Arch Orthop Trauma Surg DOI 10.1007/s00402-014-1952-5
Trauma Surgery
The interference of distal humeral plating with the medial and lateral collateral ligaments of the elbow Kilian Wegmann · K. J. Burkhart · J. Zimmermann · J. Dargel · S. Nijs · M. A. Konerding · L. P. Müller
Received: 24 October 2013 © Springer-Verlag Berlin Heidelberg 2014
Abstract Introduction The aim of the present study was to determine the anatomical relationship and evaluate the potential interference of today’s common distal humerus plates with the medial and lateral collateral ligaments of the elbow. Materials and methods The elbow joints of 23 embalmed upper extremities were dissected. Three different brands of distal humerus double-plating systems were applied in a standardized fashion. We used a caliper to measure the amount of absolute overlap of the plates on the corresponding collateral ligaments. Results The data show contact and overlap with the medial and lateral collateral ligaments in all tested medial and lateral plates. The posterolateral and posteromedial plates showed no contact with the ligaments, yet they did contact the posterior joint capsules. The medial plates showed less contact/overlap when compared with the lateral and extended medial plates. Conclusion Based on the present data, we conclude that distal humerus plating using the perpendicular technique with standard-sized medial plates shows the least amount of overlap over the medial and lateral collateral ligaments.
K. Wegmann (*) · K. J. Burkhart · J. Zimmermann · J. Dargel · L. P. Müller Center for Orthopaedic and Trauma Surgery, University Medical Center, Cologne, Germany e-mail: kilian.wegmann@uk‑koeln.de S. Nijs Department of Trauma Surgery, University Hospital of the Catholic University of Leuven, Louvain, Belgium M. A. Konerding Institute of Functional and Clinical Anatomy, University Medical Center, Johannes Gutenberg-University, Mainz, Germany
The extent of the overlap of the ligaments by the humeral plates is clearly shown in the present study. Keywords Distal humerus · Double plating · Collateral ligaments · Iatrogenic injury · Elbow instability
Introduction The medial and lateral collateral ligament complexes play a significant role in the stability and adequate function of the elbow joint [1]. In addition to the ligamentous structures, the osseo-cartilaginous structures of the articulating components function as passive primary stabilizers, where muscles crossing the joint act as dynamic stabilizers [2]. On the medial side, the medial collateral ligament (MCL) is subdivided into anterior, posterior and transverse bundles, of which the anterior bundle is the primary restraint to valgus stress; the transverse bundle apparently does not contribute to joint stability [3]. On the lateral side, the lateral collateral ligament (LCL) separates into the annular ligament (AL), the radial collateral ligament (RCL) and the lateral ulnar collateral ligament (LUCL). The LCL complex resists varus deviation and prevents posterolateral rotatory instability [4]. Iatrogenic injury during surgical procedures of the distal humerus can lead to relevant ligamentous insufficiency and functional instability. Lu et al. [5] recently reported three cases of patients with bi-columnar distal humerus fractures, who presented post-operative insufficiency of the LCL complex, thereby resulting in ulno-humeral instability. The treatment of distal humeral fractures often necessitates open reduction and internal fixation with plates. According to the conventional technique promoted by the Arbeitsgemeinschaft für Osteosynthesen, this is performed
13
Arch Orthop Trauma Surg
Fig. 1 Exemplary illustration of the measurements at the distal humerus. a Lateral plate application on a specimen. The plate is in contact with the LCL, but there is no overlay, thus adding to category 2. The contact is magnified in the upper left of the picture. b The distal hole of the plate comes to rest on the radial collateral ligament, thus adding to category 3 b
by the direct application of double plates to the medial and posterolateral part of the distal humerus, which is referred to as 90° or perpendicular plating [6]. In contrast to the conventional fixation methods promoted by the AO, O’Driscoll et al. claimed that the positioning of the plates in distal humerus fractures should be performed at a 180° orientation to obtain higher primary stability of the internal fixation than plating performed in a 90° orientation [7]. However, the plates have the potential to interfere with or damage the lateral and MCLs of the elbow. The aim of the present study was to analyze the anatomical relationship between standard implants and the lateral and MCLs, thereby revealing a possible compromise of the referred structures in the course of fracture treatment. We hypothesized that the plates come into considerable contact and overlap with the medial and lateral ligaments. The present study has been revised and acknowledged by the local ethics committee.
