Perioperative Intravenous Dexamethasone Significantly Reduces Postoperative Opioid Requirement and Nausea After Unilateral Elective Hip Arthroscopy: A Randomized Double-blinded Placebo-controlled Trial.

BACKGROUND: Previous studies have shown that dexamethasone has a positive effect on postoperative pain control, opioid consumption, nausea, and vomiting and length of hospital stay after arthroplasty surgery. PURPOSE/HYPOTHESIS: The purpose of this study was to assess whether adding perioperative dexamethasone to our current pain regimen after hip arthroscopy is more effective than a placebo. It was hypothesized that dexamethasone would reduce postoperative pain, reduce opioid consumption, improve subjective pain and nausea scores, and reduce the number of vomiting events. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: A total of 50 patients requiring unilateral elective hip arthroscopy were randomized to receive intravenous dexamethasone immediately before induction of anesthesia and at 8 am on the first postoperative day (2 ×12 mg) or a placebo (sodium chloride 0.9%). The patient, the surgeons, the treating anesthesiologist, and the involved nursing and physical therapy personnel were blinded to group assignment. The primary outcome was postoperative pain, and secondary outcomes were opioid consumption and nausea scores-assessed using a translated revised version of the American Pain Society Patient Outcome Questionnaire 6 hours postoperatively and on days 1 and 2-and vomiting events. A clinical follow-up was performed 12 weeks postoperatively to assess adverse events. RESULTS: The mean age at inclusion was 29 years in both groups. Postoperative pain levels did not differ significantly in most instances. Opioid requirements during the hospitalization in the dexamethasone group were significantly lower than those in the placebo group (31.96 ± 20.56 mg vs 51.43 ± 38 mg; P = .014). Significantly fewer vomiting events were noted in the dexamethasone group (0.15 ± 0.59 vs 0.65 ± 0.91; P = .034). Descriptive data and surgical parameters did not differ significantly. CONCLUSION: Perioperative intravenous dexamethasone significantly reduced postoperative opioid consumption by 40% without compromising pain level and safety, as no corticosteroid-related side effects were observed. Dexamethasone may be a valuable adjuvant to a multimodal systemic pain regimen after hip arthroscopy. REGISTRATION: NCT04610398 (ClinicalTrials.gov identifier).

Decoding the function of Atg13 phosphorylation reveals a role of Atg11 in bulk autophagy initiation.

Autophagy is initiated by the assembly of multiple autophagy-related proteins that form the phagophore assembly site where autophagosomes are formed. Atg13 is essential early in this process, and a hub of extensive phosphorylation. How these multiple phosphorylations contribute to autophagy initiation, however, is not well understood. Here we comprehensively analyze the role of phosphorylation events on Atg13 during nutrient-rich conditions and nitrogen starvation. We identify and functionally characterize 48 in vivo phosphorylation sites on Atg13. By generating reciprocal mutants, which mimic the dephosphorylated active and phosphorylated inactive state of Atg13, we observe that disrupting the dynamic regulation of Atg13 leads to insufficient or excessive autophagy, which are both detrimental to cell survival. We furthermore demonstrate an involvement of Atg11 in bulk autophagy even during nitrogen starvation, where it contributes together with Atg1 to the multivalency that drives phase separation of the phagophore assembly site. These findings reveal the importance of post-translational regulation on Atg13 early during autophagy initiation, which provides additional layers of regulation to control bulk autophagy activity and integrate cellular signals.

Gluteus maximus tendon transfer as a salvage option for painful chronic hip abductor insufficiency: clinical and MRI results with a minimum follow-up of 24 months.

