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Supplemental Superior Buttress Plating for the Treatment of Posterosuperior Wall Acetabulum Fractures

Askam, Brad MD; Sims, Stephen MD

doi: 10.1097/BOT.0000000000001394
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Summary: Posterosuperior wall acetabulum fractures are a unique and uncommon fracture pattern. Traditional plate fixation may not provide adequate fixation of these fracture fragments. This article presents a surgical technique and the results of a case series using a supplemental 1/3 tubular superior buttress plate to improve fracture reduction and better neutralize shear forces in the treatment of superior posterior wall fractures. Additionally, we compared failure rates of those posterior superior wall acetabular fractures treated with supplemental superior buttress plates to those treated with standard plate fixation and no supplemental superior buttress plates.

Department Orthopaedic Surgery, Atrium Health Musculoskeletal Institute, Charlotte, NC.

Reprints: Stephen Sims, MD, Department Orthopaedic Surgery, Atrium Health Musculoskeletal Institute, 1000 Blythe Boulevard, Charlotte, NC 28203 (e-mail: Stephen.Sims@atriumhealth.org).

S. Sims has received payment as a speaker from AO North America and Stryker. The remaining author reports no conflict of interest.

Accepted November 06, 2018

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INTRODUCTION

Originally described by Letournel as one of the 5 elementary patterns, fractures of the posterior wall are the most common type of acetabulum fracture, accounting for up to one-third of all acetabular fractures.1–5 A majority of these fractures are multifragmentary or associated with marginal impaction of the articular surface.2 These fractures have been recognized as a unique subtype, and Letournel described “posterosuperior fractures” as those in which part of the adjacent roof becomes separated (Figs. 1–4). This was a relatively rare fracture pattern in his series, accounting for 11.6% of the posterior wall fractures and 2.75% of all fracture patterns.2

FIGURE 1

FIGURE 1

FIGURE 2

FIGURE 2

FIGURE 3

FIGURE 3

FIGURE 4

FIGURE 4

Posterosuperior wall fractures have been identified as being at risk for failure and secondary displacement after operative fixation.6,7 The hip joint bears high loads, with a joint reactive force vector of 2.35 times body weight, and the posterior wall bearing 24% of this load.7 There are marked alterations in load transmission across the hip after a fracture of the posterior wall, with a decrease in total articular contact area leading to greater maximum pressure and contact force seen at the superior aspect of the acetabulum.8 This only serves to increase the high shear forces seen on fracture fragments involving the superior posterior wall. The importance of articular reduction has previously been demonstrated, with clinical outcomes shown to correlate with the ability to obtain and maintain anatomic articular reduction.2,9,10

To obtain adequate fixation in superior posterior wall fractures, Letournel stressed that the plate must be placed more anterior in the supracotyloid region.2 The purpose of this report is to describe the use of a separate superior buttress plate in addition to a standard posterior wall plate for the treatment of posterosuperior wall acetabulum fractures. Additionally, we compared failure rates of those posterior superior wall acetabular fractures treated with supplemental superior buttress plates to those treated with standard plate fixation and no supplemental buttress plates.

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TECHNIQUE

As for a standard posterior wall acetabulum fracture treatment, the patient is placed into the prone or lateral decubitus position with the operative hip extended and the knee flexed. A posterior approach to the acetabulum is performed using a Kocher–Langenbeck or modified Gibson approach.2,11

The posterior wall is reduced using described techniques and provisionally fixed.2,12 A superior buttress plate is placed at the anterior/superior apex of the posterosuperior wall fragment using a 2-, 3-, or 4-hole 1/3 tubular plate applied in buttress mode using standard AO technique (Figs. 5 and 6). It is positioned in such a way so that first screw inserted in the plate is placed just superior to the fracture apex (Fig. 5A). The 1/3 tubular plate placed in this position can assist with final reduction of the fragment and counteract the large shear forces seen on the superior posterior wall fragment. A standard posterior wall plate near the rim of the acetabulum is positioned over the fragment and extends from the ischium to beyond the most anterior extent of the superior wall fragment on the ilium in the supra-acetabular region (Figs. 5 and 6).11,12 It is felt the shear forces may not be adequately neutralized with the standard posterior wall plate alone, and tightening a slightly under-contoured plate may cause the superior apex of the fracture to hinge outward. If the fragment is very small, the posterior wall plate may overlie the superior wall buttress plate, but this situation was less common.

