Acetabular Fractures: A Problem-Oriented Approach.

The main goals of acetabular fracture management are to restore the congruity and stability of the hip joint. These goals are the same for all patients who have an acetabular fracture, regardless of the morphology or etiology of the fracture. Nevertheless, certain acetabular fracture types and several patient factors pose management challenges for surgeons. Therefore, surgeons who manage acetabular fractures must understand the distinctive features of acetabular fractures as well as the soft-tissue and patient-related factors that play a critical role in patient outcomes. Particular challenges in the management of acetabular fractures include acetabular fracture types that involve the posterior wall, acetabular fractures with soft-tissue concerns, acetabular fractures in patients with multiple injuries, and acetabular fractures in the geriatric population. Although the well-known protocols that were established by Judet and Letournel continue to be important guidelines for the management of acetabular fractures, the injury characteristics of acetabular fractures, the demographics of the patients in whom acetabular fractures occur, and the treatment options for acetabular fractures have evolved. Therefore, surgeons must be aware of new and more recently published information on acetabular fractures.

Does Modified Footwear Improve Gait After Ankle Arthrodesis?

Rocker bottom shoes are commonly recommended for patients who have undergone ankle arthrodesis. Limited data are available to support this recommendation. In the present case-control study, 2 groups of participants were identified for the investigation: a study group (SG) of 9 patients who had previously undergone ankle arthrodesis and a normal group (NG) of 9 healthy volunteers. Gait data were collected using a video recorder while the participants walked barefoot and wearing rocker bottom shoes. These data were analyzed using computer-based gait analysis software. The total motion was calculated and averaged for each group for walking barefoot and wearing rocker bottom shoes. All participants completed the Short Musculoskeletal Function Assessment and the American Orthopaedic Foot and Ankle Society questionnaires. The total motion of the SG wearing rocker bottom shoes increased 4.8° (range 3.4° to 6.9°) on mean average, an improvement compared with walking barefoot (p < .05). In the NG, the shoe wear had no effect on the total motion (p = .59). Although the total motion in the SG approached the mean average of the total motion of the NG, it remained significantly less than that of the NG (p < .05). Additionally, the SG scored worse than the NG on both outcomes questionnaires (p < .05). Rocker bottom shoes had no effect on gait velocity. In conclusion, rocker bottom shoes significantly improve the total motion of ankle arthrodesis patients toward normal.

Current management of posterior wall fractures of the acetabulum.

The general goals for treating an acetabular fracture are to restore congruity and stability of the hip joint. These goals are no different from those for the subset of fractures of the posterior wall. Nevertheless, posterior wall fractures present unique problems compared with other types of acetabular fractures. Successful treatment of these fractures depends on a multitude of factors. The physician must understand their distinctive radiologic features, in conjunction with patient factors, to determine the appropriate treatment. By knowing the important points of posterior surgical approaches to the hip, particularly the posterior wall, specific techniques can be used for fracture reduction and fixation in these often challenging fractures. In addition, it is important to develop a complete grasp of potential complications and their treatment. The evaluation and treatment protocols initially developed by Letournel and Judet continue to be important; however, the surgeon also should be aware of new information published and presented in the past decade.

Supplemental S1 fixation for type C pelvic ring injuries: biomechanical study of a long iliosacral versus a transsacral screw.

BACKGROUND: A single iliosacral screw placed into the S1 vertebral body has been shown to be clinically unreliable for certain type C pelvic ring injuries. Insertion of a second supplemental iliosacral screw into the S1 or S2 vertebral body has been widely used. However, clinical fixation failures have been reported using this technique, and a supplemental long iliosacral or transsacral screw has been used. The purpose of this study was to compare the biomechanical effect of a supplemental S1 long iliosacral screw versus a transsacral screw in an unstable type C vertically oriented sacral fracture model. MATERIALS AND METHODS: A type C pelvic ring injury was created in ten osteopenic/osteoporotic cadaver pelves by performing vertical osteotomies through zone 2 of the sacrum and the ipsilateral pubic rami. The sacrum was reduced maintaining a 2-mm fracture gap to simulate a closed-reduction model. All specimens were fixed using one 7.0-mm iliosacral screw into the S1 body. A supplemental long iliosacral screw was placed into the S1 body in five specimens. A supplemental transsacral S1 screw was placed in the other five. Each pelvis underwent 100,000 cycles at 250 N, followed by loading to failure. Vertical displacements at 25,000, 50,000, 75,000, and 100,000 cycles and failure force were recorded. RESULTS: Vertical displacement increased significantly (p < 0.05) within each group with each increase in the number of cycles. However, there was no statistically significant difference between groups in displacement or load to failure. CONCLUSIONS: Although intuitively a transsacral screw may seem to be better than a long iliosacral screw in conveying additional stability to an unstable sacral fracture fixation construct, we were not able to identify any biomechanical advantage of one method over the other.

