The anatomical shape of the distal femur is an independent risk factor for aseptic loosening following one-stage septic knee revision using rotating hinge knee prosthesis.

PURPOSE: Aseptic loosening (AL) is the second most common reason for failure after one-stage septic knee revision. In this context, the goal of the study is to identify risk factors for AL following one-stage septic knee revision using rotating hinge implants. We aimed to answer the following research question: How does the anatomical shape of the distal femur represent an independent risk factor for AL following one-stage septic knee revision arthroplasty? METHODS: Patients, who had undergone re-revision surgery due to AL of the rotating hinge knee prosthesis after one-stage septic knee revision arthroplasty between January 2008 and December 2018, were included. For this purpose, 41 patients with AL after one-stage septic knee revision using rotating hinge implants and 37 controls without any revision surgery at latest follow-up were included in this study. Using standardized anteroposterior (AP) views of the knee in all patients, we measured the inner diameter of the femur 20 cm proximally from the joint line and at a point 2 cm proximally from the adductor tubercle. RESULTS: Among the vast majority of AL cases, we identified an isolated loosening of the femoral component. The AL group showd a high distribution of the Type C according to the Citak classification with 75.7%. Contrary to this, with 24.3% (p < 0.001) the amount of Type C cases was relatively low in the control group. Consequently, Type C configurations of the distal femur represent an independent risk factor for AL with an approximately sevenfold higher risk for AL compareed to Type A and Type B. CONCLUSIONS: The novel radiological classification system of the distal femur shows that the Type C subtype is an independent and main risk factor for AL after one-stage septic knee revision using rotating hinge knee implants.

Twenty-year results of a neck-preserving short-stem prosthesis in primary total hip arthroplasty.

PURPOSE: The use of short-stemmed femoral components with preservation of the femoral neck has been advocated for younger and more active patients undergoing joint replacement. This study reports the long-term outcomes of the Collum Femoris-Preserving (CFP) prosthesis on a previous report. METHODS: Between January 1999 and December 2000, a total of 149 patients underwent total hip arthroplasty procedure using the CFP stem in a single institution. At latest follow-up, 79 patients were available and were included in this study. The mean age of the cohort was 73.4 (range, 44-92 years) with a mean follow-up of 20.7 years (range 20-21). The average age was 52.1 years at index procedure (range, 21-71 years). RESULTS: The Kaplan-Meier survivorship free from revision for any cause at 5, 10 and 20 years was 93.2% (87.8-96.3%), 93.2% (87.8-96.3%) and 83.0% (75.7-88.3%), respectively. At 20 years follow-up, the revision for any cause occurred in 26.6% (21 of 79) of patients. The most common causes for revision surgery were aseptic loosening, dislocation, and polyethylene wear with 6.3% (5 out of 79), respectively. Periprosthetic fracture occurred in four patients (5.1%) followed by periprosthetic joint infection in two patients (2.5%). Revision surgery of the femoral stem was required in four patients (5.1%). There was a statistically significant improvement of the Harris Hip Scores from 53 to 83.7 (range 56-91). CONCLUSION: The long-term outcomes of the CFP stem are excellent, demonstrating a low rate of aseptic loosening with an excellent survivorship within 2 decades.

Enhancing the radiological classification system from the distal femur to the proximal tibia.

OBJECTIVES: This study aims to identify anatomical variants of the proximal tibia shaft and to develop a novel classification system for proximal tibia. PATIENTS AND METHODS: Between October 2019 and April 2020, a total of 200 patients with standard knee anteroposterior radiographs were included in this study. We measured the inner diameter of the tibia 16 cm distally from the tibial plateau and 3 cm distally from the tibial spine. The ratio between these two measurements was applied as the novel index ratio. RESULTS: A total number of 197 patients (100 males and 97 females) with a median age of 68 years (range, 21 to 89 years) were included in the final analysis. According to the 25th and 75th percentiles, three groups were clustered for each sex. A higher distribution of the type B pattern was found in female and male patients. However, type A with a narrow inner diaphyseal diameter was less common in female patients. The median intraobserver reliability for rater 1 was 0.998. The inter-observer reliability was high (intraclass correlation coefficient: 0.998). There was a moderate correlation between the anteroposterior (AP) diameter and height (r=0.568) and a low correlation between the AP diameter and weight (r=0.376). The novel index shows no significant correlation between the index ratio and height (r=0.082), weight (r=0.014) or body mass index (r=-0.038). CONCLUSION: The novel classification presents three different types of tibia for each sex: type C has a wider inner diaphyseal diameter compared to type A with a narrow inner diaphyseal diameter. Type B has the widest distribution among the subjects.

High revision rates following repeat septic revision after failed one-stage exchange for periprosthetic joint infection in total knee arthroplasty.

