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Biomedical subjects

Madhav A Karunakar

Publications and source records attributed to Madhav A Karunakar.

At least 19 recordsLinked to original sources
PubMed2007

Safe zone for the placement of medial malleolar screws.

BACKGROUND: Hardware placement for fracture fixation can put soft-tissue structures at risk for injury or abutment. The prominence of the hardware is a frequent cause of pain after the fixation of ankle fractures. This study was designed to assess the risk of injury or abutment of the posterior tibial tendon with the placement of medial malleolar screws. METHODS: Ten unmatched cadaveric limbs that had been disarticulated at the knee were used, and the medial malleolus was exposed by dissection of the skin. With use of fluoroscopy and direct visualization of the deep fascia, three Kirschner wires were placed through the tip of the medial malleolus and directed parallel to the medial articular surface. The first wire was placed in the center of the anterior colliculus. Two additional wires were placed parallel and posterior to the initial wire at 5-mm intervals. The wires were overdrilled, and 4.0-mm screws were inserted over the Kirschner wires. The specimens were dissected to inspect for trauma and the proximity of the screws to the posterior tibial tendon. The medial malleolus was divided into three zones on the basis of anatomic landmarks. Zone 1 is the anterior colliculus; Zone 2, the intercollicular groove; and Zone 3, the posterior colliculus. RESULTS: Screws placed in Zone 1 (the anterior colliculus) did not contact the posterior tibial tendon in any specimens. Screws placed in Zone 2 (the intercollicular groove) were, on the average, 2 mm from the posterior tibial tendon. Screws placed in Zone 3 (the posterior colliculus) resulted in tendon abutment in all ten specimens and in tendon injury in five of the ten specimens. CONCLUSIONS: Screws inserted posterior to the anterior colliculus place the posterior tibial tendon at significant risk for injury or abutment.

Adult↗
PubMed2006

Classification of common acetabular fractures: radiographic and CT appearances.

OBJECTIVE: Accurate characterization of acetabular fractures can be difficult because of the complex acetabular anatomy and the many fracture patterns. In this article, the five most common acetabular fractures are reviewed: both-column, T-shaped, transverse, transverse with posterior wall, and isolated posterior wall. Fracture patterns on radiography are correlated with CT, including multiplanar reconstruction and 3D surface rendering. CONCLUSION: In the evaluation of the five most common acetabular fractures, assessment of the obturator ring, followed by the iliopectineal and ilioischial lines and iliac wing, for fracture allows accurate classification. CT is helpful in understanding the various fracture patterns.

Acetabulum↗
PubMed2006

Surgical treatment of nonarticular distal tibia fractures.

Distal tibia metaphyseal fractures can be difficult to manage. Treatment selection is influenced by the proximity of the fracture to the plafond, fracture displacement, comminution, and injury to the soft-tissue envelope. Nonsurgical management is possible for stable fractures with minimal shortening. Indications for intramedullary nailing have expanded to include distal metaphyseal tibia fractures. Intramedullary nailing allows atraumatic, closed stabilization while preserving the vascularity of the fracture site and integrity of the soft-tissue envelope. Intramedullary canal anatomy at this level prevents intimate contact between the nail and endosteum, however, and concerns have been raised regarding the biomechanical stability of fixation and risk of malunion. Plate fixation is effective in stabilizing distal tibia fractures. Conventional techniques involve extensive dissection and periosteal stripping, which increase the risk of soft-tissue complications. Percutaneous plating techniques use indirect reduction methods and allow stabilization of distal tibia fractures while preserving vascularity of the soft-tissue envelope. External fixation is effective in the setting of contaminated wounds or extensive soft-tissue injury. Careful preoperative planning with consideration for fracture pattern and soft-tissue condition helps guide implant selection and minimize postoperative complications.

Bone Nails↗
PubMed2006

Physiologic effects of intramedullary reaming.

