Treatment of tibial plateau fractures with a novel fenestrated screw system for delivery of bone graft substitute.

PURPOSE: The purpose of this study was to describe the incidence of subsidence in patients with AO/OTA 41 (tibial plateau) fractures which were repaired with a novel fenestrated screw system to used to deliver CaPO4 bone substitute material to fill the subchondral void and support the articular reduction. METHODS: Patients with unicondylar and bicondylar tibial plateau fractures were treated according to the usual technique of two surgeons. After fixation, the Zimmer Biomet N-Force Fixation System®, a fenestrated screw that allows for the injection of bone substitute was placed and used for injection of the proprietary calcium phosphate bone graft substitute into the subchondral void. For all included patients, demographic information, operative data, radiographs, and clinic notes were reviewed. Patients were considered to have articular subsidence if one or more of two observations were made when comparing post-operative to their most recent clinic radiographs: > 2 mm change in the distance between the screw and the lowest point of the tibial plateau, > 2 mm change in the distance between the screw and the most superior aspect of the plate. Data were analyzed to determine if there were any identifiable risk factors for complication, reoperation, or subsidence using logistic regression. Statistical significance was set at p < 0.05. RESULTS: 34 patients were included with an average follow-up of 32.03 ± 22.52 weeks. There were no overall differences between height relative to the medial plateau or the plate. Two patients (5.9%) had articular subsidence. Six patients (15.2%) underwent reoperation, two (6%) for manipulations under anaesthesia due to arthrofibrosis, and four (12%) due to infections. There were 6 (19%) total infections as 2 were superficial and required solely antibiotics. One patient had early failure. CONCLUSION: Use of a novel fenestrated screw system for the delivery of CaPO4 BSM results in articular subsidence and complication rates similar to previously published values and appears to be a viable option for addressing subchondral defects in tibial plateau fractures. LEVEL OF EVIDENCE: IV.

Treatment of Pediatric and Adolescent Pelvic Ring Injuries With Percutaneous Screw Placement.

BACKGROUND: Pediatric and adolescent pelvic ring injuries are frequently treated without surgery. In patients with unstable injuries to the pelvic ring, surgical stabilization aids in resuscitation, provides pain relief, and allows for mobilization. Percutaneous pelvic screw fixation is commonly performed in adult patients for unstable pelvic ring injuries, but a paucity of literature exists regarding their use in pediatric patients. The purpose of this study is to review the use, outcome, and management of percutaneous posterior pelvic screws in pediatric patients with unstable pelvic ring injuries. METHODS: A retrospective review of a prospectively collected orthopaedic trauma database was performed over a 7-year period at a regional level-1 trauma center. All patients between the ages of 7 and 17 who sustained an injury to the pelvic ring and were treated with percutaneous fixation of the posterior pelvic ring were identified. We evaluated the frequency of this technique in the described patient population, incidence of nerve injury, infection, loss of fixation, and need for hardware removal. RESULTS: A total of 238 pediatric patients who sustained a pelvic ring injury were initially identified; following application of study criteria, 67 (28.1%) patients were included in the study. Additional anterior ring fixation was performed in 33 (49.2%) patients. There were no iatrogenic nerve injuries, no infections, and surgical blood loss was <50 mL in all cases. Clinical and radiographic follow-up averaged 33 weeks. No loss of reduction was observed. Eight patients (13%) reported persistent low back pain at last follow-up. Elective hardware removal was performed in 3 patients. CONCLUSIONS: The majority of pediatric pelvic ring injuries can be treated without surgery. In the setting of instability, percutaneous pelvic screw fixation can be performed safely. A computed tomography scan is used to evaluate the available osseous pathways for screws and intraoperative fluoroscopy is used to safely perform this technique. Screw removal should be discussed in select patients. LEVEL OF EVIDENCE: Level IV.

Management and radiographic outcomes of femoral head fractures.

