Aim

The β-lactam penicillin is often used in the treatment of soft tissue infections and osteomyelitis caused by penicillin susceptible Staphylococcus aureus. Oral antibiotic treatment has been shown to be non-inferior to intravenous (IV) therapy when used during the first 6 weeks in complex orthopedic infections (OVIVA trial). However, the use of oral β-lactams in osteomyelitis treatment remains a topic of debate due to low and variable bioavailability. The aim was to assess the time for which the unbound penicillin concentration exceeded targeted minimum inhibitory concentrations (fT>MIC) in cancellous bone and subcutaneous tissue after IV (penicillin G) and oral (penicillin V) treatment in a porcine microdialysis model.

In an attempt to alleviate symptoms of the disease, patients with knee osteoarthrosis (KOA) frequently alter their gait patterns. Understanding the underlying pathomechanics and identifying KOA phenotypes is essential for improving treatments. We aimed to investigate altered kinematics in patients with KOA to identify subgroups.

Sixty-six patients with symptomatic KOA scheduled for total knee arthroplasty and 12 age-matched healthy volunteers with asymptomatic knees were included. We used k-means to separate the patients based on dynamic radiostereometric assessed knee kinematics. Ligament lesions, KOA score, and clinical outcome were assessed by magnetic resonance imaging, radiographs, and patient reported outcome measures, respectively.

We identified four clusters that were supported by clinical characteristics. Compared with the healthy group; The flexion group (n=20): revealed increased flexion, greater adduction, and joint narrowing and consisted primarily of patients with medial KOA. The abduction group (n=17): revealed greater abduction, joint narrowing and included primarily patients with lateral KOA. The anterior draw group (n=10): revealed greater anterior draw, external tibial rotation, lateral tibial shift, adduction, and joint narrowing. This group was composed of patients with medial KOA, some degree of anterior cruciate ligament lesion and the greatest KOA score. The external rotation group (n=19): revealed greater external tibial rotation, lateral tibial shift, adduction, and joint narrowing while no anterior draw was observed. This group included primarily patients with medial collateral and posterior cruciate ligament lesions.

Patients with KOA can, based on their gait patterns, be classified into four subgroups, which relate to their clinical characteristics. The findings add to our understanding of associations between disease pathology characteristics in the knee and the pathomechanics in patients with KOA. A next step is to investigate if patients in the pathomechanic clusters have different outcomes following total knee arthroplasty.

The Pivot-shift test is a clinical test for knee instability for patinets with Anterior cruciate ligament (ACL), however the test has low inter-observer reliability. Dynamic radiostereometry (dRSA) imaging is a highly precise method for objective evaluation of joint kinematics. The purpose of the study was to quantify precise knee kinematics during Pivot-shift test by use of the non-invasive dynamic RSA imaging.

Eight human donor legs with hemipelvis were evaluated. Ligament lesion intervention of the ACL was performed during arthroscopy and anterolateral ligament (ALL) section was performed as a capsular incision. Pivot-shift test examination was recorded with dRSA on ligament intact knees, ACL-deficient knees and ACL+ALL-deficient knees.

A Pivot-shift pattern was identifyable after ligament lesion as a change in tibial posterior drawer velocity from 7.8 mm/s in ligament intact knees, to 30.4 mm/s after ACL lesion, to 35.1 mm/s after combined ACL-ALL lesion. The anterior-posterior drawer excursion increased from 2.8 mm in ligament intact knees, to 7.2 mm after ACL lesion, to 7.6 mm after combined lesion. Furthermore a change in tibial rotation was found, with increasing external rotation at the end of the pivot-shift motion going from intact to ACL+ALL-deficient knees

This experimental study demonstrates the feasibility of RSA to objectively quantify the kinematic instability patterns of the knee during the Pivot-shift test. The dynamic parameters found through RSA displayed the kinematic changes from ACL to combined ACL-ALL ligament lesion.

Patients with advanced stage hallux rigidus from 12 centers in Canada and the UK were randomized (2:1) to treatment with a small (8/10 mm) hydrogel implant (Cartiva) or 1^st MTP arthrodesis. VAS pain scale, validated outcome measures (FAAM sport scale), great toe active dorsiflexion motion, secondary procedures, radiographic assessment and safety parameters were evaluated.

236 patients were initially enrolled, 17 patients withdrew prior to randomization, 17 patients withdrew after randomization and 22 were non-randomized training patients, leaving 152 implant and 50 arthrodesis patients. Standard demographics and baseline outcomes were similar for both groups.

Mean VAS pain scores decreased from 6.8 and 6.9 respectively for the implant and arthrodesis groups from baseline to 1.4 and 0.7 at 24 months. Similarly, the FAAM sports score improved significantly from baseline levels of 37 and 36 to 24 months level of 77 and 82 respectively for the implant and arthrodesis groups. First MTP active dorsiflexion motion improved an average of 4° at 3 months after implant placement and was maintained at 24 months.

Secondary surgeries occurred in 17 (11.2%) implant patients and 6 (12.0%) arthrodesis patients. Fourteen (9.2%) implants were removed and converted to arthrodesis and 6 (12.0%) arthrodesis patients had painful hardware requiring removal. There was no case of implant fragmentation, wear, or bone loss. Analysis of a single composite endpoint utilizing the three primary study outcomes (pain, function, and safety) showed statistical equivalence between the2groups.

Purpose: B2A2-K-NS (B2A) is a synthetic receptor-targeted peptide that appears to amplify the biological response to rhBMP-2. In ectopic sites in vivo, B2A augments bony mineralization when combined with demineralized bone matrix. The purpose of this study was to determine if the synthetic peptide B2A2-K-NS coated on osteoconductive granules (B2A/G) enhances autograft fusion in a rabbit bilateral posterolateral spine fusion model.

Method: Sixty skeletally mature New Zealand White Rabbits weighing 4.5–5.5 kg were entered into the study (IACUC #0511251). A single-level, bilateral posterolateral intertransverse process fusion was performed at L4-L5 with autogenous bone or an osteoconductive granule containing several coating concentrations of B2A. Animals were euthanized at 6 weeks post surgery.

Results: Gross examination of the surrounding soft tissues and grafted area showed no adverse reactions to the osteoconductive granules with or without B2A. Radiographic fusion rates were similar to palpation fusion rates across all groups. When assessed by palpation, animals treated with 300 μg B2A/G had 80% fusion while those treated with 100 μg B2A/G (89%) and 50 μg B2A/G had 78% fusion. Animals receiving 0 μg B2A/G (granules only) had a fusion rate of 33% and autograft only animals had a fusion rate of 63%.

Conclusion: In this model the B2A/G composition appeared to function as a graft enhancer and be more efficacious than autograft alone in this model. B2A peptide has a unique mechanism of action in that although it interacts with receptors for BMP-2, the action is mediated only in the presence of BMP-2 or an osteoinductive event. In this model, the decorticated TP and/or autogenous bone may have provided the necessary signals for B2A. These results suggest that B2A/G should be further investigated to determine mechanistic effects and clinical applications