Materials and methods Specimens and analysis In the present study, 23 embalmed human cadaveric upper extremities from six men and six women with an average age of 81.6 years were available for the investigation. Upon examination, 23 of the 24 specimens presented with an adequate range of motion and ligamentous stability of the elbow joint. One specimen was discarded due to restricted range of motion by extensive degenerative changes of the joint, which were seen on fluoroscopic images. After soft tissue dissection, beginning superior to the medial epicondyle, only the joint capsule of the elbow and the collateral ligaments were preserved. To analyze the relative position between the pre-contoured distal humeral plates and the ligamentous structures
13
Table 1 Scoring system 1 No contact between implant and ligamentous structures 2 Plates are in contact with the ligamentous structures 3A Implant seated on ligamentous structures 3B Implant seated on ligamentous structures and screws penetrating the ligaments
of the elbow, different implants (see below) were properly applied to the cadaver specimens as recommended by the manufacturers (Fig. 1). The position of the implants was done by achieving the optimal fit of the anatomically precontoured plates according to the bony structures of the epicondyles or the posterior aspect of the humerus, respectively. The relative positions of the implants to the RCL, to the LUCL of the LCL, and to the anterior (AML) and posterior bundles (PML) of the MCL were measured. A scoring system was developed to define the amount of interference between the implant and the medial and lateral collateral ligaments (Table 1). In category 1 cases, there was no contact between the plates and the ligaments. In category 2, the plates were in contact with the ligaments, but without overlap. If the plates were seated on the medial and lateral ligaments of the elbow, they were assigned to category 3, and the absolute amount of overlap was measured in millimeters. Category 3 was further divided into subgroups (A and B) to identify implants in which the screws would not (A) or would (B) penetrate the ligamentous structures when applied properly. The absolute distances were measured using a caliper gauge providing an accuracy of 0.1 mm. The investigators performed these analyses at 90° of elbow flexion and in neutral rotation. Investigated implants Three different brands of implants (Acumed, Medartis and Stryker) were investigated (Fig. 2).
Arch Orthop Trauma Surg
Fig. 2 Example photographs of the tested distal humerus plates of each brand (a Stryker, b Acumed, c Medartis)
Medartis
Stryker
The Medartis osteosynthesis plates for the distal humerus were still in the process of development but were available free of charge for clinical investigations. We tested:
The Stryker plates allow parallel and perpendicular plating of the distal humerus, and medial and extended medial plates are available. Moreover, the Stryker plates offer inverted perpendicular plating in the form of a combined posteromedial and lateral plating option. We tested:
–– Medartis medial plate (MMP, 10-hole locking plate; 86 mm length). –– Medartis lateral plate (MLP, 13-hole locking plate; 84 mm length). –– Medartis posterolateral plate (MPLP, 13/15-hole locking plate; 83 mm length). The plates offer options for parallel and perpendicular plating and variable locking options. The Medartis posterolateral plate offers an additional stabilization option via a rectangular strap. The strap can be removed if it is not needed or not adequately adaptable to the accordant anatomical situation. We removed the strap because it interfered with joint mobility at the posterolateral aspect. Acumed The Acumed plates comprise a fixation system of parallel plating with a specific screw system that offers variable locking angles. We tested:
–– Stryker medial plate (SMP, 4-shaft hole locking plate; 92 mm length). –– Stryker extended medial plate (SEMP, 4-shaft hole locking plate; 96 mm length). –– Stryker lateral plate (SLP, 4-shaft hole locking plate; 109 mm length). –– Stryker posterolateral plate (SPLP, 4-shaft hole locking plate; 105 mm length). –– Stryker posteromedial plate (SPMP, 4-shaft hole locking plate; 104 mm length). We used the shortest available plate of each type for the present study. The plate lengths differ in longitudinal direction, in that an increasing size extends more proximally and therefore does not influence the anatomical relationship to the medial and lateral ligaments. The plates of different lengths of each brand do not differ in width or thickness. Statistical analysis
–– Acumed medial plate (AMP, 7-hole locking medial plate; 84 mm length). –– Acumed extended medial plate (AEMP, 9-hole locking medial plate; 95 mm length). –– Acumed lateral plate (ALP, 6-hole locking lateral plate; 58 mm length).