BACKGROUND: Femoral head fractures are uncommon injuries. Small series constitute the majority of the available literature. Surgical approach and fracture management is variable. The purpose of this study was to evaluate the incidence, method of treatment, and outcomes of consecutive femoral head fractures at a regional academic Level I trauma center. MATERIALS AND METHODS: A retrospective review of a prospective database was performed over a 13-year period. All AO/OTA 31C femoral head fractures were identified. A surgical approach and fixation method was recorded. Clinical and radiographic evaluation was performed for patients with 6 months or greater follow-up. Radiographs were evaluated for fixation failure, heterotopic ossification (HO), avascular necrosis (AVN) and post-traumatic arthritis. RESULTS: We identified 164 fractures in 163 patients; 147 fractures were available for review. Treatment was operative reduction and internal fixation (ORIF) in 78 (53.1%), fragment excision in 37 (25.1%) and non-operative in 28 (19%). An anterior approach and mini-fragment screws were used in the majority of patients treated with fixation. Sixty-nine fractures had follow-up greater than 6 months. Sixty-two fractures (89.9%) proceeded to uneventful union. All Pipkin III fractures failed operative fixation. Six patients developed AVN, seven patients had a known conversion to hip arthroplasty; HO developed in 28 (40.6%) patients and rarely required excision. CONCLUSIONS: Fractures of the femoral head are rare. An anterior approach can be used for fragment excision or fixation using mini-fragment screws. Pipkin III fractures represent catastrophic injuries. Non-bridging, asymptomatic HO is common. AVN and posttraumatic degenerative disease of the hip occur but are uncommon. LEVEL OF EVIDENCE: IV-prognostic.

Venous thromboembolism in orthopaedic trauma.

Patients who sustain orthopaedic trauma are at risk for developing deep venous thrombosis and symptomatic pulmonary emboli. The prevention of venous thromboembolism has moved to the forefront of patient safety initiatives, resulting in the formation of various guidelines to assist the practitioner. Recommendations for venous thromboembolism prophylaxis in the orthopaedic trauma patient exist, but there is insufficient evidence in the literature to make strong recommendations regarding type and duration of prophylaxis. The associated morbidity of chemical anticoagulants used in the orthopaedic trauma patient must also be taken into consideration, specifically the increased risk of bleeding. Mechanical prophylaxis is used in place of, or in addition to, these medications in certain situations. New, potentially superior anticoagulants have been developed but are still understudied. Larger studies are needed to further define the type and duration of deep venous thrombosis prophylaxis in the orthopaedic trauma patient.

Open surgical management of high energy ipsilateral fractures of the fibula and calcaneus.

BACKGROUND: Simultaneous ipsilateral fractures of the calcaneus and fibula are the result of high-energy injuries. Open surgical treatment of both fractures can be performed with incisions based on the described blood supply of the lower extremity. METHODS: A retrospective review for all patients with ipsilateral fractures of the calcaneus and fibula was performed over an eight-year period. Thirty-eight patients were identified. Eleven patients (28.9%) were treated with open reduction and internal fixation through two separate incisions. Average follow-up was 48.8 weeks. RESULTS: Two patients (18.1%) required a secondary procedure. Three patients (27.2%) developed incisional cellulitis that resolved with oral antibiotics and one patient required local wound care. All fractures united. CONCLUSIONS: Ipsilateral fractures of the calcaneus and fibula require open reduction and internal fixation when closed or percutaneous treatment is not appropriate. We describe an operative approach based on the angiosomes of the lower extremity that allows for treatment of these complex injuries and report the associated complications.

Isolated pelvic ring injuries: functional outcomes following percutaneous, posterior fixation.

OBJECTIVES: To characterize pelvic-specific functional outcomes in patients with isolated, partially unstable (AO/OTA 61-B), pelvic ring injuries treated with posterior only percutaneous screw fixation of the pelvic ring. PATIENTS AND METHODS: Between September 2007 and October 2011, 16 subjects (mean age 42.4 years; range 18-90 years) with isolated, partially unstable pelvic ring injuries (AO/OTA 61-B) were treated with percutaneous, posterior pelvic ring fixation. Subjects underwent an evaluation of pelvic ring function with a modification of Majeed's pelvic functional outcome assessment tool. Subjects were excluded if they sustained a concomitant long-bone fracture, visceral injury requiring surgery, spinal cord injury, and an injury to the anterior pelvic ring or acetabulum requiring additional fixation. RESULT: Mean follow-up was 30.8 (range 14-55) months. Eleven subjects sustained unilateral posterior ring injuries, and five subjects sustained bilateral posterior ring injuries. All fractures healed uneventfully, and no hardware failures were noted. Average pelvic functional outcome score at final follow-up was 85.3 % (good). All but subjects required assistive walking devices and gait and sitting comfort scored "excellent." High rates of sexual dysfunction and persistent difficulty with daily activities were noted in this series. CONCLUSIONS: This series demonstrates that activity-specific dysfunction persists years after definitive percutaneous posterior fixation of isolated pelvic ring injuries. Radiographic outcomes were excellent as were subjects' ability to ambulate independently and sit comfortably without pain. Many complained of persistent discomfort with both daily activities and sexual activity, suggesting persistent pathology to the non-osseous structures about the pelvis.