CT-generated radiographs in obese patients with acetabular fractures: can they be used in lieu of plain radiographs?

BACKGROUND: Acetabular fracture diagnosis is traditionally made with AP and oblique pelvic plain radiographs. Obesity may impair diagnostic accuracy of plain radiographs. New CT reconstruction algorithms allow for simulated radiographs that may eliminate the adverse imaging effects of obesity. QUESTIONS/PURPOSES: In obese patients with acetabular fractures, we compared CT-generated and plain radiographs in terms of (1) ability to classify fracture type, (2) agreement in fracture classification, and (3) surgeon performance at different experience levels. METHODS: CT-generated and plain radiograph image sets were created for 16 obese (BMI>35) patients with 17 acetabular fractures presenting from 2009 to 2011. Three orthopaedic trauma attending physicians, three senior residents, and three junior residents independently viewed these sets and recorded their diagnoses. These diagnoses were compared to the postoperative findings, which we defined as the gold standard for diagnosis. To assess intraobserver reliability, the same observers reviewed a rerandomized set 1 month later. We had 80% power to detect a 25% difference in the percentage of correctly classified fractures based on a post hoc sample size calculation and 80% power to detect a 0.10 difference in κ value based on both a priori and post hoc sample size calculations. RESULTS: With the numbers available (153 observations in each image set, 51 for each of the three observer groups), we found no differences between CT-generated and plain radiographs, respectively, in terms of percentage of correct diagnoses for the observer groups (all observers: 54% versus 49%, p=0.48; attendings: 61% versus 59%, p=0.83; senior residents: 51% versus 53%, p=0.84; and junior residents: 49% versus 35%, p=0.16). Furthermore, agreement between CT-generated and plain radiographic fracture classifications was substantial (κ=0.67). Nonetheless, the attending and senior resident groups performed better in correctly classifying the fracture than the junior residents when using plain radiographs (p=0.01 and p=0.049, respectively). Performance was not different when comparing the attendings to the senior resident and junior groups or comparing the senior residents to the junior residents using CT-generated radiographs (p=0.32, p=0.22, and p=0.83, respectively). CONCLUSIONS: CT-generated radiographs are as good as plain radiographs for experienced surgeons for classifying acetabular fractures in obese patients. CT-generated imaging may be valuable in both teaching and clinical settings, and it may spare the patient additional radiation exposure and discomfort. LEVEL OF EVIDENCE: Level II, diagnostic study. See the Instructions for Authors for a complete description of levels of evidence.

A prospective randomized comparison of two skin closure techniques in acetabular fracture surgery.

BACKGROUND: Recent publications have shown an infection rate of 5-7 % for acetabular fractures treated with the Kocher-Langenbeck (K-L) approach. Using metallic staples to close hip skin incisions has been considered the gold standard. The purpose of this study was to answer the following: (1) will closure of a K-L incision after acetabular fracture surgery with a running subcuticular monocryl suture, then sealing the wound with 2-octyl cyanoacrylate (OCA), result in a lower infection rate compared to metallic staple closure? (2) Do incisions closed with subcuticular monocryl and OCA exhibit decreased drainage? (3) Is there a cost difference between these two methods? MATERIALS AND METHODS: In a prospective clinical study, 103 patients with acetabular fractures treated using the K-L approach were randomized into two groups: skin closure with metallic staples (n = 52) versus subcuticular running monocryl suture sealed with OCA (n = 51). RESULTS: Two postoperative deep infections (4 %) in the staples group required multiple debridements; no infections developed in the OCA group. However, there was no statistical difference between the groups, (p = 0.495). There was a statistically significant difference (p = 0.032) comparing days from surgery to a dry incision favoring OCA (4.2 versus 5.85 days). The patient charge was approximately $900 greater on average in the OCA group due to the increased time in the operating room required for the subcuticular closure. CONCLUSIONS: Closure with OCA and subcuticular monocryl showed no clinical disadvantages and appears to have a clinical advantage when compared to standard metallic staple skin closure in acetabular fracture surgery. However, additional patient costs may be incurred. LEVEL OF EVIDENCE: II.

