Indications for Nonbiological Reconstruction of Posttraumatic Bone Defects About the Knee.

SUMMARY: 3D printing and modeling has continued to grow in popularity over the past decade because the technology has matured and become more affordable and widely available. The main indications for nonbiological reconstruction of large bone defects are principally those patients where the candidate is unlikely to be successful if reconstructed by other means. Bespoke, custom, patient-specific implants can be designed to very effectively address bone loss, incorporating design elements that are particular to the needs of any given unique clinical condition. These implants are generally designed as titanium scaffolds that encourage bony incorporation at the host implant junction both proximal and distal. These scaffolds are typically considered a cellular solid, with high porosity that also promotes bone ingrowth directly into the substance of the body of the implant. Titanium scaffolds of this type have become a useful treatment alternative for large segmental bone defects around the knee, especially distal femoral defects. These are often adult patients with local or systemic compromise, or instead they may be too young to be considered candidates for reconstruction using a megaprosthesis. The process requires careful evaluation of individual patients, then matching that patient with the best treatment option, while recognizing the expectations and demands specific to that particular patient. Several cases are presented here to illustrate the variety of indications that can be successfully addressed with this technology, highlighting the quality of the clinical outcome that can be achieved despite the complexity of the pathology encountered.

A Suprapatellar Approach, When Compared With an Infrapatellar Approach, Yields Less Anterior Knee Pain and Better Patellofemoral Joint Function, for Intramedullary Nailing of Diaphyseal Tibial Fractures: Results of a Randomized Controlled Trial.

OBJECTIVES: To assess if a suprapatellar (SP) approach, when compared with an infrapatellar (IP) approach, yielded less patient-reported anterior knee pain and higher patellofemoral joint function at 6 weeks and 12 months postoperatively, when treating tibial fractures with intramedullary nailing. DESIGN: Prospective, parallel-group randomized control trial. SETTING: Tertiary level 1 trauma care center, Brisbane, Australia. PATIENTS SELECTION CRITERIA: Skeletally mature patients with an acute diaphyseal tibial fracture (AO/OTA 41A2/3, 42 A1-43A3) amenable to an intramedullary nailing were included. Exclusion criteria were periprosthetic fractures, nonunions, and presence of a contralateral injury that would restrict weight-bearing. OUTCOME MEASURES AND COMPARISONS: Anterior knee pain through the visual analog scale (VAS) and patellofemoral function using the Kujala scale at 6 weeks and 12 months were compared between those treated with a SP and IP approach. RESULTS: Ninety-five tibia fractures were included in the randomized trial, with complete follow-up data for 44 and 46 tibia fractures in the SP and IP groups, respectively. The SP cohort exhibited better patellofemoral knee function at both 6 weeks (Kajula 53.0 for SP vs. 43.2 for IP, P < 0.01) and 12 months (Kujala 92.0 for SP vs. 81.3 for IP, P < 0.01) postoperatively and a reduction in anterior knee pain at 12 months postoperatively (VAS 0.7 SP vs. 2.9 IP, P < 0.01). CONCLUSIONS: This randomized trial demonstrated clinically meaningful differences in patellofemoral function, for a SP versus IP approach, with a greater than 10 point discrepancy in Kujala score at both 6 weeks and 12 months. In addition, there was a clinically important difference in VAS knee pain scores for patients at 12 months, but not at 6 weeks, postoperatively. These results contribute to the growing body of evidence demonstrating the functional and clinical benefits of the SP approach. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Classification of Bone Defects: An Extension of the Orthopaedic Trauma Association Open Fracture Classification.

OBJECTIVES: To develop a post-traumatic bone defect classification scheme and complete a preliminary assessment of its reliability. DESIGN: Retrospective classification. SETTING: Tertiary referral trauma center. PATIENTS/PARTICIPANTS: Twenty open fractures with bone loss. INTERVENTION: Assignment of a bone defect classification grade. MAIN OUTCOME MEASUREMENTS: Open fractures were classified based on orthogonal radiographs, assessing the extent and local geometry of bone loss, including D1-incomplete defects, D2-minor/subcritical (complete) defects (<2 cm), and D3-segmental/critical-sized defects (≥2 cm). Incomplete defects (D1) include D1A-<25% cortical loss, D1B-25%-75% cortical loss, and D1C->75% cortical loss. Minor/subcritical (complete) defects (<2 cm) (D2) include D2A-2 oblique ends allowing for possible overlap, D2B-one end oblique/one end transverse, and D2C-2 transverse ends. Segmental/critical-sized Defects (≥2 cm) include D3A-moderate defects, 2 to <4 cm; D3B-major defects, 4 to <8 cm; and D3C-massive defects, ≥8 cm. Reliability was assessed among 3 independent observers using Fleiss' kappa tests. RESULTS: Interobserver reliability demonstrated the classification scheme has very good agreement, κ = 0.8371, P < 0.0005. Intraobserver reliability was excellent, κ = 1.000 (standard error 0.1478-0.1634), P < 0.00001. Interobserver reliability for the distinction between categories alone (D1, D2, or D3) was also excellent, κ = 1.000 (standard error 0.1421-0.1679), P < 0.00001. CONCLUSIONS: This classification scheme provides a robust guide to bone defect assessment that can potentially facilitate selection of the most appropriate treatment strategy to optimize clinical outcomes.