INTRODUCTION: Chronic hip abductor insufficiency is a rare debilitating condition. In cases refractory to conservative treatment and not amenable to direct repair an augmentation becomes necessary. The preferred salvage method at our institution is augmentation with the anterior third of the gluteus maximus tendon. The aim of this study is to describe the results of 8 patients, treated for painful chronic hip abductor insufficiency with gluteus maximus muscle transfer, after a minimal follow-up of 24 months including a full clinical and MRI evaluation of the hip abductors pre- and postoperatively. METHODS: We retrospectively reviewed a consecutive series of 8 patients who were surgically managed for painful chronic hip abductor insufficiency. All patients had a Trendelenburg sign, impaired muscle strength (M ⩽ 3) as well as a complete avulsion of the hip abductors with marked fatty degeneration (⩾3). Pain levels, muscle strength, functional scores as well as a postoperative MRI was obtained after a minimal follow-up of 24 months. RESULTS: The mean age of the patients was 69 years, mean follow-up was 35 (26-54) months. Pain was significantly reduced postoperatively to VAS 2.5 from VAS 5 (p = 0.046). Trendelenburg sign remained positive in all patients and hip abductor strength did not improve significantly from 2.4 to 3.1 (p = 0.19). Complete healing of the transferred tendon was confirmed by MRI in all patients at last follow-up. CONCLUSIONS: In the setting of painful chronic hip abductor insufficiency refractory to conservative treatment with advanced muscle degeneration without the possibility of a direct reconstruction the gluteus maximus tendon transfer significantly decreased pain. The effect on hip abductor strength and patient-reported functional outcome scores is limited. Despite the modest results it remains our preferred salvage treatment option for lack of better alternatives. Larger studies are necessary to confirm these findings.

Medial Femoral Condyle Free Flap for Persistent Osseous Nonunion of the First Metatarsophalangeal Joint: A Preliminary Report of a New Surgical Indication for the Medial Femoral Condyle Free Flap.

Background: Recalcitrant or persistent nonunions of the metatarsophalangeal (MTP) joint occur following failed MTP surgery for MTP fusion, failed MTP prosthesis, for hallux rigidus or due to infection and erosion. A deficient soft tissue envelope and compromised vascular supply of tissues in this region compound further attempts to salvage the great toe and preserve function. The medial femoral condyle (MFC) free flap provides vascularized corticocancellous bone and periosteum and has been successfully used for a variety of complex hindfoot and ankle pathologies. We present an additional indication with a small cohort study demonstrating its use in persistent nonunions of the first MTP joint. Methods: A retrospective review was completed of all MFC flaps used for revision of failed first MTP joint fusion from January 2019 to November 2022. Demographic information, comorbidities, as well as clinical and radiologic follow-up was obtained from the patient charts. Results: Three patients were included with MTP nonunion and an average of 7.5 (range, 5-11) failed prior surgeries. Mean age at index surgery was 50 (range, 46-57) years. An osseous union was achieved in all patients after 82 (range, 75-88) days. Hardware removal was possible after 81 (range, 55-98) days. Mean follow-up was 17 (range, 5-31) months. We note a 100% flap success rate without returns to the operating room. The lengths of the bone flaps were 2 to 4 cm, the volumes were 8 to 12 cm3. Fixation was performed with 1 intramedullary K-wire. The recipient vessel in all patients was the dorsalis pedis artery or a tributary thereof. All arterial anastomoses were performed under the operating microscope. Conclusion: The MFC free flap is a reasonable option for salvage of complex recalcitrant or persistent nonunions of the first MTP joint. More prospective long-term studies with functional outcomes are necessary to confirm these findings. Level of Evidence: Level IV, retrospective case series.

Fasciocutaneous Free Tissue Transfer in Limb Salvage: Prior Flap as a Split-thickness Skin Graft Donor Site.

Free flap surgery for limb salvage has become the surgical standard for reconstruction of bone and soft tissue with success rates and flap survivals of 94%-95%. The soft tissue defect dictates the technique of coverage. In many cases, multiple techniques of soft tissue coverage are necessary, ranging from myocutaneous and fasciocutaneous free flaps to split-thickness skin grafts (STSGs). It has been shown that fasciocutaneous free flaps are not inferior to muscle flaps in treatment of lower leg limb salvage. Although a complete flap loss is rare, it is not uncommon to have partial flap necrosis, wound dehiscence, or secondary soft tissue defects, necessitating further minor reconstruction, which we call "touch up" skin grafts. In many of these secondary procedures, split thickness skin grafts are sufficient. We have been using the skin portion of the fasciocutaneous free flap as a donor site for harvesting STSGs for quite some time without disadvantages. We believe that minimizing additional donor site morbidity is of great importance. The free tissue transfer is insensate and readily available at the site of injury, making prepping and draping simple as well as cosmetically acceptable, as the transferred free tissue, unfortunately, is rarely a perfect fit. The associated pain, discomfort, and scar of an additional donor site can be avoided. In our case series, we did not experience any flap loss, infections, or complications. Thus, harvesting an STSG from a fasciocutaneous free flap seems to be a feasible option to be considered in limb salvage.