Surgical fixation of extra-articular distal humerus fractures with a posterolateral plate through a triceps-reflecting technique.

BACKGROUND: Surgical management of extra-articular distal humerus fractures results in predictable fracture alignment. Open reduction and internal fixation also decrease the soft tissue complications and frequent follow-up required with functional bracing. A triceps-reflecting posterior approach provides excellent exposure to the humerus and minimizes trauma to the triceps. An anatomically precontoured plate on the posterolateral surface of the humerus provides stable fixation of these injuries and is placed directly through the interval developed by the triceps-reflecting approach. METHODS: We retrospectively reviewed the trauma databases at 2 level I academic trauma institutions during a 5-year period for all patients with an extra-articular distal humerus fracture treated with a triceps-reflecting approach and an anatomically precontoured posterolateral distal humerus plate. Patient and fracture characteristics were recorded, as were QuickDASH functional scores and visual analog scale scores for pain, function, and quality of life. RESULTS: Forty patients were eligible for our study. Average follow-up was 88 weeks. Thirty-eight (95%) patients went on to union. Seven (20%) patients required a secondary procedure. The average QuickDASH score was 17.5 (range, 2.6-56.8). The average visual analog scale scores were 1.9 (range, 0-7) for pain, 2.3 (range, 0-8) for function, and 1.6 (range, 0-5) for quality of life. Thirty-five (87.5%) patients reported satisfaction with the outcome of their surgery. DISCUSSION: Surgical fixation of extra-articular distal humerus fractures through a triceps-reflecting approach with an anatomically precontoured posterolateral distal humerus plate results in predictable osseous union and overall excellent functional results for patients with this injury.

The pubic midline exposure for symphyseal open reduction and plate fixation.

BACKGROUND: Open reduction and plate fixation of the disrupted symphysis pubis is commonly performed through a horizontal Pfannenstiel incision. Certain clinical situations that complicate the soft tissue conditions of the lower abdomen may make the Pfannenstiel incision a less appealing option. We report on the use of a vertical pubic area midline skin incision in a series of patients undergoing open reduction and plate fixation of their traumatically disrupted symphysis pubis. MATERIALS AND METHODS: Institutional Review Board approval was obtained for a retrospective chart review of the charts of 25 patients treated between September 2011 and October 2012. Their charts were reviewed for patient age, gender, body mass index (BMI), pelvic injury type (as classified by Young and Burgess), mechanism of injury and associated traumatic injuries. The depth of the approach was estimated using the pelvic computed tomography (CT) scan. Details from the operative procedure were recorded, as was the length of follow-up and any perioperative complications. RESULTS: Twenty-five patients were eligible for inclusion during the defined study time period between September 2011 and October 2012. The patients' average age was 55.8 years (range 25-91). All patients were males. The average BMI was 29.3 (range 18.8-43.8). The depth measured on the axial pelvic CT scan from skin to symphysis was 57.6 mm (range 35.2-90.2 mm). Five of 25 patients had an isolated pelvic ring injury without other associated injuries. The injury pattern was APC2 in 18, APC3 in 3, LC2 in 2, LC3 in 1 and VS in 1 patient(s) [anterior posterior compression (APC), lateral compression (LC), vertical shear (VS)]. Urologic procedures were performed in the same surgical setting in four patients. The average blood loss was 244 ml (range 150-400 ml). The average follow-up was 2.5 months (range 1-12 months). Perioperative issues were noted in two patients. One patient died within a month of surgery as a result of his associated traumatic injuries. One patient developed a deep infection. CONCLUSION: The pubic midline skin exposure is a feasible alternative to the Pfannenstiel incision for open reduction and plate fixation of the pubic symphysis. LEVEL OF EVIDENCE: IV, Retrospective case series.