Reaming has a significant biologic and mechanical impact on the physiology of fracture healing. A review of the thermal, pulmonary, and osteogenic effects of reaming can provide evidence-based guidelines to assist the clinician in improving patient outcomes. Thermal necrosis is a rare but commonly referenced complication of reaming. The risks of heat-induced cortical damage can be minimized by sequential reaming with sharp instruments and by reaming with instruments that are sized appropriately to fit the intramedullary canal. The use of a tourniquet while reaming does not increase the risk of thermal necrosis. Reaming results in increased intramedullary pressure and secondary embolization of marrow elements to the pulmonary system. The clinical significance of these embolic events remains controversial. Potential complications can be reduced by using reamer designs and techniques that minimize the increases in intramedullary pressure. Outcome studies consistently show that reaming potentiates the healing response with intramedullary fixation of long-bone fractures. Recent laboratory studies implicate alterations in cortical blood flow patterns and the osteogenic potential of reaming debris as critical components of this process.

Blood Flow Velocity↗
PubMed2006

Complete traumatic extrusion of the distal ulna through the hypothenar eminence: a case report.

We present a case of complete traumatic extrusion of the distal 40% of the ulna through the hypothenar eminence in the context of an open, both-bone forearm fracture and spinal cord transection. To the best of our knowledge, this specific trauma is unique to the literature, and, therefore, there is no standard treatment approach. Our patient was managed with irrigation and débridement along with open reduction and internal fixation of the radius fracture. No reconstruction of the ulna was performed. The patient reported excellent functional results at 13-month follow-up.

Accidents, Traffic↗
PubMed2005

Hemiarthroplasty for femoral neck fracture in the elderly surgeon and hospital volume-related outcomes.

The elderly patient with a displaced femoral neck fracture is commonly treated via hemiarthroplasty. The objectives of this study were to: 1) determine the rates of in-hospital mortality, complications, and prolonged length of stay (LOS) in such patients; 2) elucidate the patient characteristics that predict these occurrences; and 3) investigate the influence of surgeon and hospital volumes on these outcomes. Using the Nationwide Inpatient Sample (NIS), 173,508 cases of hemiarthroplasty for femoral neck fracture were identified in patients > or =65 years of age. Univariate and multivariate analysis demonstrated that hospitals with low caseload volumes were associated with increased patient risk for prolonged LOS, pulmonary embolism, urinary tract infection, and pneumonia. Surgeons with low caseload volumes were associated with increased risk for mortality and prolonged LOS. Quality-improvement initiatives would benefit from consideration of these factors.

Aged↗
PubMed2005

Body mass index as a predictor of complications after operative treatment of acetabular fractures.

BACKGROUND: Obesity, a growing public health concern, is often thought to be an important risk factor for postoperative complications. We hypothesized that body mass index is predictive of complications after operative treatment of acetabular fractures. METHODS: A retrospective chart review identified 169 consecutive patients in whom an acetabular fracture had been treated with open reduction and internal fixation at a level-1 trauma center. The patients were stratified into four classes according to their body mass index: normal (<25), overweight (> or =25 but <30), obese (> or =30 but <40), and morbidly > or =40). The perioperative outcomes that were evaluated included estimated blood loss, wound infection, nerve palsy, deep venous thrombosis, pulmonary embolism, and heterotopic ossification. Multivariate general linear models were used to test for the relationship between body mass index and perioperative outcomes while controlling for potential intervening variables (including surgical approach, fracture type, and surgeon experience). Odds ratios were calculated as well. RESULTS: When body mass index was measured as a continuous variable, it was found to have a significant relationship with estimated blood loss (p = 0.003), prevalence of wound infection (p = 0.002), and prevalence of deep venous thrombosis (p = 0.03). Odds ratio analysis revealed that obese subjects (body mass index of > or =30) were 2.1 times more likely than patients of normal weight (body mass index of <25) to have an estimated blood loss of >750 mL and 2.6 times more likely to have a deep venous thrombosis. Morbidly obese patients (body mass index of > or =40) were five times more likely to have a wound infection. CONCLUSIONS: Body mass index is predictive of complications after operative treatment of acetabular fractures.

Acetabulum↗
PubMed2005

The use of ultrasound in evaluating orthopaedic trauma patients.