Extent of posterolateral tibial plateau impaction fracture correlates with anterolateral complex injury and has an impact on functional outcome after ACL reconstruction.

PURPOSE: The impact of posterolateral tibial plateau impaction fractures (TPIF) on posttraumatic knee stability in the setting of primary anterior cruciate ligament (ACL) tear is unknown. The main objective was to determine whether increased bone loss of the posterolateral tibial plateau is associated with residual rotational instability and impaired functional outcome after ACL reconstruction. METHODS: A cohort was identified in a prospective enrolled study of patients suffering acute ACL injury who underwent preoperative standard radiographic diagnostics and clinical evaluation. Patients were included when scheduled for isolated single-bundle hamstring autograft ACL reconstruction. Exclusion criteria were concurrent anterolateral complex (ALC) reconstruction (anterolateral tenodesis), previous surgery or symptoms in the affected knee, partial ACL tear, multi-ligament injury with an indication for additional surgical intervention, and extensive cartilage wear. On MRI, bony (TPIF, tibial plateau, and femoral condyle morphology) and ligament status (ALC, concomitant collateral ligament, and meniscus injuries) were assessed by a musculoskeletal radiologist. Clinical evaluation consisted of KT-1000, pivot-shift, and Lachman testing, as well as Tegner activity and IKDC scores. RESULTS: Fifty-eight patients were included with a minimum follow-up of 12 months. TPIF was identified in 85% of ACL injuries (n = 49). The ALC was found to be injured in 31 of 58 (53.4%) cases. Pearson analysis showed a positive correlation between TPIF and the degree of concomitant ALC injury (p < 0.001). Multiple regression analysis revealed an increased association of high-grade TPIF with increased lateral tibial convexity (p = 0.010). The high-grade TPIF group showed worse postoperative Tegner scores 12 months postoperatively (p = 0.035). CONCLUSION: Higher degrees of TPIFs are suggestive of a combined ACL/ALC injury. Moreover, patients with increased posterolateral tibial plateau bone loss showed lower Tegner activity scores 12 months after ACL reconstruction. LEVEL OF EVIDENCE: III.

Combining the advantages of 3-D and 2-D templating of total hip arthroplasty using a new tin-filtered ultra-low-dose CT of the hip with comparable radiation dose to conventional radiographs.

BACKGROUND: Inaccurately scaled radiographs for total hip arthroplasty (THA) templating are a source of error not recognizable to the surgeon and may lead to inaccurate reconstruction and thus revision surgery or litigation. Planning based on computed tomography (CT) scans is more accurate but associated with higher radiation exposure. The aim of this study was (1) to retrospectively assess the scaling deviation of pelvic radiographs; (2) to prospectively assess the feasibility and the radiation dose of THA templating on radiograph-like images reconstructed from a tin-filtered ultra-low-dose CT dataset. METHODS: 120 consecutive patients were retrospectively analyzed to assess the magnification error of our current THA templates. 27 consecutive patients were prospectively enrolled and a radiographic work-up in the supine position including a new tin-filtered ultra-low-dose CT scan protocol was obtained. THA was templated on both images. Radiation dose was calculated. RESULTS: Scaling deviations between preoperative radiographs and CT of ≥ 5% were seen in 25% of the 120 retrospectively analyzed patients. Between the two templates trochanter tip distance differed significantly (Δ2.4 mm, 0-7 mm, p = 0.035)), predicted femoral shaft size/cup size was the same in 45%/41%. The radiation dose of the CT (0.58 mSv, range 0.53-0.64) was remarkably low. CONCLUSION: Scaling deviations of pelvic radiographs for templating THA may lead to planning errors of ≥ 3 mm in 25% and ≥ 6 mm in 2% of the patients. 2-D templating on radiograph-like images based on tin-filtered ultra-low-dose CT eliminates this source of error without increased radiation dose. LEVEL OF EVIDENCE: Retrospective and prospective comparative study, Level III.