CD271 as a marker for mesenchymal stem cells in bone marrow versus umbilical cord blood.

CD271 has been applied to isolate mesenchymal stem cells (MSCs) from bone marrow and other tissues. Umbilical cord blood is a unique resource of stem cells and endothelial progenitor cells. Isolation of MSCs from umbilical cord blood, however, has been inefficient and inconsistent. This study was designed to examine the potential application of CD271 as a marker for the isolation of MSCs from umbilical cord blood. CD271+ cells were isolated from umbilical cord blood and bone marrow using CD271 antibody-conjugated microbeads, and characterized in osteogenic, chondrogenic and adipogenic differentiation. CD271+ cells from umbilical cord blood were slow to proliferate compared with those isolated from bone marrow. While CD271+ cells from bone marrow differentiated into osteogenic, chondrogenic and adipogenic lineages, there were no sound indications of differentiation by CD271+ cells from umbilical cord blood under the same differentiation conditions applied to the CD271+ cells from bone marrow. The study also found that bone marrow CD271+ cells remarkably upregulated the expression of chondrogenic genes under chondrogenic differentiation induction. When implanted into bone defects in mice, CD271+ cells from bone marrow regenerated significant bone, but the counterparts in umbilical cord blood formed little bone in the bone defects. In conclusion, CD271 is an efficient marker for MSC isolation from bone marrow but has failed to isolate MSCs from umbilical cord blood. CD271+ cells in bone marrow are particularly chondrogenic. The property of CD271+ cells is unique but varies from different tissues.

Radiographic changes of implant failure after plating for pubic symphysis diastasis: an underappreciated reality?

BACKGROUND: Implant failure after symphyseal disruption and plating reportedly occurs in 0% to 21% of patients but the actual occurrence may be much more frequent and the characteristics of this failure have not been well described. QUESTIONS/PURPOSES: We therefore determined the incidence and characterized radiographic implant failures in patients undergoing symphyseal plating after disruption of the pubic symphysis. METHODS: We retrospectively reviewed 165 adult patients with Orthopaedic Trauma Association (OTA) 61-B (Tile B) or OTA 61-C (Tile C) pelvic injuries treated with symphyseal plating at two regional Level I and one Level II trauma centers. Immediate postoperative and latest followup anteroposterior radiographs were reviewed for implant loosening or breakage and for recurrent diastasis of the pubic symphysis. The minimum followup was 6 months (average, 12.2 months; range, 6-65 months). RESULTS: Failure of fixation, including screw loosening or breakage of the symphyseal fixation, occurred in 95 of the 127 patients (75%), which resulted in widening of the pubic symphyseal space in 84 of those cases (88%) when compared with the immediate postoperative radiograph. The mean width of the pubic space measured 4.9 mm (range, 2-10 mm) on immediate postoperative radiographs; however, on the last radiographs, the mean was 8.4 mm (range, 3-21 mm), representing a 71% increase. In seven patients (6%), the symphysis widened 10 mm or more; however, only one of these patients required revision surgery. CONCLUSIONS: Failure of fixation with recurrent widening of the pubic space can be expected after plating of the pubic symphysis for traumatic diastasis. Although widening may represent a benign condition as motion is restored to the pubic symphysis, patients should be counseled regarding a high risk of radiographic failure but a small likelihood of revision surgery. LEVEL OF EVIDENCE: Level IV, case series. See Guidelines for Authors for a complete description of levels of evidence.

Nonoperative Treatment of Posterior Wall Acetabular Fractures After Dynamic Stress Examination Under Anesthesia: Revisited.