FIGURE 5

FIGURE 5

FIGURE 6

FIGURE 6

After adequate fixation of the posterior wall fracture fragments has been achieved, the digastric osteotomy, when performed, is reduced with a pointed reduction tenaculum and fixed using 2 or 3 3.5-mm cortical lag screws (Fig. 6).

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CLINICAL SERIES

Patients and Methods

After receiving local institutional review board approval, a retrospective chart review identified 342 operatively treated acetabulum fractures performed by a senior fellowship-trained orthopaedic traumatologist at a single urban level-1 trauma center between 2004 and 2017. Fractures were classified according to Letournel classification scheme,2 and we identified 112 elementary posterior wall fractures (33%). Further subclassification was performed to identify those involving posterosuperior wall. A posterosuperior wall fracture was defined having a fracture line extending anterior to the 12 o'clock position to include the roof of the acetabulum on sagittal CT imaging or those that extend cephalad to the superior margin of the greater sciatic notch. This wall fracture may consist of one or more fragments or include marginal impaction.2 We compared failure rates of those posterior superior wall acetabular fractures treated with supplemental superior buttress plates to those treated with standard plate fixation and no supplemental buttress plates. The primary outcome measure evaluated was failure, defined as the need for total hip arthroplasty anytime during the follow-up period.

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RESULTS

Of the 112 elementary fractures of the posterior wall, 31 (28%) fractures involved the posterosuperior wall. Patient age ranged from 20 to 60 years with a mean age of 41.3 years. Twenty-one (68%) of these patients were treated using a supplemental superior buttress plate with a mean follow-up of 3.4 years (range 0.1–13.6 years). Ten (32%) patients were treated without the addition of a superior buttress plate with a mean follow-up of 3.8 years (range 0.1–12.8 years). The addition of the supplemental superior buttress plate was more commonly used in response to observed failures seen with standard fixation.

The decision to perform a digastric trochanteric osteotomy was made on a case-by-case basis. Strong consideration for osteotomy was made for those fractures with extensive comminution of the posterior wall where additional anterior or cephalad exposure was felt to be necessary to reduce the fracture (Figs. 1–6). A digastric trochanteric osteotomy was used in 9 (43%) patients treated with superior buttress plate and 4 (40%) patients treated without addition of a buttress plate.

There was 1 (4.7%) failure in the supplemental superior buttress plate group with the patient requiring total hip arthroplasty because of post-traumatic osteoarthritis, without evidence of subluxation or dislocation postoperatively. There were 3 (30%) failures in the posterosuperior wall group treated without additional buttress plate. One patient dislocated postoperatively with persistent instability and required total hip arthroplasty. Two patients subluxated superiorly with development of osteoarthritis and required total hip arthroplasty. Although there were fewer failures in the supplemental buttress plate group (4.7% vs. 30%), this difference did not reach statistical significance (P = 0.052).

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DISCUSSION

Fractures of the posterior wall of the acetabulum remain the most common fracture pattern and often have a simple plain radiographic appearance that does not necessarily correlate with the complex nature of these fractures or their potential for poor outcomes.1–5 Reported risk factors for unsatisfactory outcomes include fracture comminution, marginal impaction, injury to the femoral head, involvement of the weight-bearing dome, and age greater than 55 years.10,13–15 The purpose of this article was to raise awareness of a unique fracture pattern and describe a fixation technique that offers a biomechanically advantageous fixation construct for the treatment of fractures involving the posterosuperior acetabular wall.

Fractures of the posterosuperior wall, extending anteriorly to involve the roof of the acetabulum, were recognized as a unique fracture pattern by Letournel.2 These fracture patterns are uncommon, accounting for 11.6% of elementary posterior wall fractures in Letournel series and 28% in our case series.2 Fractures involving the posterosuperior wall have been noted by Moed et al as a potentially important indicator of hip instability, and care must be taken to identify and adequately treat these fractures.6 Traditional plate fixation using a plate along the lateral rim, extending from the ischium to the ilium past the cephalad and anterior extent of the fracture, may not provide adequate fixation for fracture fragments in the superior portion of the acetabulum. The standard position of the posterior wall plates is not at a biomechanically ideal position to buttress the fracture, and without perfect or slight under contouring, this plate may not have maximal contact with the fracture fragment. The described superior wall buttress plate is placed in an optimal position to buttress the fracture fragment in a similar fashion as buttress plates used in partial articular fractures in other areas. The plate may be used to finalize the reduction of the fragment, as the first screw inserted in the plate is placed just superior to the fracture apex (Fig. 5A). In this way, it can serve to key in and compress the apex of the fracture.

