Aims

The use of high tibial osteotomy (HTO) to delay total knee arthroplasty (TKA) in young patients with osteoarthritis (OA) and constitutional deformity remains debated. The aim of this study was to compare the long-term outcomes of TKA after HTO compared to TKA without HTO, using the time from the index OA surgery as reference (HTO for the study group, TKA for the control group).

It is unclear why ACL rupture increases osteoarthritis risk, regardless of ACL reconstruction. Our aims were: 1) to establish the reliability and accuracy of a direct method of determining tibiofemoral contact in vivo with UO-MRI, 2) to assess differences in knees with ACL rupture treated nonoperatively versus operatively, and 3) to assess differences in knees with ACL rupture versus healthy knees.

We recruited a convenience sample of patients with prior ACL rupture. Inclusion criteria were: 1) adult participants between 18–50 years old; 2) unilateral, isolated ACL rupture within the last five years; 3) if reconstructed, done within one year from injury; 4) intact cartilage; and 5) completed a graduated rehabilitation program culminating in return to sport or recreational activities. Participants were excluded if they had other ligament ruptures, osteoarthritis, an incompletely rehabilitated injury, were prohibited from undergoing MRI, or had a history of ACL re-rupture. Using the UO-MRI, we investigated tibiofemoral contact area, centroid location, and six degrees of freedom alignment under standing, weightbearing conditions with knees extended. We compared patients with ACL rupture treated nonoperatively versus operatively, and ACL ruptured knees versus healthy control knees. We assessed reliability using the intra-class correlation coefficient, and accuracy by comparing UO-MRI contact area with a 7Tesla MRI reference standard. We used linear mixed-effects models to test the effects of ACL rupture and ACL reconstruction on contact area. We used a paired t test for centroid location and alignment differences in ACL ruptured knees versus control knees, and the independent t test for differences between ACL reconstruction and no reconstruction. Analyses were performed using R version 3.5.1. We calculated sample size based on a previous study that showed a contact area standard deviation of 13.6mm2, therefore we needed eight or more knees per group to detect a minimum contact area change of 20mm2with 80% power and an α of 0.05.

We recruited 18 participants with ACL rupture: eight treated conservatively and 10 treated with ACL reconstruction. There were no significant differences between the operative and nonoperative ACL groups in terms of age, gender, BMI, time since injury, or functional knee scores (IKDC and KOOS). The UO-MRI demonstrated excellent inter-rater, test-retest, and intra-rater reliability with ICCs for contact area and centroid location ranging from 0.83–1.00. Contact area measurement was accurate to within 5% measurement error. At a mean 2.7 years after injury, we found that ACL rupture was associated with a 10.4% larger medial and lateral compartment contact areas (P=0.001), with the medial centroid located 5.2% more posterior (P=0.001). The tibiae of ACL ruptured knees were 2.3mm more anterior (P=0.003), and 2.6° less externally rotated (P=0.010) relative to the femur, than contralateral control knees. We found no differences between ACL reconstructed and nonreconstructed knees.

ACL rupture was associated with significant mechanical changes 2.7 years out from injury, which ACL reconstruction did not restore. These findings may partially explain the equivalent risk of post-traumatic osteoarthritis in patients treated operatively and nonoperatively after ACL rupture.

Purpose of the study and background

An integrated rehabilitation programme was developed and found feasible taking into account the existing evidence base, appropriate theories, and patient and public involvement. The integrated programme encompasses inpatient activities supported by a multidisciplinary team, and integration of knowledge, skills and behaviours in the patient's everyday life. The aim of this trial was to compare the effectiveness of an integrated rehabilitation programme with an existing rehabilitation programme in patients with chronic low back pain (CLBP).

Purpose: Locked plating has become a commonly used technique in complex fracture and nonunion work. The combination of locked and unlocked screws in the same construct has been referred to as “hybrid” fixation. Little work is available to direct the specifics of this fixation method. The purpose of this study was to determine the relative contribution of the number and location of locked screws on the properties of hybrid plate constructs in an osteoporotic bone model.