Perioperative Considerations for Use of Custom Metallic Implants in Limb Reconstruction.

SUMMARY: The surgical management of critical bone defects remains challenging. Regardless of whether bone loss is acute or the result of staged surgical resection, current surgical management often requires advanced reconstructive techniques, many of which require multiple surgical procedures and consistent patient involvement with applied internal or external orthopaedic devices. The utilization of three-dimensional (3D) printing technology has continued to expand across orthopaedic subspecialties; in orthopaedic trauma, custom metallic implants are being used in the management of critical bone defects. Implementation of this technique may be advantageous in certain clinical situations. The perioperative considerations for placement of a custom bone defect printed metallic implant are presented in conjunction with demonstrative clinical cases.

Outcomes of isolated medial tibial plateau fractures by fracture morphology.

PURPOSE: To identify a cohort of isolated medial tibial plateau fractures treated with surgical fixation and to categorize them by Moore and Wahlquist classifications in order to determine the rate of complications with each fracture morphology and the predictive value of each classification system. We hypothesized there would be high rates of neurovascular injury, compartment syndrome, and complications overall with a higher incidence of neurovascular injury in Moore type III rim avulsion fractures and Wahlquist type C fractures that enter the plateau lateral to the tibial spines. METHODS: Patients who presented to six Level I trauma centers between 2010 and 2021 who underwent surgical fixation for isolated medial tibial plateau fractures were retrospectively reviewed. Data including demographics, radiographs, complications, and functional outcomes were collected. RESULTS: One hundred and fifty isolated medial tibial plateau fractures were included. All patients were classified by the Wahlquist classification of medial tibial plateau fractures, and 139 patients were classifiable by the Moore classification of tibial plateau fracture-dislocations. Nine percent of fractures presented with neurovascular injury: 5 % with isolated vascular injury and 6 % with isolated nerve injury. There were no significant differences in neurovascular injury by fracture type (Wahlquist p = 0.16, Moore p = 0.33). Compartment syndrome developed in two patients (1.3 %). The average final range of motion was 0.8-122° with no difference by Wahlquist or Moore classifications (p = 0.11, p = 0.52). The overall complication rate was 32 % without differences by fracture morphology. The overall rate of return to the operating room (OR) was 25 %. CONCLUSIONS: Isolated medial tibial plateau fractures often represent fracture-dislocations of the knee and should receive a meticulous neurovascular exam on presentation with a high suspicion for neurovascular injury. No specific fracture pattern was found to be predictive of neurovascular injuries, complications, or final knee range of motion. Patients should be counseled pre-operatively regarding high rates of return to the OR after the index surgery.

Intraosseous correction of misdirected cannulated screws and fracture malalignment using a bent tip 2.0 mm guidewire: technique and indications.

Percutaneous pelvic screw placement is a technically demanding procedure. A precise intraosseous pathway must be prepared before screw placement into any osseous fixation pathway of the pelvis. Adjustments to a drill or guidewire become increasingly difficult as the instrument is advanced within the pelvis. We present a reliable and reproducible technique using a 2.0 mm guidewire that allows for correction of an initially misdirected drill within the pelvis. This technique also allows for manipulation and reduction of certain malaligned pelvic fractures prior to percutaneous cannulated screw placement. This technique does not substitute for poor surgical technique but is used to optimize the position of percutaneously placed pelvic screws.

Orthopaedic Advances: Use of Three-Dimensional Metallic Implants for Reconstruction of Critical Bone Defects After Trauma.

Multiple successful strategies exist for the management of critical-sized bone defects. Depending on the location and etiology of an osseous defect, there are nuances that must be considered by the treating surgeon. The induced membrane technique and various modifications of the Ilizarov method (bone transport by distraction osteogenesis) have been the most common methods for biologic reconstruction. Despite the versatility and high union rates reported, they may not be practical for every patient. The rapid expansion of three-dimensional printing of medical devices has led to an increase in their use within orthopaedic surgery, specifically in the definitive treatment of critical bone defects. This article proposes indications and contraindications for implementation of this technology and reviews the available clinical evidence on the use of custom nonresorbable implants for the treatment of traumatic bone loss. Clinical cases are presented to illustrate the scenarios in which this approach is viable.

