Tibial Plateau Fractures: Addressing Commonly Encountered Challenges in Reduction and Fixation.

Tibial plateau fractures encompass a broad array of injuries. The mechanism of injury ranges from low to high energy. Devastating complications and associated injuries can occur in both low-energy and high-energy mechanisms; therefore, a careful and detailed physical examination and review of imaging must be performed. Furthermore, a mechanistic approach to fracture classification and morphology enhances the surgeon's understanding of the injury and the ability to predict associated injuries and develop effective strategies for management.

The diagnostic accuracy of MRI for evaluating the posterolateral corner in acute knee dislocation.

OBJECTIVE: To investigate the diagnostic performance of preoperative MRI in evaluating posterolateral corner (PLC) structures after acute knee dislocation (KD) and determine the correlation of MRI with operative findings for grading structure integrity. METHODS: Acute knee (femorotibial) dislocations between 2005 and 2020 with preoperative MRI and surgical posterolateral corner repair were identified from a single academic institution. From MRI, integrity was evaluated for PLC structures: lateral collateral ligament (LCL), popliteus tendon (PT), biceps femoris tendon (BFT), and ligamento-capsular complex (LCC). Frequency of injury to each structure and number of PLC structures torn in each case were tabulated. Diagnostic performance of MRI was determined using surgery as the reference standard. Correlation between MRI and surgery for each PLC structure was determined using kappa. RESULTS: Thirty-nine KD cases (19 right) in 39 patients (28 male) were included, with mean age of 33 years. Mechanism of injury was as follows: high energy 52%, low energy 38%, ultra-low energy 10%. LCL was most frequently torn, in 95% (37/39) of cases. Most commonly, three of four PLC structures were torn in 54% (21/39) of cases. Diagnostic accuracy of MRI was high for LCL 95%, BFT 87%, PT 82%, and LCC 92%. Correlation between MRI and surgical findings was variable: substantial for BFT, moderate for LCL and PT, and fair for LCC. CONCLUSION: MRI has high accuracy for detecting tears of posterolateral corner stabilizers in the setting of acute KD. However, for grading structure integrity, the correlation of MRI with surgical findings is variable, ranging from fair to substantial. KEY POINTS: • In acute knee dislocation, MRI has high diagnostic accuracy for detecting tears of posterolateral corner (PLC) structures. • Preoperative MRI should be considered by orthopedic surgeons when there is clinical concern for posterolateral corner instability following acute knee dislocation. • Although MRI is valuable in the preoperative investigation of knee dislocation, clinical assessment and intraoperative exploration may still be required for definitive diagnosis.

Comparing the rates and modes of failure of two third generation cephalomedullary nail systems in the treatment of intertrochanteric hip fractures.

INTRODUCTION: Cephalomedullary (CMN) implants are commonly used to address elderly intertrochanteric hip fractures. Multiple CMN implant systems exist with subtle variation between manufacturers. Multiple modes of CMN failure have been described in the literature. The present study assessed the local modes and rates of construct failure (nail fracture, cut-out and non-union) of two such implants, after a change in implant supply provided the opportunity for retrospective comparison. Additional investigation was undertaken to assess whether any predictors of failure could be identified based on common radiographic measurement parameters. METHODS: Based on local implant records, all consecutive patients who suffered an intertrochanteric fracture, treated at a tertiary care hospital with a cephalomedullary nail from January 2014 to January 2018 were included. Patients were excluded if they received a CMN for pathologic fracture. Within the collection period all patients received either a Synthes Trochanteric Fixation Nail (TFN) or Zimmer Natural Nail (ZNN). Patients were retrospectively assessed for fracture reduction and implant technique parameters at the time of initial surgery. Radiographic data were assessed at minimum two years post-operatively to assess for union. Patient demographic data was followed to assess rate and mode of failure. RESULTS: Six hundred and sixty-two patients were included in the study, from which a propensity matched cohort was derived. Comparing across equivalent cohorts, no differences in the rate or mode of construct failure were identified between the TFN and ZNN. When assessing the entire cohort we observed 39 construct failures (5.9%), which included 31 instances of nail cutout (4.7%), 4 episodes of nail fracture (0.6%) and 4 failures related to non-union (0.6%). Tip to apex distance, sagittal malalignment and Cleveland zone were identified as significant predictors of nail failure. CONCLUSION: No difference in rates or modes of failure were identified between the TFN and ZNN constructs. Similar to previous reports we again identified the impact of tip to apex distance on construct failure and further identified Cleveland zone and sagittal malalignment as significant risks for failure.

