Kenneth J. Koval

Biomechanics of locked plates and screws

Objective: To review the biomechanical principles that guide fracture fixation with plates and screws; specifically to compare and contrast the function and roles of conventional unlocked plates to locked plates in fracture fixation. We review basic plate and screw function, discuss the design rationale for the new implants, and examine the biomechanical evidence that supports the use of such implants. Data Sources: Systematic review of the per reviewed English language orthopaedic literature listed on PubMed (National Library of Medicine online service). Study Selection: Papers selected for this review were drawn from peer review orthopaedic journals. All selected papers specifically discussed plate and screw biomechanics with regard to fracture fixation. PubMed search terms were: plates and screws, biomechanics, locked plates, PC-Fix, LISS, LCP, MIPO, and fracture fixation. Data Synthesis: The following topics are discussed: plate and screw function—neutralization plates and buttress plates, bridge plates; fracture stability—specifically how this effects gap strain and fracture union, conventional plate biomechanics, and locking plate biomechanics. Conclusions: Locked plates and conventional plates rely on completely different mechanical principles to provide fracture fixation and in so doing they provide different biological environments for healing. Locked plates may increasingly be indicated for indirect fracture reduction, diaphyseal/metaphyseal fractures in osteoporotic bone, bridging severely comminuted fractures, and the plating of fractures where anatomical constraints prevent plating on the tension side of the bone. Conventional plates may continue to be the fixation method of choice for periarticular fractures which demand perfect anatomical reduction and to certain types of nonunions which require increased stability for union.

The Neer classification system for proximal humeral fractures : an assessment of interobserver reliability and intraobserver reproducibility

The radiographs of fifty fractures of the proximal part of the humerus were used to assess the interobserver reliability and intraobserver reproducibility of the Neer classification system. A trauma series consisting of scapular anteroposterior, scapular lateral, and axillary radiographs was available for each fracture. The radiographs were reviewed by an orthopaedic shoulder specialist, an orthopaedic traumatologist, a skeletal radiologist, and two orthopaedic residents, in their fifth and second years of postgraduate training. The radiographs were reviewed on two different occasions, six months apart. Interobserver reliability was assessed by comparison of the fracture classifications determined by the five observers. Intraobserver reproducibility was evaluated by comparison of the classifications determined by each observer on the first and second viewings. Kappa (kappa) reliability coefficients were used. All five observers agreed on the final classification for 32 and 30 per cent of the fractures on the first and second viewings, respectively. Paired comparisons between the five observers showed a mean reliability coefficient of 0.48 (range, 0.43 to 0.58) for the first viewing and 0.52 (range, 0.37 to 0.62) for the second viewing. The attending physicians obtained a slightly higher kappa value than the orthopaedic residents (0.52 compared with 0.48). Reproducibility ranged from 0.83 (the shoulder specialist) to 0.50 (the skeletal radiologist), with a mean of 0.66. Simplification of the Neer classification system, from sixteen categories to six more general categories based on fracture type, did not significantly improve either interobserver reliability or intraobserver reproducibility.

Operative management of displaced femoral neck fractures in elderly patients: An international survey

BACKGROUNDnHip fractures occur in 280,000 North Americans each year. Although surgeons have reached consensus with regard to the treatment of undisplaced fractures of the hip, the surgical treatment of displaced fractures remains controversial. Identifying surgeons preferences in techniques, and the rationale for their choices, may aid in focusing educational activities to the orthopaedic community as well as planning future clinical trials. Our objective was to clarify current opinion with regard to the operative treatment of displaced fractures of the femoral neck.nnnMETHODSnWe used a cross-sectional survey design and a sample-to-redundancy strategy to examine surgeons preferences in the treatment of displaced femoral neck fractures. We mailed this survey to members of the Orthopaedic Trauma Association and European-AO International-affiliated trauma centers.nnnRESULTSnOf 442 surgeons who received the questionnaire, 298 (67%) responded. The typical respondent was a North American man over the age of forty years who was in academic practice, supervised residents, had fellowship training in trauma, and worked in a low-volume center (<100 hip fractures per year), treating an equal proportion of displaced and undisplaced femoral neck fractures. Most surgeons believed that internal fixation was the procedure of choice in younger patients (those who are less than sixty years old) with a displaced fracture (Garden type III or IV). For patients over eighty years old with Garden type-III or IV fractures, almost all surgeons preferred arthroplasty. Respondents varied widely in their preferences for the treatment of patients who were sixty to eighty years old with a displaced fracture (Garden type III or IV) or active patients with a Garden type-III fracture. Many surgeons believed there was no difference between arthroplasty and internal fixation when considering mortality (45%), infection rates (30%), and quality of life (37%). Surgeons also revealed variable preferences in their choice of the optimal approach to arthroplasty for patients between sixty and eighty years old with a type-IV fracture (32% preferred unipolar; 41%, bipolar; and 17%, total hip arthroplasty) and in the optimal choice of implant for internal fixation.nnnCONCLUSIONSnWhile surgeons prefer internal fixation for younger patients and arthroplasty for older patients, they disagree about the optimal approach to the management of patients between sixty and eighty years old with a displaced fracture and active patients with a Garden type-III fracture. Surgeons also disagree on the optimal implants for internal fixation or arthroplasty.

