick, Grant, Caroline, Heal, Clare, Muller, Reinhold, Schuetz, Michael, Pham, Minh, and Steck, Roland (2013) More is not necessarily better: a biomechanical study on distal screw numbers in volar locking distal radius plates. Injury, 44 (4). pp. 535-539. Chapter 5. Drobetz, Herwig, Schueller, Michael, Tschegg, Elmar Karl, Heal, Clare, Redl, Heinz, and Muller, Reinhold (2011) Influence of screw diameter and number on reduction loss after plating of distal radius fractures. ANZ Journal of Surgery, 81 (1-2). pp. 46-51. Chapter 6. Weninger, Patrick, Dall'Ara, Enrico, Drobetz, Herwig, Nemec, Wolfgang, Figl, Markus, Redl, Heinz, Hertz, Harald, and Zysset, Philippe (2011) Multidirectional volar fixed-angle plating using cancellous locking screws for distal radius fractures: evaluation of three screw configurations in an extra-articular fracture model. Wiener klinische Wochenschrift, 123 (1-2). pp. 4-10. Chapter 7. Schüller, M., Drobetz, H., Redl, H., and Tschegg, E.K. (2009) Analysis of the fatigue behaviour characterized by stiffness and permanent deformation for different distal volar radius compression plates. Materials Science and Engineering C, 29 (8). pp. 2471-2477. Chapter 8. Weninger, Patrick, Schueller, Michael, Drobetz, Herwig, Jamek, Michael, Redl, Heinz, and Tschegg, Elmar (2009) Influence of an additional locking screw on fracture reduction after volar fixed-angle plating: introduction of the "protection screw" in an extra-articular distal radius fracture model. Journal of Trauma: injury infection & critical care, 67 (4). pp. 746-751. Chapter 9. Jupiter, Jesse B., and Marent-Huber, M. (2009) Operative management of distal radial fractures with 2.4-millimeter locking plates: a multicenter prospective case series. Journal of Bone and Joint Surgery, 91 (1). pp. 55-65. Appendix I: Weninger, Patrick, Dall'Ara, Enrico, Leixnering, Martin, Pezzei, Christoph, Hertz, Harald, Drobetz, Herwig, Redl, Heinz, and Zysset, Philippe (2010) Volar fixed-angle plating of extra-articular distal radius fractures: a biomechanical analysis comparing threaded screws and smooth pegs. Journal of Trauma: injury infection & critical care, 69 (5). E46-E55. Appendix II: Souer, J. Sebastiaan, Ring, David, Jupiter, Jesse B., Matschke, Stefan, Audige, Laurent, Marent-Huber, Marta, Hanson, Beate, Rikli, D., Siebert, H.R., Campbell, D.A., Teoh, L.-C., Torretta, F., Lauri, G., Hintringer, W., Drobetz, H., Plecko, M., Wentzensen, A., Höntzsch, D., Neugebauer, R.H., Haas, N.P., Rehm, K.E., Winker, K.H., Ertel, W., Sommer, Chr., Wagner, M., and Chow, S.P. (2009) Comparison of AO type-B and type-C volar shearing fractures of the distal part of the radius. Journal of Bone and Joint Surgery, 91 (11). pp. 2605-2611. Appendix III: Souer, J. Sebastiaan, Ring, David, Matschke, Stefan, Audige, Laurent, Marent-Huber, Marta, Jupiter, Jesse B., Hanson, Beate, Rikli, D., Siebert, H.R., Campbell, D.A., Lam-Chuan, Teoh, Torretta, F., Lauri, G., Hintriger, W., Drobetz, H., Plecko, M., Wentzensen, A., Höntzsch, D., Neugebauer, R.H., Haas, N.P., Rehm, K.E., Winker, K.H., Ertel, W., Sommer, Chr., Wagner, M., and Chow, S.P. (2009) Effect of an unrepaired fracture of the ulnar styloid base on outcome after plate-and-screw fixation of a distal radial fracture. Journal of Bone and Joint Surgery, 91 (4). pp. 830-838.
Date Deposited:	30 Apr 2014 04:56
FoR Codes:	11 MEDICAL AND HEALTH SCIENCES > 1106 Human Movement and Sports Science > 110601 Biomechanics @ 50% 11 MEDICAL AND HEALTH SCIENCES > 1103 Clinical Sciences > 110314 Orthopaedics @ 50%
SEO Codes:	92 HEALTH > 9201 Clinical Health (Organs, Diseases and Abnormal Conditions) > 920118 Surgical Methods and Procedures @ 50% 92 HEALTH > 9201 Clinical Health (Organs, Diseases and Abnormal Conditions) > 920116 Skeletal System and Disorders (incl. Arthritis) @ 50%
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