AIMS: The outcome of repeat septic revision after a failed one-stage exchange for periprosthetic joint infection (PJI) in total knee arthroplasty (TKA) remains unknown. The aim of this study was to report the infection-free and all-cause revision-free survival of repeat septic revision after a failed one-stage exchange, and to determine whether the Musculoskeletal Infection Society (MSIS) stage is associated with subsequent infection-related failure. METHODS: We retrospectively reviewed all repeat septic revision TKAs which were undertaken after a failed one-stage exchange between 2004 and 2017. A total of 33 repeat septic revisions (29 one-stage and four two-stage) met the inclusion criteria. The mean follow-up from repeat septic revision was 68.2 months (8.0 months to 16.1 years). The proportion of patients who had a subsequent infection-related failure and all-cause revision was reported and Kaplan-Meier survival for these endpoints was determined. Patients were categorized according to the MSIS staging system, and the association with subsequent infection was analyzed. RESULTS: At the most recent follow-up, 17 repeat septic revisions (52%) had a subsequent infection-related failure and the five-year infection-free survival was 59% (95% confidence interval (CI) 39 to 74). A total of 19 underwent a subsequent all-cause revision (58%) and the five-year all-cause revision-free survival was 47% (95% CI 28 to 64). The most common indication for the first subsequent aseptic revision was loosening. The MSIS stage of the host status (p = 0.663) and limb status (p = 1.000) were not significantly associated with subsequent infection-related failure. CONCLUSION: Repeat septic revision after a failed one-stage exchange TKA for PJI is associated with a high rate of subsequent infection-related failure and all-cause revision. Patients should be counselled appropriately to manage expectations. The host and limb status according to the MSIS staging system were not associated with subsequent infection-related failure. Cite this article: Bone Joint J 2022;104-B(3):386-393.

Favourable outcomes of repeat one-stage exchange for periprosthetic joint infection of the hip.

AIMS: One-stage exchange for periprosthetic joint infection (PJI) in total hip arthroplasty (THA) is gaining popularity. The outcome for a repeat one-stage revision THA after a failed one-stage exchange for infection remains unknown. The aim of this study was to report the infection-free and all-cause revision-free survival of repeat one-stage exchange, and to investigate the association between the Musculoskeletal Infection Society (MSIS) staging system and further infection-related failure. METHODS: We retrospectively reviewed all repeat one-stage revision THAs performed after failed one-stage exchange THA for infection between January 2008 and December 2016. The final cohort included 32 patients. The mean follow-up after repeat one-stage exchange was 5.3 years (1.2 to 13.0). The patients with a further infection-related failure and/or all-cause revision were reported, and Kaplan-Meier survival for these endpoints determined. Patients were categorized according to the MSIS system, and its association with further infection was analyzed. RESULTS: A total of eight repeat septic revisions (25%) developed a further infection-related failure, and the five-year infection-free survival was 81% (95% confidence interval (CI) 57 to 92). Nine (28%) underwent a further all-cause revision and the five-year all-cause revision-free survival was 74% (95% CI 52 to 88). Neither the MSIS classification of the host status (p = 0.423) nor the limb status (p = 0.366) was significantly associated with further infection-related failure. CONCLUSION: Repeat one-stage exchange for PJI in THA is associated with a favourable five-year infection-free and all-cause revision-free survival. Notably, the rate of infection control is encouraging when compared with the reported rates after repeat two-stage exchange. The results can be used to counsel patients and help clinicians make informed decisions about treatment. With the available number of patients, further infection-related failure was not associated with the MSIS host or limb status. Cite this article: Bone Joint J 2022;104-B(1):27-33.

A novel radiological classification system of the distal femur.

INTRODUCTION: In our previous studies, we were able to identify anatomical differences as a predictor for aseptic loosening following primary and revision surgery with the use of rotating hinge prosthesis. This study was performed to answer following question: can a novel radiological classification system of the distal femur be identified? MATERIALS AND METHODS: A total of 200 patients who received standardized anteroposterior (AP) and lateral views of the knee joint were included in this study. On AP radiographs, we measured the distance between inner diameter of the femur at 20 cm proximally from the knee and at a point 2 cm proximally from the adductor tubercle. The ratio of the inner diameter of the femoral canal at 20 cm proximal of knee joint to the inner diameter of medullary canal at 2 cm proximal of adductor tubercle was used as a novel index ratio. Two observers blindly and independently reviewed the anteroposterior radiographs twice. RESULTS: Three groups of anatomical classification can be constructed for each sex according to the 25th and 75th percentiles. A higher distribution of Type C was found in female patients. The median intra-observer reliability for rater 1 was 0.995 (IQR 0.994-0.997). We had also a high inter-observer reliability with ICC of 0.997 (95% CI 0.996-0.998). CONCLUSIONS: The novel classification presents three different types of the knee joint for male and female patients. Type C has a wider inner diaphyseal diameter compared to Type A with a narrow inner diaphyseal diameter.

Risk factors for mortality following one-stage septic hip arthroplasty - a case-control study.