Outcome After Open Reduction Internal Fixation of Acetabular Fractures in the Elderly.

OBJECTIVES: (1) Assess outcomes of acetabular open reduction and internal fixation (ORIF) in the elderly, (2) investigate factors influencing outcome, and (3) compare outcomes after low-energy and high-energy mechanisms of injury. DESIGN: Retrospective case series. SETTING: Level 1 trauma center. PATIENTS: Seventy-eight patients older than 60 years (age: 70.1 ± 7.4; 73.1% males). INTERVENTION: ORIF for acetabular fractures. MAIN OUTCOME MEASUREMENTS: Complications, reoperation rates, Oxford Hip Score (OHS), and joint preservation and development of symptomatic osteoarthritis. Cases with osteoarthritis, OHS < 34, and those who required subsequent total hip arthroplasty were considered as poor outcome. RESULTS: At a mean follow-up of 4.3 ± 3.7 years, 11 cases post-ORIF required a total hip arthroplasty. The 7-year joint survival post-ORIF was 80.7 ± 5.7%. Considering poor outcome as failure, the 7-year joint survival was 67.0 ± 8.9%. The grade of reduction was the most significant factor associated with outcome post-ORIF. Female sex (P = 0.03), pre-existing osteoporosis (P = 0.03), low-energy trauma (P = 0.04), and Matta grade (P = 0.002) were associated with poor outcome. Patients with associated both-column fractures were more likely to have nonanatomic reduction (P = 0.008). After low-energy trauma, joint survivorship was 36.6 ± 13.5% at 7 years compared with 75.4 ± 7.4% in the high-energy group when considering poor outcome as an end point (log rank P = 0.006). The cohort's mean OHS was 37.9 ± 9.3 (17-48). CONCLUSIONS: We recommend ORIF whenever an anatomic reduction is feasible. However, achievement and maintenance of anatomic reduction are a challenge in the elderly, specifically in those with low-energy fractures involving both columns, prompting consideration for alternative management strategies. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Urinary catheter use in patients with hip fracture: Are current guidelines appropriate? A retrospective review.

BACKGROUND: Guidelines for urinary catheterization in patients with hip fracture recommend limiting catheter use and using intermittent catheterization preferentially to avoid complications such as urinary tract infection (UTI) and postoperative urinary retention (POUR). We aimed to compare current practices to clinical guidelines, describe the incidence of POUR and UTI, and determine factors that increase the risk of these complications. METHODS: We retrospectively reviewed the charts of patients with hip fracture who presented to a single large tertiary care centre in southeastern Ontario between November 2015 and October 2017. Data collected included comorbidities, catheter use and length of stay. We compared catheter use to guidelines, and investigated the incidence of and risk factors for POUR and UTI. RESULTS: We reviewed the charts of 583 patients, of whom 450 (77.2%) were treated with a catheter, primarily indwelling (416 [92.4%]). Postoperative urinary retention developed in 98 patients (16.8%); however, it did not affect length of stay (p = 0.2). Patients with indwelling catheters for more than 24 hours after surgery had a higher incidence of POUR than those who had their catheter removed before 24 hours (65/330 [19.7%] v. 10/98 [10.2%]) (odds ratio [OR] 2.2, 95% confidence interval [CI] 1.06-4.38). A UTI developed postoperatively in 62 patients (10.6%). Catheter use was associated with a 6.6-fold increased risk of UTI (OR 6.6, 95% CI 2.03-21.4). Patients with indwelling catheters did not have a significantly higher incidence of UTI than those with intermittent catheterization (57/416 [13.7%] v. 2/34 [5.9%]) (p = 0.2). Patients who developed a UTI had significantly longer catheter use than patients who did not (p < 0.002). CONCLUSION: Indwelling catheters were used frequently, which suggests low compliance with clinical guidelines. Longer duration of catheter use led to higher rates of UTI and POUR. Further investigation of the reasons for the common use of indwelling rather than intermittent catheterization is needed.

Patellar Fractures: Anatomy, Mechanics, and Surgical Management.