Staged management of high-energy proximal tibia fractures (OTA types 41): the results of a prospective, standardized protocol.

Objectives: This study evaluated the use of a staged protocol involving temporary spanning external fixation and delayed formal definitive fixation in the management of high-energy proximal tibia fractures (OTA types 41) with regard to soft-tissue management, development of complications, and functional outcomes. Setting: Two level-one trauma centers and a tertiary care orthopaedic center. Patients: Fifty-three patients with 57 high-energy tibial plateau fractures. Methods: The authors instituted a protocol of immediate placement of knee spanning external fixation with management of soft-tissue injuries for all high-energy proximal tibia fractures. Between August 1999 and May 2002, 62 consecutive patients with 67 high-energy proximal tibia fractures (OTA types 41A, B, C) underwent temporary knee spanning external fixation on the day of admission. Nine patients with 10 fractures who transferred care after initial stabilization or sustained an extraarticular fracture were excluded. The remaining 53 patients with 57 fractures underwent repair of articular fractures and meta-diaphyseal fracture repair with plates and screw constructs or conversion to a ring fixator. These patients had a mean age of 47 years (standard deviation (SD), 14). Of these 53 patients, 42 (79%) were men and 11 (21%) were women. Characteristics of the 57 fractures were: 42 Schatzker VI (74%), 12 Schatzker V (21%), 2 Schatzker IV (4%), and 1 Schatzker II (2%). There were 41 closed fractures and 16 open fractures. (One patient had bilateral fractures with 1 extremity open and 1 closed). Orthopaedic evaluation at latest follow-up included a clinical and radiographic examination and functional outcome measurement with the Western Ontario McMaster functional knee score (WOMAC). Eight patients with 8 fractures were lost to follow-up. This left 45 patients with 49 fractures with a mean follow-up of 15.7 (SD, 5.7; range, 8-40) months. Results: Complications included 3 (5%) deep wound infections, 2 (4%) nonunions, and 2 patients (4%) with significant knee stiffness (<90°). Nine patients (16%) underwent additional surgery after definitive skeletal stabilization related to their injury. Range of knee motion at final follow-up was 1° (SD, 4) to 106° (SD, 15). The mean WOMAC was 91 (SD, 55). Poor results did not correlate with demographic or injury characteristics. Discussion: We had a relatively low rate of wound infection in these complex injuries (5% overall). There was only 1 wound problem in our subset of patients with closed fractures and 2 infections in those with open fractures. One downside of this technique may be residual knee stiffness. The benefits of temporizing spanning external fixation include osseous stabilization, access to soft tissues, and prevention of further articular damage. Our relatively low rates of complications in patients who sustain high-energy proximal tibia fractures and the access this technique affords in open fractures and those with compartment syndrome lead us to recommend this technique in all high-energy intra-articular and extra-articular fractures of the proximal tibia. Clinical Relevance: This study supports the practice of delayed internal fixation until the soft-tissue envelope allows for definitive fixation.