OBJECTIVES: Performing an examination under general anesthesia (EUA) using dynamic stress fluoroscopy of patients with posterior wall acetabular fractures has been used as a tool to determine hip stability and the need for surgical intervention. The purpose of this study was to further evaluate the effectiveness of this technique, from a source other than its primary advocates, in patients with posterior wall acetabular fractures less than or equal to 50% who were stable on EUA and treated nonoperatively. DESIGN: Retrospective case series. SETTING: University Level 1 Trauma Center. PARTICIPANTS: Seventeen patients with a posterior wall acetabular fracture stable on EUA treated nonoperatively. INTERVENTION: The patients were treated nonoperatively as guided by an EUA negative for instability. Patient follow-up averaged 30 months (range, 6-64 months). MAIN OUTCOME MEASUREMENTS: Outcome evaluation included the modified Merle d'Aubigné clinical score and the Short Musculoskeletal Function Assessment Questionnaire. Radiographic evaluation for subluxation or arthritis consisted of the 3 standard pelvic radiographs. RESULTS: Radiographic evaluation showed all hips to be congruent with a normal joint space. Sixteen of the 17 patients had radiographic outcomes rated as "excellent"; 1 patient was rated "good." The modified Merle d'Aubigné score (obtained in 12 patients) averaged very good, with only 1 having less than a good (graded as fair) clinical outcome. The Short Musculoskeletal Function Assessment Questionnaire scores (from 11 patients) were not significantly different from normal and were within the normal reported values for all indices and categories. There was no correlation between fracture fragment size and outcome. CONCLUSIONS: This study further supports the contention that a stable hip joint, as determined by EUA, after posterior wall acetabular fracture treated nonoperatively is predictive of continued joint congruity, an excellent radiographic outcome, and good-to-excellent early clinical and functional outcomes. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Expression profile of carbonic anhydrases in articular cartilage.

Carbonic anhydrases (CAs), which catalyze the reversible reaction of carbonate hydration, are important for cartilage homeostasis. The full spectrum of CA activity of all 13 isoenzymes in articular cartilage is unknown. This study quantified the mRNA profile of CAs in rat articular cartilage, using quantitative polymerase chain reactions. Among the 13 functional CAs, CAs II, III, Vb, IX, XII and XIII were significantly expressed at mRNA level by the chondrocytes in articular cartilage. To verify these significantly expressed CAs in articular cartilage at protein level, immunohistochemistry was performed. While CAs III, Vb and XII distributed in the full-thickness of cartilage, including the calcified zone of cartilage, CA II was mainly localized in the proliferative zone of cartilage. CA IX was limited in the superficial zone of cartilage and CA XIII expressed in the superficial and partially mid zone. These results provide a framework for understanding individual CAs as well as the integrated CA family in cartilage biology, including matrix mineralization.

Can computed tomography predict hip stability in posterior wall acetabular fractures?

BACKGROUND: In a pilot study, two-dimensional (2-D) CT assessment of posterior wall fracture fragments predicted hip stability with small fracture fragments and instability for large fracture fragments. QUESTIONS/PURPOSES: To confirm the previous findings, we determined whether there is sufficient observer consistency and accuracy to predict hip stability in posterior wall acetabular fractures for this CT assessment method and assessed its ease of clinical use. METHODS: We selected 10 fractures having variable characteristics with known clinical outcome and created three study participant groups, based on level of training, for evaluation. Each observer reviewed the CT scans from the 10 fractures and applied the method in two separate sessions, the second after at least a 1-month washout period. RESULTS: Participants reported subjective ease in using the method, averaging 5 minutes (range, 3-11 minutes) for each assessment. Intraobserver and interobserver reliability were both greater than 0.80 regardless of the level of experience. Although sensitivity was 90%, specificity was only 61% after comparison with examination under anesthesia (EUA). Inappropriate nonoperative treatment would have occurred in 6% of cases and inappropriate operative treatment in 16%. CONCLUSIONS: This method for assessing hip instability is reliable, reproducible, and easy to learn and use. However, as a diagnostic tool in the clinical setting, it is useful only for fractures involving greater than 50% of the posterior wall owing to limited accuracy. For fractures less than 50%, EUA should be performed to determine hip stability.

Distinct functionalities of bone morphogenetic protein antagonists during fracture healing in mice.