➤: A preoperative computed tomography scan may be considered to improve surgical planning, as secondary fracture lines are poorly visualized on radiographs. ➤: Oblique internal and external rotation fluoroscopic views may be used intraoperatively to fully evaluate the medial and lateral facet articular reduction if direct assessment by visualization or palpation is not completed. ➤: Partial patellectomy for inferior pole fractures should be avoided, and bone-preserving procedures are recommended. ➤: A lateral arthrotomy may be used for direct visualization of the articular reduction for multifragmentary fractures. An inferomedial arthrotomy should be avoided to protect the dominant blood supply of the patella. ➤: Tension band fixation with cannulated screws yields a lower reoperation rate, improved functional outcome scores, and better performance in biomechanical studies than Kirschner wire-based tension band fixation. ➤: Preliminary studies of novel plate and screw constructs for osteosynthesis have shown promising results.

Preventing hip fractures with multidisciplinary teams: a Canadian perspective.

Fragility fractures (FFs) are low-energy trauma fractures that occur at or below standing height. Among FFs, hip fractures are associated with the greatest morbidity, mortality and cost to Canadian health care systems. This review highlights the current state of medical care for hip fractures in Canada, with specific focus on the role of the multidisciplinary team. Gaps in care exist, as FFs represent a unique challenge requiring both acute and chronic management. Furthermore, there is a lack of ownership of FFs by a medical specialty. These gaps can be addressed through the use of multidisciplinary teams, which have been shown to be efficacious and cost-effective. This model of care also addresses numerous patient-identified barriers to treatment, including inadequate patient counselling. However, there is still room for improvement in both the identification of patients at risk for hip fracture and patient adherence to therapy.

Les fractures de fragilisation (FF) sont des fractures qui surviennent lors d'un traumatisme léger se produisant depuis la position debout ou d'une hauteur moindre. Les fractures de la hanche sont les FF associées aux plus grands taux de morbidité et de mortalité et aux plus grands coûts pour les systèmes de santé au Canada. La présente revue s'intéresse à l'état actuel des soins médicaux pour une fracture de la hanche au pays et porte une attention spéciale au rôle de l'équipe multidisciplinaire. Des lacunes dans les soins existent et sont mises en évidence par les FF, qui posent un défi bien particulier en nécessitant une prise en charge à la fois aiguë et chronique. De plus, cette prise en charge ne relève d'aucune spécialité médicale. La correction de ces lacunes peut passer par le recours aux équipes multidisciplinaires, dont l'efficacité et la rentabilité ont été démontrées. Ce modèle de soins élimine également de nombreux obstacles au traitement signalés par les patients, y compris le counseling inadéquat. Des améliorations sont néanmoins encore nécessaires dans l'identification des patients à risque de fracture de la hanche et dans l'observance du traitement.

Does use of a quadrilateral surface plate improve outcome in elderly acetabular fractures?

BACKGROUND: Acetabular fractures in the elderly frequently involve segmental quadrilateral plate injury, yet no consensus exists on how to best control the femoral head medial displacement. Quadrilateral surface plates (QSP) were developed to help buttress these challenging fractures. The study aims to 1) Determine the prevalence of segmental quadrilateral plate fractures (SQPF) in elderly patients; and 2) Assess if utilization of a QSP is associated with improved acetabulum fracture reduction and outcome. METHODS: This was a retrospective study conducted at a level-1 trauma centre. . All patients over 60-years that sustained an acetabular fracture between 2007 and 2019 were reviewed. Pre-operative pelvic radiographs and CT imaging were reviewed for 96 patients, to assess for SQPF. From the 96 patients reviewed, over one third of patients (n = 40, 41.6%) sustained a SQPF. Patients that had an acute-THA (n = 7) were excluded as were patients that underwent an ORIF but did not have a QSP or an anterior column buttress plate (n = 3). The remaining 30 formed the study's cohort. We assessed the ability to achieve and maintain reduction in this elderly population, and compared outcomes using traditional anterior column buttress plates (ilioingual or intra-pelvic approach) versus an intra-pelvic pre-contoured buttress suprapectineal plate (QSP). Outcome measures included: fracture reduction using the Matta classification (desirable: anatomical/imperfect and poor), re-operations, conversion to THA and Oxford Hip Score (OHS) (for the preserved hips). RESULTS: Ten patients had an ORIF with utilization of a QSP (QSP-group), and 20 had an ORIF but did not have the QSP (non-QSP-group). There was no difference in patient demographics between groups. Fracture patterns were also similar (p = 0.6). Postoperative fracture reduction was desirable (anatomical/imperfect) in 17 patients and poor in 13. Improved ability to achieve a desirable reduction was seen in the QSP-group (p = 0.02). Conversion to THA was significantly lower in patients that had a desirable fracture reduction (appropriate: 3/17; poor: 7/13). No patients in the QSP-group have required a THA to-date, compared to 10/20 patients in the non-QSP-group (p = 0.01). The mean time to THA was 1.6 ± 2.1 year. There was no difference in OHS between the two groups (34.4 ± 10.3). CONCLUSION: Elderly acetabulum fractures have a high incidence (approaching 40%) of segmental QPF. Desirable (anatomical/imperfect) fracture reduction was associated with improved outcome. The use of a QSP was associated with improved ability to achieve an appropriate reduction. A QSP should be considered as they are both reliable and reproducible with a significantly improved fracture reduction and lower conversion to THA.