Method: A prefabricated osteoporotic model was used for reproducibility (composite cylinders 35 mm in diameter and consisting of a 2.5 mm fiberglass shell filled with 10 lb/ft3 polyurethane). A 5mm gap model was used, and fixed with a 12 hole plate. Six different constructs were tested including 2 unlocked and 4 hybrid configurations. All screws were bicortical and placed with 4Nm of torque. Baseline removal (loosening) torque was recorded for each screw for comparison with removal torque after cyclic loading. Testing was performed with ±8Nm of torsional load and run to 100,000 cycles. Stiffness of each construct was measured at 10,000 cycle increments and the removal torque of each screw was recorded at the conclusion of the 100,000 cycles.

Results: Stiffness of the constructs was most affected by the number of screws. No effect was seen with the replacement of one or two unlocked screws with locked screws on each side of the gap. Replacement of three unlocked screws with locked screws increased the stiffness of the construct (p< 0.001).

Conclusion: At least three bicortical locked screws on each side of a construct are needed to increase the stiffness and decrease the loss of stiffness over 100,000 cycles of torsional stress in an osteoporotic surrogate model. Locked screws placed between the fracture and unlocked screws protect the unlocked screws from loosening and may have some clinical utility in fatigue of the construct.

Unlike metal-on-Polyethylene, metal-on-metal (MoM) implants seem to affect the adaptive immune response as evident from the associated perivascular infiltrate containing lymphocytes and plasma cells. This is more pronounced in implant failure secondary to aseptic loosening, and may represent the failure mode. A reduction in CD8+ T lymphocyte counts has also been described with Hip Resurfacing. MoM articulations produce a much smaller order of size of wear particles (nanoparticles) than metal-on- Polyethylene, which may be responsible for the observed adaptive immune system effects. We therefore analyzed the effects of CoCr nanoparticles (CoCrNP) on Dendritic Cells, T cells & B cells.

We produced CoCrNP using repetitive short spark discharges between electrodes of prosthetic CoCr alloy. Electron micrography and Brunauer-Emmet-Teller method both confirmed nanoparticle size. The following experiments were then undertaken.

Dendritic Cells were cultured from mouse bone marrow and incubated with CoCrNP of varying concentrations for 24hrs, or lipopolysaccharide as a positive control. Activation status was then characterized by CD40 expression on fluorescence activated cell sorting (FACS) analysis.

We found CoCrNP did not significantly increase CD40 expression on DCs, neither did it alter CD40 or CD86 expression on B cells. Using a sublethal concentration of CoCrNP as determined from the viability tests, CoCrNP inhibited CD3 & CD3/CD28 dependent T-cell proliferation. This would indicate CoCrNP reduces T cell proliferation and/or survival, which may explain the observed reduction in CD8+ count with hip resurfacing. Understanding the development of the Peri-vascular infiltrate associated with MoM implants will however, probably require more complex (most likely in vivo) models.

Introduction: Metal on Metal articulations produce Cobalt Chromium nanoparticles (CoCrNP) which seems to affect the adaptive immune system, as evident from the perivascular infiltrate of lymphocytes & plasma cells found around some implants, and the reduced CD8+ count described with hip resurfacing. We therefore analyzed effects of CoCrNP on Dendritic Cells, T cells & B cells.

Methods: CoCrNP were produced by repetitive short spark discharges between electrodes of prosthetic CoCr alloy. Electron micrography & BET both confirmed nanoparticle size.

Dendritic Cells were cultured from mouse bone marrow and incubated with CoCrNP of varying concentrations, for 24hrs, or lipopolysaccharide as a positive control. Activation status was then characterized by CD40 expression on FACS analysis.

Results: CoCrNP did not significantly increase CD 40 expression on DCs or Cd 40/ Cd 86 expression on B cells. At subletal concentrations, CoCrNP inhibited ∝CD3 & ∝CD28 dependent T-cell proliferation.

Discussion: CoCrNP reduces both signal 1 & signal 2 dependent T cell proliferation, which may explain the observed reduction in CD 8+ count with hip resurfacing.