Cannabinoids for Pain Modulation in Orthopedic Surgery.

Cannabinoid compounds are being increasingly used as an analgesic adjuvant in the orthopedic population, but little data exist to either support or oppose this practice pattern. A review of all contemporary (2000-2020) studies on the use of cannabinoids in orthopedics is presented. Physicians and patients are optimistic that cannabinoids can decrease pain scores and perhaps opioid use; however, their application in orthopedics is not well characterized. In addition to the social stigma regarding the use of cannabis, there is limited high-quality evidence of the efficacy of cannabinoids in treating orthopedic-related pain. As cannabis becomes more accessible, well-designed trials are needed to better understand cannabinoids and guide orthopedic practice. [Orthopedics. 2022;45(6):e295-e302.].

Chemoprophylaxis for venous thromboembolism in pelvic and/or acetabular fractures: A systematic review.

BACKGROUND: It is unclear which pharmacological agents, and at what dosage and timing, are most effective for venous thromboembolism (VTE) prophylaxis in patients with pelvic/acetabular fractures. METHODS: We searched the Cochrane Database of Systematic Reviews, Embase, Web of Science, EBSCO, and PubMed on October 3, 2020, for English-language studies of VTE prophylaxis in patients with pelvic/acetabular fractures. We applied no date limits. We included studies that compared efficacy of pharmacological agents for VTE prophylaxis, timing of administration of such agents, and/or dosage of such agents. We recorded interventions, sample sizes, and VTE incidence, including deep vein thrombosis (DVT) and pulmonary embolism. RESULTS: Two studies (3604 patients) compared pharmacological agents, reporting that patients who received direct oral anticoagulants (DOACs) were less likely to develop DVT than those who received low molecular weight heparin (LMWH) (p < 0.01). Compared with unfractionated heparin (UH), LMWH was associated with lower odds of VTE (odds ratio [OR] = 0.37, 95% confidence interval [CI]: 0.22-0.63) and death (OR = 0.27, 95% CI: 0.10-0.72). Three studies (3107 patients) compared timing of VTE prophylaxis, reporting that late prophylaxis was associated with higher odds of VTE (OR = 1.9, 95% CI: 1.2-3.2) and death (OR = 4.0, 95% CI: 1.5-11) and higher rates of symptomatic DVT (9.2% vs. 2.5%, p = 0.03; and 22% vs. 3.1%, p = 0.01). One study (31 patients) investigated dosage of VTE prophylaxis, reporting that a higher proportion of patients with acetabular fractures were underdosed (23% of patients below range of anti-Factor Xa [aFXa] had acetabular fractures vs. 4.8% of patients within adequate range of aFXa, p<0.01). CONCLUSIONS: Early VTE chemoprophylaxis (within 24 or 48 h after injury) was better than late administration in terms of VTE and death. Many patients with acetabular fractures are underdosed with LMWH, with inadequate aFXa levels. Compared with UH, LMWH was associated with lower odds of VTE and death. DOACs were associated with lower risk of DVT compared with LMWH. LEVEL OF EVIDENCE: III, systematic review of retrospective cohort studies.

Suture Augmentation Neutralizes Deforming Muscular Forces in a Simulated 2-Part Osteoporotic Proximal Humeral Fracture Model.

OBJECTIVES: To evaluate the contribution that tension-relieving sutures, placed between a proximal humeral locking plate and the rotator cuff muscles, had on preventing varus malalignment in an osteoporotic 2-part proximal humerus fracture model. METHODS: A 2-part fracture model was created in 8 cadaveric specimens and then fixed with a lateral locking plate. A custom shoulder testing system was used to increase loading through the supraspinatus (SS) tendon to drive varus deformity. Trials were performed with no suture placement; SS only; SS and subscapularis (SB); and SS, SB, and infraspinatus. The primary outcome was contribution of each point of suture fixation to prevention of varus collapse. RESULTS: Suture augmentation to the SS, SB, and infraspinatus significantly decreased humeral head varus collapse when compared with the plate alone at nearly all loads ( P < 0.05). There were no significant differences in humeral head varus collapse between the 3 suture constructs. CONCLUSIONS: In our biomechanical evaluation of a simulated osteoporotic 2-part proximal humerus fracture with incompetent medial calcar, tension-relieving sutures placed between a lateral locked plate and the rotator cuff tendons prevented varus malalignment.