Short Versus Long InterTAN Fixation for Geriatric Intertrochanteric Hip Fractures: A Multicentre Head-to-Head Comparison.

OBJECTIVE: To determine if geriatric intertrochanteric hip fracture patients achieve equivalent postoperative functional status after management with either a short (180-200 mm) or a long (260-460 mm) InterTAN intramedullary device. DESIGN: Retrospective review of a prospective randomized control trial. SETTING: Four Level I Trauma Centers. PATIENTS/PARTICIPANTS: One hundred eight patients with OTA/AO classification 31A-1 and 31A-2 intertrochanteric hip fractures were included in the study. INTERVENTION: Internal fixation using an IT device. MAIN OUTCOMES MEASURES: Primary outcomes included Functional Independence Measure and Timed Up and Go. Secondary outcomes included blood loss, surgical time, length of stay, adverse events, and mortality. RESULTS: Seventy-one short and 37 long IT patients met study inclusion criteria. Demographics were similar between groups. There was no difference in Functional Independence Measure or Timed Up and Go scores between the 2 IT groups at any of the time points collected. Mean operative time was lower in the short IT group than in the long IT group (60 vs. 73 minutes; P = 0.021). A higher proportion of long IT patients had reamed constructs (95% vs. 48% short IT, P < 0.001). Postoperative blood loss was significantly higher in the long IT group without a significant influence on the number of patients requiring transfusion (P = 0.582) or average units transfused (P = 0.982). There was no significant difference in the proportion of postoperative adverse events between the 2 cohorts despite a higher number of peri-implant femur fractures in the short IT group than in the long IT group (5 vs. 1, P = 0.350). CONCLUSIONS: Postoperative functional status was not influenced by the length of IT device in the management of geriatric intertrochanteric hip fractures. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Open reduction internal fixation vs non-operative management in proximal humerus fractures: a prospective, randomized controlled trial protocol.

BACKGROUND: Proximal humerus fractures are the third most common fracture in the elderly population and are expected to increase due to the aging population. Surgical fixation with locking plate technology has increased over the last decade despite a lack of proven superiority in the literature. Three previous randomized controlled trials have not shown a difference in patient-centered outcomes when comparing non-operative treatment with open reduction and internal fixation. Low patient enrollment and other methodological concerns however limit the generalizability of these conclusions and as a result, management of these fractures remains a controversy. By comparing the functional outcomes of locked plate surgical fixation versus non-operative treatment of displaced three and four-part proximal humerus fractures in the elderly population with a large scale, prospective, multi-centered randomized controlled trial, the optimal management strategy for this common injury may be determined. METHODS: We will conduct a prospective, single blind randomized controlled parallel arm trial to compare non-operative management of proximal humerus fractures with open reduction and internal fixation using locked plating technology. One-hundred and sixty patients > age 60 with acute 3- or 4- part proximal humerus fractures will be randomized to either open reduction and internal fixation with locked plating technology or non-operative management treatment arms. The primary outcome measure is the Constant Score at 24 months post-operative. Secondary outcome measures include the American Shoulder and Elbow Surgeon's Score (ASES), EuroQol EQ-5D-5 L Health Questionnaire Score, short form PROMIS upper extremity score and IPAQ for the elderly score. Further outcome measures include assessment of the initial classification, displacement and angulation and the quality of surgical reduction via a standard computed tomography (CT) scan; rates of non-union, malunion, arthrosis, osteopenia or other complications including infection, nerve injury, intra-articular screw penetration, reoperation rates and hospital re-admission rates. DISCUSSION: The results of this trial will provide Level 1 evidence to guide decision-making in the treatment of proximal humerus fractures in the elderly population. TRIAL REGISTRATION: ClinicalTrials.gov NCT02362100 . Registered 5 Feb 2015.