We have described our surgical technique to address posterosuperior wall acetabulum fracture, a unique and uncommon fracture pattern, using a supplemental 1/3 tubular buttress plate applied at the apex of the fracture to counteract the high shear stresses placed on these fragments. It is vital to place the plate at the apex of this fracture so that it adequately serves as a true buttress plate. At times, this plate may sit under the traditional lateral rim plate or as an isolated plate (Figs. 5 and 6). In our series, the majority (68%) of fractures involving the posterosuperior wall were fixed using a supplemental superior buttress plate. Although the superior buttress plate group had fewer failures than those treated without a specific plate to address the superior posterior wall fragment (4.7% vs. 30%; P = 0.052), this difference did not reach statistical significance, likely due to the small number of patients in this series. Nevertheless, this report presents the largest series looking specifically at this injury and describes a valuable technique to aid fracture reduction and fixation using standard implants and treatment principles.

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REFERENCES

1. Judet R, Judet J, Letournel E. Fractures of the acetabulum: classification and surgical approaches for open reduction. J Bone Joint Surg Am. 1964;46:1615–1647.
2. Letournel E, Judet R. Fractures of the Acetabulum. Elson RA, ed. New York, NY: Springer; 1993.
3. Baumgaertner MR. Fractures of the posterior wall of the acetabulum. J Am Acad Orthop Surg. 1999;7:54–65.
4. Olson SA, Finkemeier CG. Posterior wall fractures. Op Tech Orthop. 1999;9:148–160.
5. Aho AJ, Isberg UK, Katevuo VK. Acetabular posterior wall fracture. 38 cases followed for 5 years. Acta Orthop Scand. 1986;57:101–105.
6. Grimshaw CS, Moed BR. Outcomes of posterior wall fractures of the acetabulum treated nonoperatively after diagnostic screening with dynamic stress examination under anesthesia. J Bone Joint Surg Am. 2010;92:2792–2800.
7. Moed BR, Spoonamore MJ. Management of acetabular fractures. In: Fairbank J, Bowden G, Buckwalter J, et al, eds. Oxford Textbook of Orthopedics and Trauma. Oxford, United Kingdom: Oxford Univ Pr; 2002:2182–2201.
8. Olson SA, Bay BK, Pollak AN, et al. The effect of variable size posterior wall acetabular fractures on contact characteristics of the hip joint. J Orthop Trauma. 1996;10:395–402.
9. Olson SA, Bay BK, Chapman MW, et al. Biomechanical consequences of fracture and repair of the posterior wall of the acetabulum. J Bone Joint Surg Am. 1995;77:1184–1192.
10. Matta JM. Fractures of the acetabulum: accuracy of reduction and clinical results in patients managed operatively within three weeks after the injury. J Bone Joint Surg Am. 1996;78:1632–1645.
11. Moed BR. The modified Gibson posterior surgical approach to the acetabulum. J Orthop Trauma. 2010;24:315–322.
12. Moed BR, McMichael JC. Outcomes of posterior wall fractures of the acetabulum: surgical technique. J Bone Joint Surg Am. 2008;90(suppl 2):87–107.
13. Moed BR, Willson Carr SE, Gruson KI, et al. Computed tomographic assessment of fractures of the posterior wall of the acetabulum after operative treatment. J Bone Joint Surg Am. 2003;85:512–522.
14. Moed BR, Willson Carr SE, Watson JT. Results of operative treatment of fractures of the posterior wall of the acetabulum. J Bone Joint Surg Am. 2002;84:752–758.
15. Saterbak AM, Marsh JL, Nepola JV, et al. Clinical failure after posterior wall acetabular fractures: the influence of initial fracture patterns. J Orthop Trauma. 2000;14:230–237.
Keywords:

posterosuperior wall acetabulum fractures; posterior wall acetabulum fracture treatment; posterior wall acetabulum fractures

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