Nail diameter significantly impacts stability in combined plate-nail constructs used for fixation of supracondylar distal femur fractures.

OBJECTIVES: Plate-nail (PN) combinations have been described for fixation of supracondylar distal femur fractures. Small diameter retrograde intramedullary nails (rIMN) are commonly used. The purpose of this study was to investigate the effect of nail diameter on construct stability. We hypothesized that a larger diameter rIMN would not significantly change the stiffness of the PN construct when tested in torsional or axial loading. METHODS: Twelve synthetic osteoporotic femurs were used to compare nail diameters in an extraarticular supracondylar distal femur fracture model (Orthopaedic Trauma Association/Arbeitsgemeinschaft für Osteosynthesefragen type 33-A3). Constructs were fixed with a 12-hole 4.5 mm pre-contoured lateral distal femoral locking plate combined with either a 9 mm (n = 6) or an 11 mm (n = 6) retrograde intramedullary nail (rIMN). Specimens were cyclically loaded in torsion and axial compression. The primary outcome was construct stiffness, calculated using the average slope of the force-displacement curves. RESULTS: The 11 mm PN construct was approximately 1.6 times stiffer than the 9 mm PN construct averaged across all torsional loads (2.39 +/- 0.41 Nm/deg vs 1.44 +/- 0.17 Nm/deg) and approximately 1.3 times stiffer than the 9 mm PN construct averaged across all axial loads (506.84 +/- 44.50 N/mm vs 376.77 +/- 37.65 N/mm). There were no construct failures. CONCLUSIONS: In this biomechanical model, nail diameter had a significant effect on both torsional and axial stiffness in PN constructs. While the use of smaller diameter rIMNs has been proposed to allow for easier placement of implants, the effect on overall construct stiffness should be considered in the context of the patient, their fracture and desired postoperative weight bearing recommendations.Level of Evidence: N/A.

Cannabis Exposure Decreases Need for Blood Pressure Support During General Anesthesia in Orthopedic Trauma Surgery.

Introduction: As cannabis use continues to increase in popularity, it is important to investigate how it impacts public health in all sectors of the population, including patients undergoing anesthetic management. This retrospective study focuses on the orthopedic trauma population presenting through an emergency department (ED) and receiving a urine drug screen (UDS) with subsequent urgent surgical intervention. We aimed to evaluate differences in response to general anesthesia in patients with exposure to THC, a major cannabinoid, compared to controls that screened negative for THC. Materials and Methods: All ED visits at UC Irvine, a level 1 trauma center between November 4, 2017 and January 7, 2020, were evaluated in this study. Only adult patients who received a UDS and underwent urgent orthopedic trauma surgery within 48 h of ED visit were included in this study. Additional inclusion criteria required an anesthesia time greater than 1 h as well as anesthesia induction and intubation while in the operating room. Overall, we analyzed a total of 221 adult patients. Discussion: When adjusting for demographic variability, there were statistically significant differences in response to general anesthesia between these two groups. The THC-positive (THC(+)) group was less likely to receive intraoperative vasopressors, had higher mean arterial blood pressure and mean diastolic blood pressure, needed less total fluid input and had a lower overall fluid balance. Chronic exposure to THC has been shown to downregulate cannabinoid 1 receptors and cause alterations in endocannabinoid tone. These are two potential mechanisms by which the THC(+) group in our study may have become more resistant to the typically observed hypotensive effects of general anesthesia. Conclusion: The present study suggests that prior use of cannabis, objectively assessed by urinalysis, results in a decreased need for blood pressure support during general anesthesia. The physiological basis for this phenomenon is unclear, but possible causes might include the downregulation of vascular cannabinoid receptor 1 and/or altered endocannabinoid levels after exposure to cannabis.