The Effect of Varying Tension of a Suture Button Construct in Fixation of the Tibiofibular Syndesmosis-Evaluation Using Stress Computed Tomography.

BACKGROUND/PURPOSE: There have been no studies assessing the optimal biomechanical tension of suture button constructs. The purpose of this study was to assess optimal tensioning of suture button fixation and its ability to maintain reduction under loaded conditions using a stress computed tomography (CT) model. METHODS: Ten cadaveric lower limbs disarticulated at the knee were used. The limbs were placed in a modified ankle load frame that allowed for the application of sustained torsional axial or combined torsional/axial loads. The syndesmosis and the deep deltoid ligaments complex were sectioned and the limbs were randomized to receive a suture button construct tightened at 4, 8, or 12 kg. The specimens were loaded under the 3 loading scenarios with CT scans performed after each and at the conclusion of testing. Multiple measurements of translation and rotation were compared with baseline CT scan taken before sectioning. RESULTS: Significant lateral (maximum 5.26 mm) and posterior translation (maximum 6.42 mm) and external rotation (maximum 11.71 degrees) was noted with the 4 kg repair. Significant translation was also seen with both the 8 and the 12 kg repairs; however, the incidence was less than with the 4 kg repair. Significant overcompression (ML = 1.69 mm, B = 2.69 mm) was noted with the 12 kg repair and also with the 8 kg repair (B = 2.01 mm). CONCLUSION: Suture button constructs must be appropriately tensioned to maintain reduction and re-approximate the degree of physiological motion at the distal tibiofibular joint. These constructs also demonstrate overcompression of the syndesmosis; however, the clinical effect of this remains to be determined.

A Multicenter Randomized Control Trial Comparing a Novel Intramedullary Device (InterTAN) Versus Conventional Treatment (Sliding Hip Screw) of Geriatric Hip Fractures.

OBJECTIVES: To compare outcomes in elderly patients with intertrochanteric hip fractures treated with either the sliding hip screw (SHS) or InterTAN intramedullary device (IT). DESIGN: Prospective, randomized, multicenter clinical trial. SETTING: Five level 1 trauma centers. PATIENTS: Two hundred forty-nine patients 55 years of age or older with AO/OTA 31A1 (43) and OA/OTA 31A2 (206) fractures were prospectively enrolled and followed for 12 months. INTERVENTION: Computer generated randomization to either IT (n = 123) or SHS (n = 126). MAIN OUTCOME MEASUREMENTS: The Functional Independence Measure (FIM) and the Timed Up and Go test (TUG) were used to measure function and motor performance. Secondary outcome measures included femoral shortening, complications, and mortality. RESULTS: Demographics, comorbidities, preinjury FIM scores and TUG scores were similar between groups. Patients (17.2%) who received an IT had limb shortening greater than 2 cm compared with 42.9% who received an SHS (P < 0.001). To determine the importance of preinjury function and fracture stability, we analyzed the subgroup of patients with the ability to walk 150 m independently preinjury and an OA/OTA 31A-2 fracture (n = 70). In this subgroup, patients treated with SHS had greater shortening and demonstrated poorer FIM and TUG scores compared with patients treated with an IT. CONCLUSIONS: Overall, most patients with intertrochanteric femur fractures can expect similar functional results whether treated with an intramedullary or extramedullary device. However, active, functional patients have an improved outcome when the InterTAN is used to treat their unstable intertrochanteric fracture. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Acetabular fractures in the elderly: evaluation and management.

Acetabular fracture patterns in the elderly, with increased involvement of the anterior column, quadrilateral plate comminution, medialization of the femoral head, and marginal impaction, differ from those noted among a younger cohort. Poor prognostic factors for open reduction and internal fixation (ORIF) are posterior wall comminution, marginal impaction of the acetabulum, a femoral head impaction fracture, a so-called gull sign, and hip dislocation. The rate of conversion to total hip arthroplasty following formal ORIF has been reported to be 22% at a mean of twenty-nine months. Total hip replacement after an acetabular fracture generally yields good clinical results; however, in the acute setting, it must be combined with proper stable fracture fixation.

Negative-pressure wound therapy after fasciotomy reduces muscle-fiber regeneration in a pig model.