Accuracy of pelvic measurements on virtual radiographic projections based on computed tomography scans compared to conventional radiographs pre- and postoperatively.

BACKGROUND: The anteroposterior (ap) radiograph of the pelvis is decisive in the diagnosis of different pathologies of the hip joint. Technical advantages have reduced the radiation dose of pelvic CT to levels comparable to radiographs. The purpose of this study was to validate if standard radiographic parameters (lateral center edge angle, medial center edge angle, acetabular index, acetabular arc, extrusion index, crossover sign and posterior wall sign) can accurately be determined on radiograph-like projections reconstructed from the CT dataset pre- and postoperatively. METHODS: A consecutive series of patient with symptomatic dysplasia of the hip and a full radiologic workup (radiographs and CT scan pre- and postoperatively) who underwent periacetabular osteotomy were included. Standard radiographic parameters were compared between radiographs and radiograph-like projections by two authors pre- and postoperatively. RESULTS: A total of 16 hips (32 radiographs/32 radiograph-like projections) were included in the study. No significant difference was found between the radiographs and radiograph-like images for all parameter for both examiners. ICC between radiograph and radiograph-like projections for all investigated parameters showed good to excellent reliability (0.78-0.99) pre- and postoperatively. CONCLUSION: Radiograph-like projections show comparable results to radiographs with regard to the important investigated parameters (lateral center edge angle, medial center edge angle, acetabular index, acetabular arc, extrusion index, crossover sign and posterior wall sign). Thus, ultra-low-dose CT scans may reduce the need for conventional radiographs in pre- and postoperative analyses of 3-dimensional hip pathologies in the future, as the advantages increasingly outweigh the disadvantages.

Acetabular reconstruction with femoral head autograft in primary total hip arthroplasty through a direct anterior approach is a reliable option for patients with secondary osteoarthritis due to developmental dysplasia of the hip.

BACKGROUND: Developmental dysplasia is challenging to treat with total hip arthroplasty via the direct anterior approach (DAA). Reconstructing the former anatomy while restoring the acetabular bone stock for future revisions in this young patient collective combined with the known advantages of the DAA would be desirable. The purpose of this study was to analyze the feasibility, radiographic outcome and clinical outcome of primary uncemented total hip arthroplasty with bulk femoral head autograft for acetabular augmentation through a DAA with a minimal follow-up of 12 months. METHODS: A retrospective, consecutive series from March 2006 to March 2018 of 29 primary total hip arthroplasty with acetabular augmentation with bulk femoral head autograft through a direct anterior approach was identified. All complications, reoperations and failures were analyzed. Radiographic and clinical outcome was measured. RESULTS: 24 patients (29 hips) with a mean age of 43 (18-75) years and a mean follow-up of 35 months (12-137) were included. Surgical indication was secondary osteoarthritis for developmental dysplasia of the hip (Hartofilakidis Grade A (n = 19), B (n = 10)) in all cases. We noted no conversion of the approach, no dislocation and no acetabular loosening. The center of rotation was significantly distalized by a mean of 9 mm (0-23) and significantly medialized by a mean of 18 mm (6-29). The bone graft was fully integrated after 12 months in all cases. CONCLUSION: Acetabular reconstruction with femoral head autograft in primary THA through a direct anterior approach seems to be a reliable option for the treatment of secondary osteoarthritis in patients with DDH Hartofilakidis grade A and B. Prospective cohort studies with a large sample population and a long-term follow-up are necessary to confirm our findings.

Long-term follow-up of conservative treatment of Charcot feet.