Treatment of distal tibia fractures without articular involvement : A systematic review of 1125 fractures

The management of unstable distal tibia fractures remains challenging. The mechanism of injury and the prognosis of these fractures are different from pilon fractures, but their proximity to the ankle makes the surgical treatment more complicated than the treatment tibial midshaft fractures. A variety of treatment methods have been suggested for these injuries, including nonoperative treatment, external fixation, intramedullary nailing, and plate fixation. However, each of these treatment options is associated with certain challenges. Nonoperative treatment may be complicated by loss of reduction and subsequent malunion. Similarly, external fixation of distal tibia fractures may result in insufficient reduction, malunion, and pin tract infection. Intramedullary nailing can be considered the “gold standard” for the treatment of tibial midshaft fractures, but there are concerns about their use in distal tibia fractures. This is because of technical difficulties with distal nail fixation, the risk of nail propagation into the ankle joint, and the discrepancy between the diaphyseal and metaphyseal diameter of the intramedullary canal. Open reduction and internal plate fixation results in extensive soft tissue dissection and may be associated with wound complications and infections. The optimal treatment of unstable distal tibia without articular involvement remains controversial. Objectives: This study was designed to review the outcomes of different treatment methods for extra-articular distal tibia fractures. The English literature was systematically reviewed and the rates of malunion, nonunion, infection, fixation failure, and secondary surgical procedures were extracted.

Stress radiographs after ankle fracture: the effect of ankle position and deltoid ligament status on medial clear space measurements.

Objective: This study was designed to determine 1) how ankle position affects the medial clear space by using stress radiographs, 2) which medial clear space measurement, overall width or increase in width, better predicts deep deltoid ligament disruption after Weber type-B distal fibular fracture, and 3) what value of medial clear space is most predictive of deep deltoid ligament disruption after Weber type-B distal fibular fracture. Design: Cadaveric fracture model. Setting: Biomechanics laboratory. Intervention: Fluoroscopic mortise views were taken of 6 fresh cadaveric ankles mounted in a fixture permitting both positioning in neutral flexion, dorsiflexion, and plantarflexion, and the application of internal and external rotational forces. After destabilizing the ankles according to the supination-external rotation mechanism of Lauge-Hansen, repeat radiographs were taken with the same combination of flexion and applied rotational stress. Main Outcome Measure: Radiographic measurements of medial clear space width and changes in medial clear space were made. Results: A medial clear space of ≥5 mm on radiographs taken in dorsiflexion with an external rotational stress was most predictive of deep deltoid ligament transection after distal fibular fracture. In dorsiflexion-external rotation, medial clear spaces of ≥4 mm yielded lower specificity and positive predictive value, whereas ≥6 mm yielded lower sensitivity and negative predictive value. All other stress conditions and increases in medial clear space of 2 or 3 mm were less predictive. Conclusions: Ankle stress radiographs taken in dorsiflexion-external rotation were most predictive of deep deltoid ligament disruption after distal fibular fracture. Under this stress condition, a medial clear space of ≥5 mm was the most reliable predictor of deep deltoid ligament status.

Does blood transfusion increase the risk of infection after hip fracture

OBJECTIVEnTo determine whether allogeneic red blood cell transfusion is a predictor for developing an in-hospital postoperative urinary tract, respiratory, or wound infection.nnnSTUDY DESIGNnProspective, consecutive.nnnMETHODSnSix hundred eighty-seven community-dwelling, ambulatory, geriatric hip fracture patients were prospectively followed; all patients had operative fracture treatment and received perioperative antibiotics.nnnRESULTSnSixty-eight patients had a culture-positive infection before operative treatment. One hundred thirty-four of the remaining 619 patients (21.6%) developed a postoperative infection, primarily a urinary tract infection. The infection rate was 26.8% in transfused patients compared with 14.9% in nontransfused patients (p = 0.001). When stratifying by the type of infection, only the risk of urinary tract infection was statistically significant (p = 0.001). After controlling for the effect of patient age, sex, number of preinjury medical comorbidities, American Society of Anesthesiologists (ASA) rating of operative risk, fracture type, surgical delay, type of surgery, type of anesthesia, operative time, and blood loss, the relationship between allogeneic red blood cell transfusion and postoperative urinal tract infection remained statistically significant.nnnCONCLUSIONSnGeriatric hip fracture patients who receive allogeneic red blood cell transfusions are at higher risk for developing a postoperative urinary tract infection than are those patients who are not transfused.