The statistical analysis was performed using IBM SPSS Statistics© version 19 (SPSS Inc., Chicago, IL, U.S.A.). The Kolmogorov–Smirnov test was performed to evaluate a normal distribution of the data. Because the data were not normally distributed, the Wilcoxon test was used to analyze
13
differences in the amount of overlap of the medial and lateral ligaments by the different plates. We analyzed whether there were differences between the medial, extended medial, lateral, posterolateral and posteromedial plates and if there were differences in the amount of contact with or overlap of the specific subdivisions of the medial and collateral ligaments. For the statistical analysis, the absolute amount of overlap in mm was used. Therefore, the results of category 1 and 2 were set as 0 mm. A p value <0.05 was considered to be significant.
Results According to the scoring system, the interference between the double plates and the medial and lateral ligaments was determined (Fig. 3). The absolute values in mm are given in Tables 2 and 3. Except for the posterolateral and posteromedial plates, which did not show any contact with the collateral ligaments, all of the tested implants contacted the medial and lateral ligamentous structures when applied properly. A significantly higher amount of overlap of the ligamentous structures with the lateral plates was observed when compared to the medial plates (p < 0.000). The posterolateral and posteromedial plates showed no contact with the ligaments. The highest amount of overlap was found by the extended medial plates, which was significantly higher than that for the other plates (p < 0.000). The analysis of the specific subdivisions of the MCLs demonstrated that, for the tested medial plates, there was significantly more contact with the AML than with the PML (p < 0.001). Conversely, for the extended medial plates, we found significantly more contact with the PML than with the AML (p < 0.001). The posteromedial plate had no contact with the MCL. Fig. 3 The anatomical relationship between the medial, lateral, extended medial, posteromedial and posterolateral plates and the medial and lateral collateral ligaments, according to the scoring system. The data are given in percent
13
Arch Orthop Trauma Surg
The Medartis medial plate showed significantly less overlap with the AML compared with the Acumed medial plate, Stryker medial plate, Acumed extended medial plate and Stryker extended medial plate (p < 0.001). The Acumed medial plate showed significantly less overlap than the Stryker medial plate, Acumed extended medial plate and Stryker extended medial plate (p < 0.001). The Acumed extended medial plate, Stryker extended medial plate and Stryker medial plate demonstrated a similar amount of AML overlap (p > 0.05). Concerning the PML, the Medartis medial plate and Acumed medial plate showed a comparable amount of overlap (p > 0.05), but the Acumed medial plate and Medartis medial plate showed a significantly lower amount of overlap than the Acumed extended medial plate, Stryker medial plate and Stryker extended medial plate (p < 0.001). An analysis of the specific subdivisions of the lateral collateral ligaments showed that the Stryker lateral plate had the greatest amount of lateral plate overlap of the LUCL (p < 0.001). The least amount of overlap within the lateral plates was found by the Medartis lateral plate (p < 0.001). The greatest amount of RCL overlap was found with the Stryker lateral plate (p < 0.001), while the least was found with the Medartis lateral plate (p < 0.001). The posterolateral plates were not in contact with the lateral collateral ligament.
Discussion Summarizing the present data, we conclude that distal humerus plates, which are commonly used in the treatment of fractures, have considerable contact and overlap with the medial and lateral collateral ligaments of the elbow joint. Moreover, statistically significant differences between the
0.2
SD
0.4
11.8 8.4 13.8 3.74
Extended medial plates
0.0
0.0 0.0 0.0 0.0 0.7
5.1 3.0 7.0 0.1 0.9
4.1 2.7 6.1 0.1 1
6.0 4.4 8.7 0.1 0.9
6.3 4.3 8.0 01
Acumed Stryker Medartis Posterome- Acumed extended medial medial dial plate medial plate -AML plate-AML plate -AML medial plate-AMI
0.7
6.6 5.1 7.7 0.1 1.4
0.0 0.0 3.2 0.2 1.4
0.0 0.0 3.0 0.2 1.8
31 0.0 4.4 0.3
Stryker Medartis Acumed Stryker medial medial medial exteuded plate-PML plate-PML plate-PML medial plate-AML
0.15
SD
Given in mm (n = 23)
7.4 6.2 8.4 0.51
Median Min Max Var.