The bone morphogenetic protein (BMP) family of growth factors plays critical roles in bone formation. BMPs are regulated at multiple levels by various BMP antagonists. This study investigated how BMP antagonists are integrated into the cascade of events of bone formation during fracture healing. Forty mice underwent a controlled femur fracture; tissue samples at the fracture site were harvested at days 1, 3, 7, 14 and 21 after fracture, for quantification of the expression of BMPs and BMP antagonists. During fracture healing, BMP-2, -4 and -7 were up-regulated, but BMPR-1A and BMPR-2 showed reduced expression after day 14. Among BMP antagonists, the expressions of PRDC, SOST, Smad7, GREM1 and CERBERUS were generally down-regulated during fracture healing. In contrast, Noggin was significantly up-regulated in the first week after fracture; 7 days after fracture, other BMP antagonists, including DAN, CHRD, Smad6 and BAMBI, also showed significantly increased expression. In conclusion, this study indicates that BMP antagonists can be divided into two functional groups in relation to fracture healing: (1) those whose suppression may be essential for the initiation of osteogenesis; (2) those that are upregulated and may function in the remodeling of newly formed bone.

The surgical treatment of acetabular fractures.

The goals of treating an acetabular fracture are to restore the congruity and stability of the hip joint. Some fracture types may not require surgery for a satisfactory outcome, but a displaced fracture in the weight-bearing area of the acetabulum generally should be treated with open reduction and internal fixation. The surgery is complex and demanding, and the fracture reduction must be anatomic to obtain the best result. There is no doubt, however, that an experienced surgeon can achieve an excellent result. Usually a poor result is related to residual fracture displacement or a perioperative complication. The evaluation and treatment protocols initially developed by Letournel and Judet continue to be important; in addition, the surgeon should be aware of the progress made during the past decade.

Which Anterior Acetabular Fracture Surgical Approach is Preferred? A Survey of the Orthopaedic Trauma Association Active Membership.

OBJECTIVE: The goal of this survey was to determine the current surgeon-preferred anterior surgical approach for the treatment of acetabular fractures in North America. DESIGN: Web-based survey; PARTICIPANTS:: Orthopaedic Trauma Association (OTA) members. METHODS: Active members of the OTA were solicited to participate in an OTA-sponsored survey asking for their preferred standard anterior surgical approach to the acetabulum, along with some general demographic data. The approach choices were: the classic ilioinguinal as described by Letournel, a modified ilioinguinal, the modified Stoppa (Anterior Intrapelvic) with or without a lateral window, the pararectus, and an alternative to be specified by the survey taker. RESULTS: Of the 675 total active OTA membership, 214 (32%) satisfactorily completed the survey. Of the 214 active members, only 32 (15%) prefer the classic ilioinguinal approach and 60 (28%) prefer some type of modified ilioinguinal approach. More than half of the active member respondents (121; 56.5%) prefer the modified Stoppa approach. Statistical analysis of the respondents' demographic data revealed only years in practice to be significantly different among treatment options (P < 0.01) with those with the least time in practice preferring the modified Stoppa. CONCLUSIONS: It seems that the modified Stoppa has become the preferred anterior acetabular fracture surgical approach in North America, being especially favored by those more recently in practice. The exact reasons for this change cannot be determined from this survey and are most likely multifactorial. However, training experience may play an important role.

Venous thromboembolism after hospital discharge in pelvic and acetabular fracture patients treated operatively.