Musculoskeletal ultrasound is a low-cost, noninvasive method of evaluating orthopaedic trauma patients. It is particularly useful for patients with metallic hardware, which may degrade computed tomography or magnetic resonance images. Ultrasound has been used to evaluate fracture union and nonunion, infection, ligamentous injury, nerve compression, and mechanical impingement caused by hardware. Real-time dynamic examination allows identification of pathology and provides direct correlation between symptoms and the observed pathology.

Humans↗
PubMed2005

A case series and review of salvage surgery for refractory humeral shaft nonunion following two or more prior surgical procedures.

The orthopedic surgery literature is replete with techniques for managing primary humeral shaft nonunions, with success rates upwards of 90 percent with plate fixation and autogenous bone grafting. Despite this success, persistent nonunion following one or more initial failed nonunion interventions can occur, imposing a significant clinical and surgical challenge. We report the application of a standard treatment protocol for refractory humeral shaft nonunions including optimization of patient co-morbidities in the peri-operative period, rigid 4.5mm compression plating with a minimum of eight cortices of fixation proximal and distal to the nonunion site, and utilization of autogenous bone grafting. This study, a retrospective review of seven patients, all managed based on this standard treatment protocol, revealed that all achieved fracture nonunion within six months of revision surgery. Six of seven patients were clinically satisfied with the outcome of surgery; one remained dissatisfied secondary to a chronic neuropathic pain syndrome. Although more complex surgical options such as Ilizarov external fixation and allograft cortical strut augmentation have been reported, and are available in the salvage situation of refractory humeral nonunions, we conclude strict application of basic nonunion principles can result in successful salvage of humerus nonunions in patients who have failed two or more prior surgical interventions.

Adult↗
PubMed2004

Femoral head fractures: diagnosis, management, and complications.

Femoral head fractures occur with a reported incidence of 6%-16% after hip dislocation. Even the largest series have evaluated only a few dozen patients, often collecting experience from multiple centers. This article provides the clinician with current information to guide the diagnosis and treatment of this uncommon condition.

Female↗
PubMed2004

The modified ilioinguinal approach.

A modified ilioinguinal approach for acetabular fractures is presented. The approach allows surgical exposure of the anterior column as well as the contralateral rami, the symphysis pubis, and the medial wall of the acetabulum. Direct access to the quadrilateral surface and retroacetabular surface for plate or screw application is also possible.

Abdominal Muscles↗
PubMed2004

Avoiding malunion with 95degrees fixed-angle distal femoral implants.

Malunion of the distal end segment of a fractured femur is a common complication after open reduction and internal fixation when using 95degrees fixed-angle devices. Incorrect positioning of the alignment Kirschner wires can result in implant malposition and subsequent malunion. This article discusses the relevant distal femoral anatomy and the technical points necessary to avoid a malunion when using 95degrees fixed-angle devices.

Bone Plates↗
PubMed2003

Bicondylar tibial plateau fractures: a biomechanical study.

The optimal treatment of bicondylar tibial plateau fractures remains controversial. The current study was designed to answer the following questions: (1) can a lateral fixed angle plate provide similar construct stability to dual plating techniques and (2) does the size of the medial buttress plate used in dual plating techniques have an effect on construct stability? Bicondylar tibial plateau fractures were created, reduced, and instrumented in a matched pair design using a cadaveric simulated bicondylar tibial plateau fracture model. Tibias were instrumented with one of three constructs: a lateral periarticular plate and posteromedial small fragment dynamic compression plate, a lateral periarticular plate and posteromedial (1/3)-tubular plate, or a lateral fixed angle plate. Biomechanical testing was done to determine construct stiffness, maximum load to failure, and medial condylar displacement for each of the three constructs. There was no significant difference measured between the two dual plating constructs and the lateral fixed angle plate for overall construct stiffness or with respect to medial condylar fragment displacement. A lateral fixed angle plate may have clinical applications in the treatment of bicondylar tibial plateau fractures.

Aged↗
PubMed2003

Sonographic evaluation of lower extremity interosseous membrane injuries: retrospective review in 3 patients.