BACKGROUND: Charcot arthropathy (CN) can ultimately lead to limb loss despite appropriate treatment. Initial conservative treatment is the accepted treatment in case of a plantigrade foot. The aim of this retrospective study was to investigate the mid- to long-term clinical course of CN initially being treated conservatively, and to identify risk factors for reactivation and contralateral development of CN as well as common complications in CN. METHODS: A total of 184 Charcot feet in 159 patients (median age 60.0 (interquartile range (IQR) 15.5) years, 49 (30.1%) women) were retrospectively analyzed by patient chart review. Rates of limb salvage, reactivation, contralateral development and common complications were recorded. Statistical analysis was performed to identify possible risk factors for limb loss, CN reactivation, contralateral CN development, and ulcer development. RESULTS: Major amputation-free survival could be achieved in 92.9% feet after a median follow-up of 5.2 (IQR 4.25, range 2.2-11.25) years. CN recurrence occurred in 13.6%. 32.1% had bilateral CN involvement. Ulcers were present in 72.3%. 88.1% patients were ambulating in orthopaedic footwear without any further aids. Presence of Diabetes mellitus was associated with reactivation of CN, major amputation and ulcer recurrence. Smoking was associated with ulcer development and necessity of amputations. CONCLUSIONS: With consistent conservative treatment of CN with orthopaedic footwear or orthoses, limb preservation can be achieved in 92.9% after a median follow-up of 5.2 years. Patients with diabetic CN are at an increased risk of developing complications and CN reactivation. To prevent ulcers and amputations, every effort should be made to make patients stop smoking. LEVEL OF EVIDENCE: III, long-term retrospective cohort study.

Lumbar spinal fusion does not increase early dislocation risk in primary total hip arthroplasty through the direct anterior approach.

INTRODUCTION: Patients with total hip arthroplasty (THA) and a concomitant lumbar spinal fusion (LSF) might have an increased incidence of revision surgery and postoperative complications such as early THA dislocation. The direct anterior approach (DAA) has gained popularity in THA due to its soft tissue-preserving nature and the relatively low dislocation risk. The purpose of the present study was to examine whether LSF patients undergoing minimally invasive THA through the DAA might have an increased risk of prosthetic-related complications compared to matched-control patients without a LSF. MATERIALS AND METHODS: Patients who underwent THA through the DAA in our institution from January 2014 to December 2018 were identified. A total of 30 primary THA also underwent LSF within 3 months from the initial operation. These patients were randomly matched (1:3) for sex, age, and body mass index with patients who underwent primary THA in our institution without a history of LSF (control group). Peri and postoperative complications, revisions, radiographic and clinical outcomes were assessed retrospectively. RESULTS: LSF patients who underwent THA through the DAA did not have an increased risk of prosthetic-related complications compared to matched-control subjects without a LSF (6.6% versus 4.4%, P < 0.05). The functional and radiological outcomes were similar between groups. CONCLUSION: LSF patients undergoing THA could benefit from the DAA similarly to patients without LSF and without increased rate of early THA dislocation. Although the complex interplay between the lumbar spine and hip in THA patients warrants further investigation, the outcomes of THA through the DAA in LSF patients appear promising. LEVEL OF EVIDENCE: Retrospective case-control study, III.

The effect of preoperative radiotherapy on surgical resectability, tumor volume and the necrosis rate of soft tissue sarcomas: A retrospective single-center analysis.

INTRODUCTION: The mainstay of soft tissue sarcoma treatment is limb preserving resection, often combined with radiotherapy, preferably preoperative radiotherapy. The goal of this study is to retrospectively assess the effect of preoperative (neoadjuvant) radiotherapy on the minimal distance to critical neurovascular structures, on tumor volume and the necrosis rate. MATERIAL AND METHODS: The data of fifty-one patients treated for a localized soft tissue sarcoma (STS) of the extremity or the trunk were retrospectively reviewed. All patients were analyzed with MR imaging before and after preoperative radiotherapy to determine the impact of radiotherapy on the precise planning and execution of the surgical excision of the tumor. The volume of the tumor as well as the distance to anatomically relevant structures were measured on MRI. Tumor type, characteristics and necrosis rate were obtained from the pathology report. RESULTS: At latest follow-up (median 51 months (range 6-113)) 32/51 (63%) patients were alive. The minimal distance between the myxoid liposarcomas (n = 12) and the vessels was significantly increased by preoperative radiotherapy from 1.09 mm [0-21.1] to 5.23 mm [0-32.70] (P = 0.045). High-grade tumors showed a significant increase in tumor volume after irradiation (p = 0.03) and a significantly greater necrosis rate than low-grade tumors (p < 0.001). CONCLUSION: Preoperative radiotherapy significantly increases the minimal distance from myxoid liposarcomas to the vessel. In the subgroup of STS that demonstratea volume reduction the distance to nerves and vessels increases, but with the low number of cases, this increase is not statistically significant. The effect of preoperative radiotherapy on the tumor volume varies greatly, whereas the subtype of myxoid liposarcoma shows a significant volume reduction in all cases.