PURPOSE: The purposes of this study were to determine the rate of venous thromboembolism (VTE) after discharge from the hospital in patients treated operatively with a pelvic ring or acetabular fracture and to define the main time frame in which VTE occurs within the 90-day period after hospital discharge. METHODS: California and Florida State Inpatient Databases from 2005 to 2009 were used to identify patients with clinically significant VTEs within 90 days of hospital discharge. ICD-9 diagnosis codes identified patients with a pelvic ring or acetabular fracture and a VTE. Procedure codes distinguished patients having surgical fracture treatment. Deep vein thrombosis (DVT) and pulmonary embolus (PE) were included. RESULTS: Overall, 13,589 patients had a pelvic ring or acetabular fracture and operative treatment. One hundred thirteen patients (0.83%) had a VTE within 90 days after hospital discharge: 69 (0.51%) had a DVT, 28 (0.21%) had a PE, and 16 (0.12%) had both. Twenty-four (28%) of DVTs and 10 (23%) of PEs occurred >35 days after discharge, being evenly distributed out to 90 days. There were five fatal PEs, occurring 2, 3, 7, 31, and 51 days after discharge. Therefore, overall, <0.2% of patients developed a DVT and <0.1% were diagnosed with a PE (only 1 fatal; <0.01%) >35 days after the index hospitalization. CONCLUSIONS: A substantial proportion of VTE events occur over 35 days after discharge; however, the overall risk is low with fatal PE being extremely low (<0.01%). Given the diminished VTE risk after 35 days, the decision to further extend antithrombotic drug therapy may be guided by patient-specific factors, such as prolonged immobility.

Current Trends in the Surgical Treatment of Open-Book Pelvic Ring Injuries: An International Survey Among Experienced Trauma Surgeons.

INTRODUCTION: In the open-book, rotationally unstable (OTA/AO type 61-B1.1) pelvic ring injury, the posterior sacroiliac complex is believed to remain intact. Therefore, anterior ring stabilization alone has been the standard treatment recommendation. However, treatment failures using this method have caused a reconsideration of this management strategy. Anterior plus posterior fixation is the main alternative. In the absence of any specific new guidelines, the choice of treatment currently relies on the preference of the treating surgeon. The objective of this survey was to determine the relative use of anterior plus posterior fixation, as opposed to the standard anterior fixation alone, for the treatment of open-book pelvic ring injuries. METHODS: An international group of 176 practicing trauma surgeons experienced in pelvic ring fracture fixation participated in an AO Foundation survey asking for their preferred standard surgical fixation (anterior alone or anterior plus posterior combined) for OTA/AO type 61-B1.1 open-book pelvic fractures. RESULTS: Anterior plate fixation alone (group 1) was preferred by 56% of the survey participants, and combined anterior plus posterior fixation (group 2) was preferred by 44%. Statistical analysis revealed that group 1 participants were significantly older than group 2 participants (P = 0.03) and had more years of surgical experience (P = 0.02). CONCLUSIONS: Concern regarding the inadequacy of anterior fixation alone has led many surgeons, especially those more recently in practice, to add posterior fixation, despite limited data to determine its indications. No doubt the OTA/AO type B 1.1 pelvic ring disruption actually represents a wide spectrum of injury. Further study is needed to determine the best fixation method.

Biomechanical comparison of a 2 and 3 proximal screw-configured antegrade piriformis intramedullary nail with a trochanteric reconstruction nail in an unstable subtrochanteric fracture model.

OBJECTIVE: The objective of this study was to test the stiffness and ultimate load to failure of new intramedullary (IM) nail proximal screw configurations as compared to a trochanteric reconstruction nail. METHODS: Twenty-one synthetic composite femurs were mounted on a Material Testing System and tested in axial compression 5 times. The femurs had an 1 of 2 IM nail types inserted with 1 of 3 proximal screw configurations: a 3-screw configuration with 2 transverse screws and a screw angled into the femoral neck; a 2-screw design with a single transverse screw and a single screw angled into the femoral neck; 2 parallel screws angled into the femoral neck. There were 7 specimens in each group. An unstable fracture (OTA/AO 32-C3.2) was created. and the stiffness of these constructs was tested in compression 5 times. Each construct was then loaded to failure in compression. RESULTS: The 3-screw construct provided more axial stiffness (214 N/mm +/- 75) than either the 2-screw construct (123 N/mm +/- 32) or the trochanteric reconstruction nail (127 N/mm +/- 21) (P = 0.017 and 0.035 for 3-screw vs. 2-screw and recon respectively, P = 0.45 for 2-screw vs. recon). Load-to-failure testing demonstrated similarity among the different screw configurations (3-screw = 2230 N +/- 265, 2-screw = 2283 N +/- 260, Reconstruction nail = 2121 N +/- 156) (P = 1.0 all groups). CONCLUSIONS: The proximal 3-screw configuration provided more stiffness than either the 2-screw configuration or trochanteric reconstruction nail. The 2-screw configuration performed equally to a standard trochanteric reconstruction nail in stiffness testing. The ultimate loads to failure for the 3 tested constructs were not significantly different.