0.0
0.0 0.0 0.0 0.0
Lateral plates Postero lateral plates
1
3.3 2.0 6.6 0.1
Acumed lateral plate-LUCL
1.4
3.0 0.0 3.8 0.2
Medartis lateral plate -LUCL
2.7
15.0 11.7 19.8 0.5
Stryker lateral plate-LUCL
0.8
5.2 4.0 6.9 0.1
Acumed lateral plate-RCL
0.9
4.3 2.8 6.1 0.1
1.8
14.0 10.2 17.3 0.3
Medartis -lateral Stryker lateral plate-RCL plate-RCL
3.6
12.9 5.2 17 1.3
0
0 0 0 0
0
0 0 0 0
Stryker posrerc-medial plate-AML/PML
0
0 0 0 0
Stryker posterolateral plate-LUCL/RCL
Stryker extended medial plate-PML
Medartis posterolateral plate -LUCL/-RCL
3.4
21.5 17 27 1.2
Acumed extended medial plate-PML
Table 3 Overview of the anatomic relations of the lateral plates to the lateral collateral ligaments and to the specific subdivisions of the collateral ligament
Given in mm (n = 23)
3.1 2.1 4.9 0.75
Median Min Max Var.
Medical plates
Table 2 Overview of the anatomic relations of the medial plates collateral ligaments and to the specific subdivisions of the collateral ligament
Arch Orthop Trauma Surg
13
tested plate profiles and their amount of contact and overlap with the medial and lateral collateral ligaments were found. Although fractures of the distal humerus seldom occur in adults, they are severe injuries of the upper extremities [8, 9]. Due to the aging populations in industrialized nations, these injuries are increasingly encountered. Treatment strategies generally focus on surgical procedures because of the specific challenges of the injuries of the distal humerus and the elbow joint [9]. An established treatment method for bi-columnar fractures of the distal humerus is open reduction and osteosynthesis by double plating. Only one clinical study has compared the outcomes of parallel and perpendicular plating in distal humeral fractures, and Shin et al. [10] found no significant differences between the two techniques. The present study focuses on the anatomical relationships between the commonly used distal humerus plates and the ligamentous stabilizers of the elbow joint. We found that all of the tested lateral and medial plates made contact with the investigated ligaments. As clearly demonstrated by our data, plate application to the medial and lateral epicondyles (180° plating) results in a greater area of overlap than the medial and posterolateral combination (90° plating). The posterolateral application of the according plates did not result in contact between the LCL and the plate. This was also true for posteromedial plating and the MCL. Nevertheless, the posterolateral and posteromedial plates contacted the posterior division of the joint capsule. In our opinion, contact between the plates and the posterior capsule has no clinical relevance because arthrolysis of the elbow joint by dissection of the joint capsule is a common treatment option that does not have a negative impact on elbow function [11]. There are limitations of the present study, like the caliper measurements that were done. When using a caliper, minimal measuring error cannot be evaded. On the other hand, to our knowledge, there is no other way to achieve the desired measurements more accurately. The results of the present study show highly significant differences between the plates and methods of application. It is unlikely that a minimal measuring error would influence the present data, in a way that the final conclusion would change. Another limitation represents the application of the plates. The placement of the plates was done with the intention, to achieve the best fit of the anatomical pre-contoured shape to the bony configuration of the distal humerus. This was the only way to achieve a standardized way of placement. Applying the plates in a way that they would have had the least amount of contact to the ligaments would have influenced the results for sure. Hence, the way of plate placement performed in the present study is reasonable. It is not known if deterioration of ligaments takes place as a result of contact with the plates. Elbow instability after double plating of the distal humerus is a rarely reported
13
Arch Orthop Trauma Surg
complication. Lu et al. [5] recently reported insufficient collateral ligaments after osteosynthesis of distal humerus fractures in three cases, leading to instability of the elbow. The authors suggested that the instability was either caused by the initial trauma, due to injury of the passive and active stabilizers, or during surgical treatment. The collateral ligaments of the elbow are subjected to joint movement due to their anatomic run. If the ligaments are fixed by an overlay of the plates or penetrated by the screws, injury during movement may take place. During flexion and extension, the ligaments could be irritated by the borders of the plate or by the inserted screws, thus leading to structural damage. The screws penetrating the ligaments may induce scarring of the