Combined Technique for the Treatment of Infected Nonunions of the Distal Femur With Bone Loss: Short Supracondylar Nail-Augmented Acute Shortening/Lengthening.

OBJECTIVE: To evaluate a combined technique for treating distal femoral bone defects after debridement of osteomyelitis, using an external fixator together with a short supracondylar nail. DESIGN: Retrospective study. SETTING: Single tertiary referral center. METHODS: Between 2003 and 2018, 23 patients with a mean age of 37.2 years (26-56) underwent surgery with the same technique to manage postdebridement defects in the distal femur due to osteomyelitis. This involved acute shortening and intramedullary fixation of the defect site, together with relengthening from a proximal osteotomy using simultaneous external fixation. Radiographic union, range of motion of the hip and knee, external fixation time and external fixation index, and limb length discrepancy were assessed. RESULTS: The mean follow-up was 51 months (18-192). Union was achieved in all patients without recurrence of infection during this follow-up period. The mean knee flexion was 120 degrees, and the mean extension deficit was 5 degrees at final follow-up. The mean limb length discrepancy improved from 5.5 cm (3-7) to 0.5 cm (0-2). The mean external fixation index was 29.2 d/cm (20-50), and the mean external fixation time was 115 days (90-150). Radiographic scores were excellent in 15 cases, good in 6, and fair in 2. Functional scores were excellent in 14 cases, good in 7, and fair in 2. CONCLUSION: This combined strategy was an effective method for treating distal femoral segmental bone defects after debridement of osteomyelitis, with a high rate of union and acceptable complication rates. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

An articulated antibiotic spacer used for infected total knee arthroplasty: a comparative in vitro elution study of Simplex and Palacos bone cements.

For the staged management of infected total knee arthroplasty (TKA), antibiotic laden polymethylmethacrylate (PMMA) spacers have been recommended. Antibiotic-impregnated PMMA spacers target drug delivery, achieving high local levels while limiting the potential for host toxicity associated with parenteral antimicrobial therapy. This study examined the elution characteristics of an articulating PMMA TKA spacer that has been useful clinically. Tobramycin and vancomycin are both active against many organisms leading to joint infections. We used various combined antibiotic concentrations (maintaining a relative ratio of 55% tobramycin to 45% vancomycin w/w), and then assayed the elution profile of the TKA spacer in vitro. Additionally, the elution qualities of two brands of bone cement, Simplex and Palacos, were compared. Briefly, three groups of PMMA spacers, impregnated with different antibiotic loads, were fashioned from a mold replicating a femoral TKA component. The entire spacer surface area was immersed in sterile phosphate buffered saline (PBS) in a 1:6 ratio of grams of cement to milliliters of PBS and incubated at 37 degrees C for 24 h. After 24 h, aliquot eluates were taken, the PBS discarded, and replaced with fresh, sterile PBS. PBS was changed daily and an aliquot was taken at least weekly for nine weeks. Eluate samples were stored at -70 degrees C until assayed. Each spacer eluate sample's antibiotic concentration was determined by disc diffusion bioassay against Bacillus subtilis. Mean zone inhibition diameters were extrapolated from the standard curve to yield micrograms per milliliter of antibiotic in PBS. In all groups the Palacos spacers demonstrated higher elution levels, above the MIC for the organism used, for a longer period of time than those made with Simplex. Based on the observed elution profiles, antibiotic-impregnated Palacos bone cement may offer a more effective vehicle for local drug delivery during staged treatment of infected TKA.

Musculoskeletal sepsis: principles of treatment.

Musculoskeletal sepsis is infection of bone, joints, muscles, and skin and often occurs after open fractures. Thus, the main objective in the treatment of open fractures in restoration of function and prevention of infection. It is important to consider all open fracture wounds as contaminated. The principles of open fracture treatment include taking appropriate cultures, instituting immediate systemic antibiotic therapy, surgical débridement and wound management, stabilizing the fracture, and early bone grafting when indicated. The open tibial fracture, classified according to Gustilo and Anderson, serves as an exemplary model for musculoskeletal sepsis because this type of injury is described extensively in the literature. Early diagnosis and effective surgical and antibiotic management can control musculoskeletal sepsis, and the suppression of infection may last a lifetime.