Does Posterior Fixation of Partially Unstable Open-Book Pelvic Ring Injuries Decrease Symphyseal Plate Failure? A Biomechanical Study.

OBJECTIVE: Recent clinical study suggests an advantage to adding an iliosacral screw to the anterior fixation construct for anteroposterior compression type-2 (OTA/AO type 61-B1), partially unstable open-book pelvic ring injuries. Others have described stress examination to determine any required supplemental fixation. However, biomechanical studies investigating iliosacral fixation requirements for this injury are lacking. Our objective was to determine whether adding an iliosacral screw to symphyseal plate fixation decreases displacement in a well-defined open-book pelvic ring injury model. METHODS: An open-book pelvic ring injury was created in 10 human cadaveric pelves by unilaterally releasing the sacrospinous, sacrotuberous, and anterior sacroiliac ligaments plus transection of the pubic symphysis, approximating the classically described anteroposterior compression type-2 (APC-2) injury. Specimens were divided into 2 groups: (1) symphyseal plating and (2) plating plus an iliosacral screw. Using a standard bilateral stance model loaded at 550 N, displacement measurements were obtained at 210,000 and 500,000 cycles. RESULTS: Three specimens failed before 210,000 cycles because of technical errors and were excluded from analysis. For the remaining 7, there was no significant difference in displacement between the 2 groups, and none sustained implant failure. Post hoc analysis showed that a large sample size (45/group) would be required to detect any difference with 80% power, indicating a small effect size with limited clinical application. CONCLUSIONS: Adding an iliosacral screw to the symphyseal plate fixation does not provide improved biomechanical outcome in classically described APC-2 injuries. Clinically, stress examination may be useful to determine the need for supplemental posterior fixation in APC-2 injuries.

Outcomes of posterior wall fractures of the acetabulum.

BACKGROUND: The Musculoskeletal Function Assessment (MFA) is a validated, reliable, self-administered questionnaire that is useful for determining functional status. The Merle d'Aubigné score is a clinical measure of hip function. The purpose of the present study was to evaluate the outcome information provided by these two instruments after operative treatment of elementary posterior wall fractures of the acetabulum. METHODS: Forty-six patients who had been followed for a minimum of two years after operative treatment of an elementary posterior wall fracture of the acetabulum were included in the study. Functional outcomes were assessed with use of the ten individual indices and total score of the MFA, and clinical outcomes were evaluated with use of the Merle d'Aubigné score. The MFA scores were compared with previously reported normative values and with previously reported values for similar patients with hip injuries. The duration of follow-up ranged from two to fourteen years (mean, five years). RESULTS: The mean Merle d'Aubigné score was 17 (standard deviation, 1; range, 14 to 18), indicating overall good-to-excellent clinical results. However, the mean total MFA score was 23.17, which was significantly worse than the normative mean of 9.26 (p < 0.001). All MFA indices except hand/fine motor were similarly significantly worse than expected norms. The mean MFA total score was statistically similar to that reported by others for patients with hip injuries. The emotional category of the MFA score was found to be an important determinant of the total score. The Spearman rho correlation coefficient between the Merle d'Aubigné score and the MFA score was -0.62 (p < 0.001). However, the Merle d'Aubigné score data were asymmetric, demonstrating a ceiling effect (crowding of the scores at the upper end of the scale, limiting the ability of the score to demonstrate differences between patients with supposedly better clinical outcomes). CONCLUSIONS: The total MFA scores for patients with a posterior wall fracture of the acetabulum were significantly worse than normative reference values. Thus, complete recovery after a posterior wall fracture of the acetabulum is uncommon, with residual functional deficits involving wide-ranging aspects of everyday living that do not necessarily have an obvious direct connection to hip function. Although the modified Merle d'Aubigné score may be useful for evaluating isolated hip function in patients who have been treated for an acetabular fracture, its shortcomings limit its usefulness as a method for evaluating functional outcome in these patients. Research efforts should be directed toward the identification of the psychosocial and other underlying determinants of functional outcome and potential related treatment interventions.