tissue. Another possible mechanism of injury to the ligament might occur following compression of the ligamentous stabilizers by the plates. Also it is possible that the reduction of the working length of the ligaments by the mentioned mechanism might lead to stiffness. Compression might compromise the physiology of the ligaments. It cannot be said which consequence results from the contact between plates and ligaments, as it has to be analyzed in further projects. However, the study design does not allow judging whether hardware overlap onto the collateral ligaments of the elbow is detrimental. The discussed mechanisms were not investigated. By that, the clinical relevance of the aforementioned mechanisms of ligament lesions at the distal humerus remains unclear. One of the important findings of this current study is that when placing pre-contoured distal humeral plates, the surgeon should be cautious when dissecting the bed of the plates particularly at their distal ends, as this area of the plates is regularly in contact with the ligaments—at least with the medial and lateral plates. Extensive dissection at the bed of the plates can easily lead to ligament injury. One may try to place the plates differently not to overlap the ligaments. But as the plates might then loose contact to the humeral shaft there is only very little space to manoeuvre. The plates must, however, primarily be placed to achieve stable osseous fixation, secondarily placement in respect of the ligaments can be attempted. Having illustrated the close anatomical relationships between the MCL and LCL and the tested implants in the present study, we conclude that distal humerus plating using the perpendicular technique with standard-sized medial plates shows the least amount of overlap over the medial and lateral collateral ligaments. Moreover, significant differences between common distal humerus plates can be found, concerning the amount of contact and overlap with the medial and lateral collateral ligaments of the elbow joint and the chosen configuration of the plates seems to have significant impact onto the amount of overlap. These data can prove helpful for the surgeon when choosing the method of plate application in respect of the
Arch Orthop Trauma Surg
fracture configuration. Further evaluation of the interactions of hardware and the collateral ligaments of the elbow especially during movement will be necessary in the future to elucidate the interactions and to finally display the clinical relevance. Conflict of interest LPM, KJB, KW: The authors receive yearly payments as support for the work in the biomechanical laboratory by the MedartisTM. Moreover the authors receive travel support and payments for ongoing consultancy and fees for participation in review activities from MedartisTM.
References 1. O’Driscoll SW, Jupiter JB, King GJ, Hotchkiss RN, Morrey BF (2001) The unstable elbow. Instr Course Lect 50:89–102 2. Aksoy SM, Izdes S, Komurcu M, Bozkurt M, Basbozkurt M (2010) Utilization of axillary brachial plexus block in the postoperative rehabilitation of intra-articular fractures of the distal humerus. Acta Orthop Traumatol Turc 44(2):111–116. doi:10.394 4/AOTT.2010.2128 3. Jones KJ, Dines JS, Rebolledo BJ, Weeks KD, Williams RJ, Dines DM, Altchek DW (2013) Operative management of ulnar collateral ligament insufficiency in adolescent athletes. Am J Sports Med. doi:10.1177/0363546513507695
4. Dehlinger FI, Ries C, Hollinger B (2013) LUCL reconstruction using a triceps tendon graft to treat posterolateral rotatory instability of the elbow. Oper Orthop Traumatol. doi:10.1007/ s00064-012-0182-7 5. Lu HT, Guitton TG, Capo JT, Ring D (2010) Elbow instability associated with bicolumnar fracture of the distal humerus: report of three cases. J Hand Surg Am 35(7):1126–1129. doi:10.1016/j.jhsa.2010.04.007 6. Penzkofer R, Hungerer S, Wipf F, von Oldenburg G, Augat P (2010) Anatomical plate configuration affects mechanical performance in distal humerus fractures. Clin Biomech (Bristol, Avon) 25(10):972–978. doi:10.1016/j.clinbiomech.2010.07.005 7. O’Driscoll SW (2005) Optimizing stability in distal humeral fracture fixation. J Shoulder Elbow Surg 14(1 Suppl S):186S–194S. doi:10.1016/j.jse.2004.09.033 8. Weber O, Wirtz DC, Müller M, Kabir K, Burger C (2010) Die Ellenbogenfrakturprothese beim alten Menschen. Obere Extremität 5(1):20–26. doi:10.1007/s11678-010-0058-0 9. Miller AN, Beingessner DM (2013) Intra-articular distal humerus fractures. Orthop Clin N Am 44(1):35–45. doi:10.1016/j.ocl.2012.08.010 10. Shin SJ, Sohn HS, Do NH (2010) A clinical comparison of two different double plating methods for intraarticular distal humerus fractures. J Shoulder Elbow Surg 19(1):2–9. doi:10.1016/j.jse.2009.05.003 11. Dexel J, Kasten P (2013) Arthroskopie des Ellenbogens. Obere Extremität 8(1):2–8. doi:10.1007/s11678-013-0201-9
13