Is a Sliding Hip Screw or IM Nail the Preferred Implant for Intertrochanteric Fracture Fixation

This study was performed to determine whether patients who sustain an intertrochanteric fracture have better outcomes when stabilized using a sliding hip screw or an intramedullary nail. A 20% sample of Part A and B entitled Medicare beneficiaries 65xa0years or older was used to generate a cohort of patients who sustained intertrochanteric femur fractures between 1999 and 2001. Two fracture implant groups, intramedullary nail and sliding hip screw, were identified using Current Procedural Terminology and International Classification of Diseases, 9th Revision codes. The cohort consisted of 43,659 patients. Patients treated with an intramedullary nail had higher rates of revision surgery during the first year than those treated with a sliding hip screw (7.2% intramedullary nail versus 5.5% sliding hip screw). Mortality rates at 30xa0days (14.2% intramedullary nail versus 15.8% sliding hip screw) and 1xa0year (30.7% intramedullary nail versus 32.5% sliding hip screw) were similar. Adjusted secondary outcome measures showed significant increases in the intramedullary nail group relative to the sliding hip screw group for index hospital length of stay, days of rehabilitation services in the first 6xa0months after discharge, and total expenditures for doctor and hospital services.Level of Evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Addressing secondary prevention of osteoporosis in fracture care: follow-up to "own the bone".

The majority of the 1.8 million individuals who sustain a fracture annually in the United States have osteopenia or osteoporosis, yet <15% of these patients subsequently receive treatment for osteoporosis. A prospective cohort study was conducted to assess the effect of two different interventions on the rate of osteoporosis treatment in patients with a fragility fracture. Patients who were fifty years of age or older and were hospitalized for the treatment of a fragility fracture at either of two academic institutions were eligible for inclusion in the study. The intervention at one hospital involved immediate care for osteoporosis, including initiation of pharmacologic therapy during hospitalization. The intervention at the other hospital involved delayed care, including recommendations for osteoporosis counseling, bone-mineral density testing, and potential treatment for osteoporosis that were communicated to the primary care physician after the patient was discharged from the hospital. Patients were surveyed by telephone six months after the fracture, and their medical and pharmacy records were reviewed to verify the osteoporosis treatment that they had received. The mean age was 73 ± 10 years in the immediate-care group and 74 ± 12 years in the delayed-care group. Eighty percent of the patients were women. Sixty-five percent of the patients in each group completed the telephone interview six months after the fracture, and most had seen their primary care physician and undergone bone-mineral density testing. The rate of bone-mineral density testing was 92% in the immediate-care group compared with 76% in the delayed-care group. Both immediate and delayed care for osteoporosis resulted in a significant increase in the treatment rate compared with the baseline rate of 0% (p < 0.001). However, the primary care physician had initiated osteoporosis therapy by six months after the fracture in only 30% of the patients in the delayed-care group compared with a treatment rate of 67% in the immediate-care group (p < 0.001). Limitations of the study include the possibility that the findings resulted from a difference between the two study centers rather than between the two strategies. In addition, because of the academic and integrated nature of the medical systems at which the study was conducted, the findings cannot necessarily be extrapolated to other types of institutions. In summary, a recommendation for osteoporosis treatment made by an orthopaedic surgeon to the patients primary care physician resulted in an increase in the rate of bone-mineral density testing and in the rate of therapy compared with baseline. However, immediate initiation of osteoporosis care during hospitalization for the fragility fracture resulted in a higher rate of treatment--with two-thirds of the patients receiving therapy six months after the fracture--compared with delayed initiation.

Biomechanical comparison of the sliding hip screw and the dome plunger. Effects of material and fixation design

We studied the biomechanical behaviour of three sliding fixation devices for trochanteric femoral fractures. These were a titanium alloy sideplate and lag screw, a titanium alloy sideplate and dome plunger with cement augmentation, and a stainless-steel sideplate and lag screw. We used 18 mildly osteoporotic cadaver femora, randomly assigned to one of the three fixation groups. Four displacement and two strain gauges were fixed to each specimen, and each femur was first tested intact (control), then as a two-part fracture and then as a four-part intertrochanteric fracture. A range of physiological loads was applied to determine load-bearing, load-sharing and head displacement. The four-part-fracture specimens were subsequently tested to failure to determine maximum fixation strengths and modes of failure. The dome-plunger group failed at a load 50% higher than that of the stainless-steel lag-screw group (p < 0.05) and at a load 20% higher than that of the titanium-alloy lag-screw group (NS). All 12 lag-screw specimens failed by cut-out through the femoral head or neck, but none of the dome-plunger group showed movement within the femoral head when tested to failure. Strain-gauge analysis showed that the dome plunger produced considerably less strain in the inferior neck and calcar region than either of the lag screws. Inferior displacement of the femoral head was greatest for the dome-plunger group, and was due to sliding of the plunger. The dome plunger with cement augmentation was able to support higher loads and did not fail by cut-out through the femoral head.(ABSTRACT TRUNCATED AT 250 WORDS)