BACKGROUND: Negative-pressure wound therapy (NPWT) can improve fasciotomy wound closure, but its effects on skeletal muscle are largely unknown. The purpose of this study was to evaluate NPWT effects on skeletal muscle after fasciotomy for compartment syndrome in an animal model and to assess regional variability in muscle fiber regeneration. METHODS: Compartment syndrome was induced in the hindlimb of twenty-two adult female pigs with use of a continuous intracompartmental serum-infusion model. Fasciotomy was performed after six hours, and animals were randomized to receive either wet-to-dry gauze dressings (control group) or NPWT dressings (-125 mm Hg, continuous suction) for seven days. Delayed primary wound closure was attempted at seven days, and the peroneus tertius was harvested for analysis seven days or twenty-one days after fasciotomy. Muscles were weighed, and hematoxylin and eosin-stained samples from four regions of the muscle (superficial central, deep central, lateral, and proximal) were mapped for different cellular morphologies. RESULTS: Muscle weight was greater in the affected limb at all time points with no difference between treatment groups. At seven days, only the deep central samples in the NPWT group had a significantly greater cross-sectional area containing normal fibers as compared with that found in the controls. By twenty-one days, the deep central, lateral, and proximal regions of the NPWT-treated muscles had a smaller cross-sectional area containing normal fiber morphology and a greater cross-sectional area containing only mononucleated cells as compared with the controls. CONCLUSIONS: NPWT did not decrease muscle weight. At twenty-one days, the extent of muscle fiber regeneration after fasciotomy for compartment syndrome was reduced in muscles treated with NPWT for seven days compared with the values in the control group treated with wet-to-dry gauze dressings. CLINICAL RELEVANCE: NPWT may be harmful to skeletal muscle after compartment syndrome requiring fasciotomy and local wound care.

APTF: anteroposterior tibiofibular ratio, a new reliable measure to assess syndesmotic reduction.

OBJECTIVES: To assess the accuracy of a new radiographic measurement of the distal tibia and fibula on the lateral view of the ankle in normal adults: the anteroposterior tibiofibular (APTF) ratio. METHOD: Thirty adults without history of trauma or disease of the ankle were included. Bilateral ankles were x-rayed with a true lateral view of the ankle. A line from the anterior tibial physis scar to the posterior tibial cortex, passing by the intersection of the physis and the fibula anterior cortex, was drawn. The APTF ratio was calculated as the ratio of the anterior segment to the posterior segment. The measurements were done by 3 independent evaluators. Intra- and interobserver reliability was obtained using intraclass correlation. RESULTS: The APTF ratio was 0.94 ± 0.13 with a range of 0.63-1.31. Sex and age had no effect on the results. Inter- and intraobserver reliability was good to very good with an intraclass correlation between 0.6 and 0.8. A strong correlation between the left and the right APTF ratio was observed (r = 0.501 and P = 0.001). CONCLUSION: The distal tibiofibular joint anatomy in the sagittal plane can be accurately assessed with a new reliable radiographic measurement, the APTF ratio. The reduction of this joint during surgery can be confirmed with a true lateral view of the ankle. The anterior fibula cortex crosses the tibial physeal scar at the center of the line crossing this point and the anterior cortex of the tibia at the level of the physeal scar in the normal ankle.

Distal radius fractures: nonoperative and percutaneous pinning treatment options.

Nonoperative treatment of distal radial fractures by reduction and immobilization remains the most common treatment, based on the incidence of appropriate fracture types, as seen in many epidemiological studies in the literature. In this article, the indications, technique, predictors of failure, outcomes, and complications are reviewed. A variety of treatment options have been proposed for distal radial fractures that are predicted, or subsequently identified, to be too unstable for nonoperative management. Percutaneous pinning is an effective option for select fractures. The authors also review the indications, described techniques, complications and outcomes associated with this treatment option.

Distal radius fractures: nonoperative and percutaneous pinning treatment options.

Nonoperative treatment of distal radial fractures by reduction and immobilization remains the most common treatment, based on the incidence of appropriate fracture types, as seen in many epidemiological studies in the literature. In this article, the indications, technique, predictors of failure, outcomes, and complications are reviewed. A variety of treatment options have been proposed for distal radial fractures that are predicted, or subsequently identified, to be too unstable for nonoperative management. Percutaneous pinning is an effective option for select fractures. The authors also review the indications, described techniques, complications and outcomes associated with this treatment option.