Fixation of Extra-articular Proximal Tibia Fractures: Biomechanical Comparison of Single and Dual Implant Constructs.

OBJECTIVES: This biomechanical study seeks to define the relative effectiveness of contemporary single and dual implant constructs for fixation of an extra-articular proximal tibia fracture model. METHODS: An extra-articular proximal tibia fracture model was created using synthetic tibias. Four constructs were tested. Constructs included (1) lateral locked plate (LLP), (2) intramedullary nail (IMN), (3) combined LLP and IMN (PN), and (4) LLP and medial locked plate. Specimens were axially loaded through the medial plateau to evaluate construct stiffness and the ability to resist varus collapse. RESULTS: Dual implant constructs were stiffer than single implant constructs in this model. Although DP and PN were stiffer than IMN at all loads tested, the difference was notable only for DP at higher loads. Isolated LLP provided insufficient stability to be tested at higher loads. CONCLUSION: Dual plate fixation provides the greatest resistance to varus collapse. In the clinical setting, consideration must be given to the fracture morphology, desired construct stiffness, and soft-tissue envelope in selecting the optimal construct to be used.

Technical considerations for the management of segmental osseous defects with an internal bone transport nail.

INTRODUCTION: Traditionally, distraction osteogenesis has been accomplished with an external fixator. All internal transport utilizing magnetic intramedullary nails is a newer technique for bone reconstruction. The Precice Bone Transport Nail is a new implant that allows for noninvasive transport via a magnetically driven motor. AREAS COVERED: This report describes the function of the Bone Transport Nail along with the technical considerations on how to successfully manage bone defects with this new technology. Appropriate use of the nail, preoperative planning, intraoperative considerations, and postoperative management are discussed in detail. EXPERT OPINION: The Precice Bone Transport Nail utilizes the technology of the original Precice nail to provide an all-internal option for reconstruction of intercalary defects. This obviates the need for an additional plate with a standard Precice nail when performing bone transport and allows for a less invasive option that decreases operating room time. It provides a more cosmetic result than external fixation and avoids the risks of pin tract infection. Preoperative planning is essential to appropriate execution of the operative procedure and to perform a successful transport. A thorough understanding of the nail design and limitations are a prerequisite as this implant is significantly different from a standard intramedullary nail.

Muscular Forces Responsible for Proximal Humeral Deformity After Fracture.

OBJECTIVES: To evaluate the contribution of each of the rotator cuff muscles and deltoid to fracture deformity in a 2-part proximal humerus fracture model. Our hypothesis was that superior cuff muscles would have the greatest contribution to coronal plane deformity, whereas muscles with anterior and posterior attachments would have the greatest contribution to axial and sagittal plane deformity. METHODS: A medial wedge osteotomy was created in 8 cadaveric shoulder specimens. A custom shoulder testing system was used to load each rotator cuff muscle and deltoid under increasing loading conditions. Fracture displacement was measured using a Microscribe digitizing system. The primary outcome was the contribution of each muscle to varus collapse. Secondary outcomes included contributions of each muscle to apex anterior/posterior deformity and humeral head anteversion/retroversion. RESULTS: Unbalanced loading of the supraspinatus resulted in the greatest varus deformity (34.5 ± 2.3 degrees), followed by the infraspinatus (22.3 ± 3.6 degrees) and subscapularis (21.7 ± 3.1 degree) (P < 0.05). Unbalanced loading of the subscapularis induced the greatest apex posterior (27.5 ± 4.8 degrees, P < 0.05) and retroversion (39.0 ± 5.6 degrees, P < 0.05) deformity, whereas the infraspinatus induced the greatest apex anterior (8.7 ± 3.4 degrees, P > 0.05) and anteversion (17.7 ± 5.7 degrees, P > 0.05) deformity. CONCLUSIONS: In this proximal humerus fracture model, the supraspinatus was the primary driver of varus deformity, whereas the subscapularis and infraspinatus contributed to apex posterior/retroversion and apex anterior/anteversion, respectively. The subscapularis and infraspinatus are also important secondary drivers of varus deformity. This study establishes a physiologically relevant fracture model that mimics in vivo conditions for future biomechanical testing.