OBJECTIVE: To describe the sonographic findings of lower extremity interosseous membrane disruption with computed tomographic and surgical correlation. METHODS: Three patients with sonographic evaluation of the lower extremity interosseous membrane were identified through the clinical experience of 1 author over a 5-year period. Sonographic images of the symptomatic and unaffected lower extremities were retrospectively characterized and correlated with computed tomographic and surgical findings by 2 fellowship-trained musculoskeletal radiologists. RESULTS: The normal interosseous membrane was identified in the asymptomatic lower extremities in all 3 patients, which appeared as a thin, hyperechoic (nearly equal to bone cortex) line, continuous from the tibia to the fibula. The abnormal interosseous membrane in all 3 cases appeared abnormally hypoechoic, poorly defined, and discontinuous at the tibia. A proximal fibular fracture was shown on sonography in 1 of 3 symptomatic lower extremities with radiographic evidence of a fracture. The sonographic findings correlated with the computed tomographic images. Distal tibiofibular syndesmosis injuries were confirmed and treated at surgery in 2 patients. CONCLUSIONS: Sonography can show both normal and injured interosseous membranes of the lower extremity, as well as associated proximal fibular fractures.

Adult↗
PubMed2002

Split depression tibial plateau fractures: a biomechanical study.

OBJECTIVE: To determine the biomechanical characteristics of four different fixation constructs for split depression fractures of the lateral tibial plateau (OTA classification 41B3.1). DESIGN: Laboratory investigation using a cadaveric simulated split depression tibial plateau fracture model. SETTING: Split depression tibial plateau fractures were created, reduced, and instrumented in a matched pair design. Specimens were tested for stiffness using a materials testing machine. INTERVENTION: Tibias were instrumented with an L-buttress plate, four 3.5-millimeter subchondral raft screws with an antiglide plate, an L-buttress plate with cancellous allograft, or four 3.5-millimeter subchondral raft screws placed through a periarticular plate. MAIN OUTCOME MEASUREMENTS: Vertical subsidence of the lateral tibial plateau was measured for the entire construct and for the local depression. The relative medial and lateral condylar tilt with central loading was also measured. RESULTS: There was no significant difference between the four fixation methods for overall longitudinal stiffness of the proximal tibial fracture fixation construct (range, 2,026 to 2,666 newtons per millimeter). The local depression stiffness for the raft-periarticular plate and raft-antiglide plate were 425 newtons per millimeter and 342 newtons per millimeter, respectively, versus 243 newtons per millimeter and 210 newtons per millimeter for the two large fragment buttress constructs. There was no significant difference between the local depression stiffness for the two raft constructs. There was no significant difference between the local depression stiffness for the two buttress plate constructs. Local depression stiffness was found to be significantly greater for the raft-periarticular plate construct when compared with the large fragment buttress plate construct without bone graft (p = 0.0314). Condylar tilt data showed a significant difference between the medial tilt observed in the prefracture specimen and the lateral tilt observed after fixation (p less-than-or-equal 0.017) for all constructs. CONCLUSIONS: There was no significant difference in the overall construct stiffness between the four fixation constructs. Fixation constructs with a raft of subchondral screws were more resistant to local depression loads. This supports the use of a raft construct when a central depression is a significant component of the overall fracture pattern. Condylar tilt data showed a persistent weakness in the postfixation lateral plateau regardless of fixation construct when compared with the intact specimen. This supports the current clinical practice of delayed weight-bearing for ten to twelve weeks.

Biomechanical Phenomena↗
PubMedDate not supplied

Operative treatment of unstable pediatric pelvis and acetabular fractures.

The management of unstable pediatric pelvic and acetabular fractures continues to be controversial. Recent reports have suggested that closed management of unstable pelvic and acetabular fractures can result in significant long-term morbidity. The purpose of this study was to evaluate the results of operative stabilization of unstable pelvic and acetabular fractures in children and adolescents. Eighteen patients less than 16 years of age with unstable pelvic and acetabular fractures were treated operatively over a 7-year period. Fracture healing, time to union, complications, and functional outcome were assessed. All fractures healed by 10 weeks. No patients suffered wound complications, infection, or growth arrest at an average follow-up of 30 months. These results support operative fixation of unstable pediatric pelvic and acetabular fractures to restore pelvic symmetry and periarticular anatomy. Favorable clinical results can be achieved with a low incidence of complications.

Acetabulum↗