Metatranscriptomic Analysis of Bacterial Communities on Laundered Textiles: A Pilot Case Study.

Microbially contaminated washing machines and mild laundering conditions facilitate the survival and growth of microorganisms on laundry, promoting undesired side effects such as malodor formation. Clearly, a deeper understanding of the functionality and hygienic relevance of the laundry microbiota necessitates the analysis of the microbial gene expression on textiles after washing, which-to the best of our knowledge-has not been performed before. In this pilot case study, we used single-end RNA sequencing to generate de novo transcriptomes of the bacterial communities remaining on polyester and cotton fabrics washed in a domestic washing machine in mild conditions and subsequently incubated under moist conditions for 72 h. Two common de novo transcriptome assemblers were used. The final assemblies included 22,321 Trinity isoforms and 12,600 Spades isoforms. A large part of these isoforms could be assigned to the SwissProt database, and was further categorized into "molecular function", "biological process" and "cellular component" using Gene Ontology (GO) terms. In addition, differential gene expression was used to show the difference in the pairwise comparison of the two tissue types. When comparing the assemblies generated with the two assemblers, the annotation results were relatively similar. However, there were clear differences between the de novo assemblies regarding differential gene expression.

Extra-abdominal desmoid tumor fibromatosis: a multicenter EMSOS study.

BACKGROUND: Extra-abdominal desmoid tumor fibromatosis (DTF) is a rare, locally aggressive soft tissue tumour. The best treatment modality for this patient cohort is still object of debate. QUESTIONS/PURPOSE: This paper aimed to (1) to compare the outcomes of DTF after different treatment modalities, (2) to assess prognostic factors for recurrence following surgical excision, and (3) to assess prognostic factors for progression during observation. METHODS: This was a retrospective multicenter study under the patronage of the European Musculoskeletal Oncology Society (EMSOS). All seven centres involved were tertiary referral centres for soft tissue tumours. Baseline demographic data was collected for all patients as well as data on the diagnosis, tumour characteristics, clinical features, treatment modalities and whether they had any predisposing factors for DTF. RESULTS: Three hundred eighty-eight patients (240 female, 140 male) with a mean age of 37.6 (±18.8 SD, range: 3-85) were included in the study. Two hundred fifty-seven patients (66%) underwent surgical excision of ADF, 70 patients (18%) were observed without therapy, the residual patients had different conservative treatments. There were no significant differences in terms of tumour recurrence or progression between the different treatment groups. After surgical excision, younger age, recurrent disease and larger tumour size were risk factors for recurrence, while tumours around the shoulder girdle and painful lesions were at risk of progression in the observational group. CONCLUSION: Local recurrence rate after surgery was similar to progression rates under observation. Hence, observation in DTF seems to be justified, considering surgery in case of dimensional progression in 2 consecutive controls (3 and 6 months) and in painful lesions, with particular attention to lesions around the shoulder girdle.

The quantitative influence of current treatment options on patellofemoral stability in patients with trochlear dysplasia and symptomatic patellofemoral instability - a finite element simulation.

