Variability in stem taper surface topography affects the degree of corrosion and fretting in total hip arthroplasty.

Degradation at the modular head-neck interface in total hip arthroplasty (THA) is predominately expressed in the form of corrosion and fretting, potentially causing peri-prosthetic failure by adverse reactions to metal debris. This retrieval study aimed to quantify variations in stem taper surface topographies and to assess the influence on the formation of corrosion and/or fretting in titanium alloy stem tapers combined with metal and ceramic heads. Four hip stem designs (Alloclassic, CLS, Bicontact and SL-Plus) were characterized using high-resolution 3D microscopy, and corrosion and fretting were rated using the Goldberg scoring scheme. Quantification of the taper surface topographies revealed a high variability in surface characteristics between threaded stem tapers: Alloclassic and CLS tapers feature deeply threaded trapezoid-shaped profiles with thread heights over 65 µm. The sawtooth-shaped Bicontact and triangular SL-Plus taper are characterized by low thread heights below 14 µm. Significantly lower corrosion and fretting scores were observed in lightly threaded compared to deeply threaded tapers in ceramic head combinations. No significant differences in corrosion or fretting scores with thread height were found in pairings with metal heads. Understanding the relationship between stem taper surface topography and the formation of corrosion and fretting could help to improve the performance of modern THAs and lead to longer-lasting clinical results.

Elevated HbA1c is not a risk factor for wound complications following total joint arthroplasty: a prospective study.

BACKGROUND: Controversies exist regarding the association of elevated serum glycated haemoglobin (HbA1c) levels and postoperative surgical site infection (SSI) or prosthetic joint infection (PJI) in the setting of total hip and knee arthroplasty (THA and TKA). The purpose of the current study was to determine the prevalence of unknown and uncontrolled diabetes mellitus (DM) in a consecutive series and to investigate the association between postoperative wound complications or SSI/PJI and elevated HbA1c in patients undergoing TJA. METHODS: In this prospective single-centre study, HbA1c was determined for patients undergoing elective primary, aseptic or septic revision THA and TKA, between September 2017 and March 2018. Prevalence of DM, unknown and uncontrolled diabetes were reported. Occurrence of 90-day wound healing disorders (WHD) as well as SSI or PJI were observed. Considering the HbA1c threshold ⩾6.5%, a comparative analysis between patients with and without WHD and SSI or PJI for the whole study cohort, as well as for each arthroplasty group, was performed. Receiver operating characteristic (ROC) curves were developed to quantify the predictive power of HbA1c with regard to WHD and infection complications. A total of 1488 patients were included for final analysis. There were 1127 primary THA and TKA (75.7%), 272 aseptic revisions (18.3%) and 89 septic revisions (6.0%). The known diabetic patients constituted 9.9% of the whole study cohort. RESULTS: The majority had uncontrolled DM (67%). Prevalence of unknown DM was 11.1%. The results reveal the prevalence for the German population and might be different in other regions. A total of 57 patients (3.7%) experienced postoperative wound or infectious complications. PJI occurred in only 5 patients (0.03%). There was no significant difference between patients with HbA1c <6.5% and patients with HbA1c ⩾6.5% (p = 0.092). CONCLUSIONS: We demonstrated that prevalence of unknown and uncontrolled DM in patients undergoing TJA is increasing, however; routine preoperative determination of the HbA1c value to prevent possible postoperative wound or infectious complications remains debatable. Larger studies investigating the optimal HbA1c level, as well as other predictors are required.

Multiscale bone quality analysis in osteoarthritic knee joints reveal a role of the mechanosensory osteocyte network in osteophytes.

Osteophytes - bony outgrowths on joint structures - are found in healthy individuals but are specifically present in late osteoarthritis (OA). Osteophyte development and function is not well understood, yet biomechanical stimuli are thought to be critical. Bone adapts to mechanical forces via the cellular network of osteocytes. The involvement of osteocytes in osteophyte formation and maturation has not been unravelled. Forty-three osteophytes from tibias of 23 OA patients (65 ± 9 years) were analysed. The trabecular bone structure of osteophytes presented with fewer trabeculae of lower bone mineral density compared to subchondral bone. We identified 40% early stage and 60% late stage osteophytes that significantly differed in their trabecular bone characteristics. Osteophyte bone revealed a higher number of osteocytes and a lower number of empty osteocyte lacunae per bone area than the subchondral bone. We found that OA osteophytes consist of younger bone material comprised of woven and lamellar bone with the capacity to develop into a late stage osteophyte potentially via the involvement of the osteocyte network. Our analysis of OA osteophytes implies a transition from woven to lamellar bone as in physiological bone growth within a pathological joint. Therefore, osteophyte development and growth present a valuable research subject when aiming to investigate the osteogenic signalling cascade.

Limitations in molecular detection of lymph node micrometastasis from colorectal cancer.

Colorectal cancer patients with lymph node metastasis have a shorter survival and may require adjuvant therapy after surgery of the primary tumor. It is supposed that a more reliable diagnosis can be achieved using tumor-specific DNA mutations for the detection of metastasizing cells. To design a practical approach for a molecular diagnosis of micrometastasis, we applied direct DNA sequencing to screen 48 early stage colorectal carcinomas for the most frequent mutations of the KRAS, P53, and APC tumor genes. KRAS mutations were detected as frequently as described earlier. In contrast, the frequency of P53 and APC hot spot mutations was unexpectedly low, compared with previous studies using other screening methods or including advanced tumor stages. Not more than 31% of early stage tumors showed a mutation in at least 1 of the selected hot spot codons. Applying mutant-enriched polymerase chain reaction (PCR), the mutation of the primary tumor was detected in lymph node DNA from 2 of the KRAS-positive patients. In 1 patient, the result was not verified by subtractive iterative PCR, a principally different molecular method with high sensitivity and specificity. Our data suggest that screening for suitable markers for a molecular detection of occult lymph node metastasis cannot be restricted to small-sized hot spot regions of a few tumor genes and possibly must include tumor-specific epigenetic changes. Furthermore, restriction enzyme-based methods such as mutant-enriched PCR are not suitable to detect any mutation with equal efficiency and they should be carefully controlled to avoid false-positive detection of marker mutations in lymph node DNA.