Impact of Prophylactic Cerclage Location on Femoral Fracture Propagation: A Biomechanical Study.

OBJECTIVES: Prophylactic cerclage cables are often placed intraoperatively about a fracture to prevent propagation. However, biomechanical data supporting optimal cable placement location are lacking. The objective of this study was to evaluate the impact of prophylactic cerclage placement location on the propagation of femoral shaft fractures. METHODS: The diaphysis of 14 fresh-frozen cadaveric femora were included. Volumetric bone mineral density in the femoral shaft was obtained from quantitative computed tomography scans. For each specimen, a 5-mm longitudinal fracture was created proximally to simulate a pre-existing fracture. After reaming of the femoral canal, a 3 degrees tapered wedge was advanced with an MTS machine at 0.2 mm/s until failure. The tests were conducted with a CoCr cable placed at varying distances (5 mm, 10 mm, 15 mm, 20 mm, and cableless) from the distal tip of the initial fracture. A compression loadcell was used to measure the cable tension during the tests. The axial force, displacement, and cable tension were monitored for comparison between groups. RESULTS: In the cableless group, the mean force needed to propagate the fracture was 1017.8 ± 450.3 N. With the addition of a cable at 5 mm below the fracture, the failure force nearly doubled to 1970.4 ± 801.1 N (P < 0.001). This also led to significant increases in stiffness (P = 0.006) and total work (P = 0.001) when compared with the control group. By contrast, in the 15 and 20 mm groups, there were no significant changes in the failure force, stiffness, and total work as compared with the control group (P > 0.05). CONCLUSIONS: Propagation of femoral shaft fracture was effectively resisted when a prophylactic cable was placed within 5 mm from the initial fracture, whereas cables placed more than 10 mm below the initial fracture were not effective in preventing fracture propagation.

The Stability of Fixation of Vancouver B2 Periprosthetic Femoral Fractures: Effect of Implantation Technique.

BACKGROUND: Due to increasing volume of total hip arthroplasties, periprosthetic femoral fractures have become a common complication with increased revision burden and perioperative morbidity. The objective of this study was to evaluate the fixation stability of Vancouver B2 fractures treated with 2 techniques. METHODS: A common B2 fracture was created by reviewing 30 type B2 cases. The fracture was then reproduced in 7 pairs of cadaveric femora. The specimens were divided into 2 groups. In Group I ("reduce-first"), the fragments were reduced first, followed by implantation of a tapered fluted stem. In Group II ("ream-first"), the stem was implanted in the distal femur first, followed by fragment reduction and fixation. Each specimen was loaded in a multiaxial testing frame with 70% of peak load during walking. A motion capture system was used to track the motion of the stem and fragments. RESULTS: The average stem diameter in Group II was 16.1 ± 0.4 mm, versus 15.4 ± 0.5 mm in Group I. The fixation stability was not significantly different in the 2 groups. After the testing, the average stem subsidence was 0.36 ± 0.31 mm and 0.19 ± 0.14 mm (P = .17) and the average rotation was 1.67 ± 1.30° and 0.91 ± 1.11° (P = .16) in Groups I and II, respectively. Compared to the stem, there was less motion of the fragments and there was no difference between the 2 groups (P > .05). CONCLUSIONS: When tapered fluted stems were used in combination with cerclage cables for treatment of Vancouver type B2 periprosthetic femoral fractures, both the "reduce-first" and "ream-first" techniques showed adequate stem and fracture stability.

The Length of Diaphyseal Contact of Tapered Fluted Stems is Highly Dependent on Canal Morphology.

BACKGROUND: Diaphyseal fixation remains the mainstay of revision THA. The stability of diaphyseal fixation can be quantified by the extent of contact between the stem and the endosteal cortex. This is highly affected by the morphology of the proximal femur. The purpose of this study was to examine factors affecting diaphyseal contact in the revision THA and to identify preoperative predictors of adequate fixation. METHODS: Three-dimensional femur models were created from CT scans of 33 Dorr B and C femora. The proximal 120 mm of the femur was omitted to mimic proximal bone deficiency. A tapered fluted stem (3 degrees, 150 mm) model was virtually implanted after reaming of the medullary canal. The contact length between stem and endosteal cortex was measured, in addition to other variables. The relationship between variables was evaluated using Spearman's correlation, and logistic regression analysis was used to identify predictors of the contact length (P < .05). RESULTS: The contact length varied widely between specimens (66.5 ± 16.6 mm, range: 21-98 mm). Contact increased with the depth of the isthmus below the lesser trochanter (range: 55-155 mm; r2 = 0.473, P = .005) and the distance between the isthmus and the distal edge of the damage zone (range: -9 to 96 mm; r2 = 0.508, P = .002). Stepwise regression identified the reaming length, distance between fracture and the isthmus, and isthmus diameter as independent predictors of contact length (r = 0.643). CONCLUSIONS: Contact is limited in specimens where the isthmus is more proximally located. In these cases, supplementary fixation using plating and/or longer, curved prosthesis may be considered.

The association of anaemia and its severity with composite morbidity after total hip arthroplasty.

BACKGROUND: Total hip arthroplasty (THA) is a common orthopaedic procedure and is expected to increase with an increasing elderly population. Many of these patients suffer from chronic diseases which might be associated with anaemia. Anaemia, by itself, increases the risk of morbidity. We aimed to delineate relationship between preoperative anaemia and postoperative composite morbidities in patients undergoing primary THA. METHODS: A cohort study analysed the data from the American College of Surgeons National Surgical Quality Improvement Program 2008-2014 database. Adult patients who underwent unilateral primary THA were included and divided into 3 groups: no anaemia, mild anaemia, and moderate-to-severe anaemia. Thirty-day mortality and morbidity were recorded as adverse events. The associations between anaemia, baseline characteristics, and adverse events were analysed after adjusting for confounders. RESULTS: Moderate-to-severe anaemia patients were at increased risk for composite morbidity (adjusted odds ratio, 1.43 [1.17-1.74]) when compared to non-anaemics. The stratification revealed a significant effect of younger age, male gender, white race, obesity, general anaesthesia, and mean operative time >120 minutes in patients with moderate-to-severe anaemia. These patients were also at a higher risk of developing several specific morbidities. CONCLUSION: Moderate-to-severe anaemia increases the risk for composite morbidities, but not mortality in patients undergoing primary THA. Further studies are needed to assess whether preoperative management of moderate-to-severe anaemia would improve outcomes in patients undergoing THA.

Editorial Commentary: Will Suture Tape Augmentation Prove to Be the Answer to Anterior Cruciate Ligament Graft Remodeling, Ultimate Strength, and Safe Return to Play?

Anterior cruciate ligament graft augmentation may protect the graft during the early phases of graft remodeling. A concern is stress-shielding, and recent time-zero biomechanical models are promising in this regard. To get the best answer, it will require in vivo healing studies conducted in animals, and eventually human studies using non-invasive imaging techniques, and ultimately clinical outcome studies including evaluation of return to play in athletes. For now, until additional research studies are available, this type of augmentation is best reserved as an option in carefully selected patients with a small graft size at the time of harvest.