The influence of implant articular thickness and glenohumeral conformity on stability of an all-metal glenoid component.

The objective of this study was to determine the effect of implant thickness and glenohumeral conformity on fixation of an all-metal glenoid component. A stainless steel glenoid component was designed and implanted in 10 cadaveric scapulae. A testing apparatus capable of producing a loading vector at various angles, magnitudes, and directions was used. The independent variables included 6 directions and 3 angles of joint load, 3 implant thicknesses, and 4 glenohumeral conformities. Implant micromotion relative to bone was measured by use of 4 displacement transducers at the superior, inferior, anterior, and posterior sites. The components displayed a consistent response to loading of ipsilateral compression and contralateral distraction. Stability decreased as the load application angle increased (P < .05). A decrease in the implant thickness and glenohumeral conformity resulted in increased implant stability (P < .05). Decreasing implant thickness and glenohumeral conformity reduce the eccentric component of loading and may improve the durability of glenoid implants.

An in vivo rabbit model for cartilage trauma: a preliminary study of the influence of impact stress magnitude on chondrocyte death and matrix damage.

OBJECTIVE: This study was designed to evaluate the postimpact response of the articular cartilage in the rabbit knee after a single traumatic episode. DESIGN: A novel servo-controlled Rabbit Impact Test System (RITS) was developed to apply a well-defined trauma to the femoral condyle in the rabbit knee. The RITS was first used in an in vitro study to determine an appropriate stress to cause cartilage damage without bone fracture. Viable rabbit knees (n = 18) were impacted with stresses of 15 to 50 MPa at a stress rate of 420 MPa/s, the latter corresponding to joint impact rates commonly seen in sports injuries and vehicular accidents. Based on the in vitro study, we performed an in vivo study by impacting the knees of rabbits (n = 9) with a 35 MPa peak stress at a stress rate of 420 MPa/s. The articular cartilage in these knees was analyzed at 0 and 3 weeks after impaction. SETTING: Center for Laboratory Animal Services, Hospital for Special Surgery. SUBJECTS: A total of 27 New Zealand White rabbits were used in this study. INTERVENTION: A rabbit's knee was rigidly immobilized in the adjustable frame of the RITS. A small incision on the knee exposed the lateral condyle and the impactor was positioned perpendicular to the surface of the condyle. The lateral femoral condyle of the left knee was impacted, whereas the right knee was sham operated and used as a control. MAIN OUTCOME MEASUREMENTS: Visual matrix damage, cell viability, and microscopic matrix damage was assessed. RESULTS: In the in vitro study, matrix damage was observed at stress magnitudes > or =30 MPa. However, cell death was initiated at approximately 20 MPa at the articular surface and increased in depth with increasing stress magnitude (2.8 +/- 2% thickness/MPa,). In the in vivo study, visible surface damage was observed immediately after impaction but not at 3 weeks after impaction. At 3 weeks, the articular cartilage showed significant arthritic changes (matrix damage, chondrocyte death, and proteoglycan loss) typical of late-stage osteoarthritis. CONCLUSIONS: Our novel impact test system was able to accurately apply a quantifiable stress magnitude at a constant stress rate to rabbit femoral condyles in the in vitro and in vivo settings. At the time of impaction, the extent of cell death depended with the intensity of trauma (stress magnitude) in which complete cell death was observed in the impacted site at >40 MPa. Under in vivo conditions, the test system was able to consistently produce superficial matrix damage and cell death at 35 MPa stress magnitude at the time of impaction. This resulted in cartilage "arthritic" changes by 3 weeks postinjury.

Does keel size, the use of screws, and the use of bone cement affect fixation of a metal glenoid implant?

The objective of this study was to determine the effect of screws and keel size on the fixation of an all-metal glenoid component. A prototype stainless-steel glenoid component was designed and implanted in 10 cadaveric scapulae. A testing apparatus capable of producing a loading vector at various angles, magnitudes, and directions was used. The independent variables included six directions and three angles of joint load, and five fixation modalities-three different-sized cross-keels (small, medium, and large), screws, and bone cement. Implant micromotion relative to bone was measured by four displacement transducers at the superior, inferior, anterior, and posterior sites. The components displayed a consistent response to loading of ipsilateral compression and contralateral distraction. Use of progressively larger keels did not significantly improve implant stability. Stability decreased as the angle of load application increased (P <.05). Screw and cement fixation resulted in the most stable fixation (P <.05).