PURPOSE: Despite good clinical outcomes and a high success rate, there is a comparatively high mortality after one stage septic exchange of total hip arthroplasty. The aim of this study was to identify risk factors for mortality in the hospitalization period after one-stage septic exchange of THA. METHODS: We retrospectively analyzed in our database all patients who had a one-stage septic exchange for periprosthetic infection of THA and died during hospitalization (n = 33). The control group was matched semi-randomly by surgical procedure (n = 121) who did not die during hospitalization. The two groups were analyzed for risk factors such as age, Charlson Comorbidity Index (CCI), and high-/low-virulence bacteria. RESULTS: In the deceased group, 16 patients were female and 17 were male with a mean age at surgery of 73.2 years. In the control group, there were 55 females and 66 males with an average age at surgery of 68.2 years. Comparing the two groups, the deceased group had a significantly higher proportion of liver disease as well as higher rate of pulmonary embolism, apoplexy, and/or myocardial infarction, an increased CCI with an average of 6.5 and advanced age. Further demographic and surgery-related parameters especially high- or low-virulent germs were not identified as risk factors for mortality during the hospitalization period. The binominal logistic regression analysis showed that the probability of an inpatient death following one-stage septic exchange of THA increases by a factor of 3.079, with each additional point of the CCI. CONCLUSION: In conclusion, advanced age and high CCI are the main risk factors for mortality after single-stage septic change of THA. However, high-virulence bacteria have no influence on the mortality during the hospitalization period after one-stage septic exchange of THA.

Septic Failure After One-Stage Exchange for Prosthetic Joint Infection of the Hip: Microbiological Implications.

BACKGROUND: The microbiological implications of septic failure after 1-stage exchange for prosthetic joint infection (PJI) of the hip remain unclear. METHODS: Information was gathered on comorbidities, previous procedures, preoperative and postoperative microbiology results, methods of detection, and antibiotic resistance patterns, for all patients, who developed septic failure after 1-stage exchange for PJI of the hip performed at our institution during 2001-2017. RESULTS: Seventy-seven patients were identified. Septic failure was diagnosed a mean of 1.7 (standard deviation 2.3, range 0-11.8) years later. Although the spectrum of microorganisms was similar to preoperative, in the majority of patients (55%), the initial microorganism(s) was (were) replaced by (a) totally different microorganism(s). Overall, there was a decrease in the number of polymicrobial PJIs. The number of patients with high virulent microorganisms decreased significantly from 52 to 36 (P = .034). The number of PJIs due to gram-negative pathogens remained similar (11 vs 14, P = .491). The number of rifampicin-resistant staphylococci, fluoroquinolone-resistant streptococci, enterococci, and fungi changed from 8 to 15, 0 to 2, 7 to 3, and 1 to 2, respectively, but these changes did not reach statistical significance. CONCLUSION: The majority of reinfections is caused by different infecting bacteria, hence it is essential to perform a new diagnostic workup and not base treatment decisions (solely) on historical cultures. We were furthermore unable to irrefutably prove that, from a microbiological point of view, septic failure after 1-stage exchange comes with increased challenges. Given the time interval to failure, we propose that a longer follow-up of these patients is needed, than previously suggested.

Short-term mortality after primary and revision total joint arthroplasty: a single-center analysis of 103,560 patients.

INTRODUCTION: The demand for total joint arthroplasty (TJA) is increasing worldwide with excellent long-term results. In general, TJA provides several benefits to the patients but also causes possible complications. The aim of our study was to describe trends in mortality after TJA in a high-volume arthroplasty center, and to examine the potential risk factors. METHODS: From 1996 to 2018, a total of 103,560 patients (73,130 primary cases, 30,430 revision cases) underwent a TJA procedure in our institution. Anthropometric parameters, Charlson Comorbidity Index (CCI), pre- and postoperative hemoglobin (Hb), blood loss during surgery, postoperative complication (such as infection, deep vein thrombosis, pulmonary embolism, etc.) and cause of death from all patients who deceased during hospitalization were collected. The short-term mortality rate was analyzed between the primary and the revision groups. RESULTS: The short-term mortality rate within our investigated groups was low with 0.041% in primary THA, 0.299% in revision THA, 0.045% in primary TKA, 0.205% in revision TKA, 0.214% in TSA/RSA, 0.15 % in primary TAA and 0% after TEA. Significant differences were found for preoperative Hb-values in patients undergoing septic revision (10.7 g/dl) compared to patients undergoing aseptic revision (12.8 g/dl) or primary arthroplasty (13.6 g/dl) (p < 0.001). Furthermore, we found significant differences regarding CCI between the groups. The comparison between causes of death (COD) showed a significantly higher number for pulmonary embolisms in the aseptic groups, while septic shock was the leading COD in the septic group and myocardial infarction as COD was found significantly more often after primary TJA. CONCLUSION: This is the largest single-center study presenting the short-term mortality rate following TJA. Consequently, TJA is a safe procedure with a low short-term mortality rate. However, depending on the type of surgery, certain risk factors cannot be eliminated. In order to further reduce the mortality, procedures as such should continue to be performed at specialized centers under standardized conditions.