BACKGROUND: Trochlear dysplasia is highly associated with patellofemoral instability. The goal of conservative and surgical treatment is to stabilize the patella while minimizing adverse effects. However, there is no literature investigating the quantitative influence of different treatment options on patellofemoral stability in knees with trochlear dysplasia. We created and exploited a range of finite element models to address this gap in knowledge. METHODS: MRI data of 5 knees with trochlear dysplasia and symptomatic patellofemoral instability were adapted into this previously established model. Vastus medialis obliquus strengthening as well as double-bundle medial patellofemoral ligament reconstruction and the combination of medial patellofemoral ligament reconstruction and trochleoplasty were simulated. The force necessary to dislocate the patella by 10 mm and fully dislocate the patella was calculated in different flexion angles. FINDINGS: Our model predicts a significant increase of patellofemoral stability at the investigated flexion angles (0°-45°) for a dislocation of 10 mm and a full dislocation after medial patellofemoral ligament reconstruction and the combination of medial patellofemoral ligament reconstruction and trochleoplasty compared to trochleodysplastic (P = 0.01) and healthy knees (P = 0.01-0.02). Vastus medialis obliquus strengthening has a negligible effect on patellofemoral stability. INTERPRETATIONS: This is the first objective quantitative biomechanical evidence supporting the place of medial patellofemoral ligament reconstruction and medial patellofemoral ligament reconstruction combined with trochleoplasty in patients with symptomatic patellofemoral instability and trochlear dysplasia type B. Vastus medialis obliquus strengthening has a negligible effect on patellar stability at a low total quadriceps load of 175 N.

Systematic Biomechanical Analysis of Prerequisites for Reliable Intraoperative Bonding of Polymethylmethacrylate Bone Cement in Preexisting Cement in Revision Arthroplasty.

Removal of a stable cement mantle may be invasive and time consuming and may result in unnecessary damage to bone and surrounding soft tissue. The goal of this study was to investigate the feasibility of the use of polymethylmethacrylate cement on preexisting cement as well as to explore the prerequisites for practical clinical use under standardized laboratory conditions. The strength of the cement-cement interface was evaluated with a 4-point bending to failure test, according to International Organization for Standardization 5833, as well as standardized shear strength, according to American Society for Testing and Materials D732. Various intraoperative cleaning agents were tested to remove simulated contamination with bone marrow. Contamination of the cement-cement interface with bone marrow decreases bending strength, modulus, and shear strength. Removal of the bone marrow with a degreasing agent significantly increases bending strength as well as bending modulus and can increase shear strength up to 9% compared with use of a nondegreasing agent. The cement-cement interface may reach up to 85% of bending strength, 92% of bending modulus, and comparable shear strength compared with a uniform cement block. Meticulous removal of fatty contaminant is important. Use of a degreasing agent further increases the stability of the cement-cement interface. With these precautions, it is safe to assume that the combined molecular and mechanical interlock is sufficient for most clinical applications and will not represent the weakest link in prosthetic revision. [Orthopedics. 2021;44(1):e55-e60.].

Patellofemoral instability in trochleodysplastic knee joints and the quantitative influence of simulated trochleoplasty - A finite element simulation.

BACKGROUND: Patellofemoral instability is a debilitating condition mainly affecting young patients and has been correlated with trochlear dysplasia. It can occur when the patella is insufficiently guided through its range of motion. Currently, there is no literature describing patellofemoral stability in trochleodysplastic knees and the effect of isolated trochleoplasty on patellofemoral stability. METHODS: The effect of isolated trochleoplasty in trochleodysplastic knees of patients with symptomatic patellofemoral instability was investigated using a quasi-static finite element model. MRI data of five healthy knees were segmented, meshed and a finite element analysis was performed in order to validate the model. A second validation was performed by comparing simulated patellofemoral kinematics to in-vivo values obtained from upright- weight bearing CT scans. Subsequently, five trochleodysplastic knees were modelled before and after simulated trochleoplasty. The force necessary to dislocate the patella by 10 mm and to fully dislocate the patella was calculated in various knee flexion angles between 0 and 45°. FINDINGS: The developed models successfully predicted outcome values within the range of reference values from literature. Lateral stability was significantly lower in trochleodysplastic knees compared to healthy knees. Trochleoplasty was determined to significantly increase the force necessary to dislocate the patella in trochleodysplastic knees to comparable values as in healthy knees. INTERPRETATION: This is the first study to investigate lateral patellofemoral stability in patients with symptomatic patellofemoral instability and dysplasia of the trochlear groove. We confirm that patellofemoral stability is significantly lower in trochleodysplastic knees than in healthy knees. Trochleoplasty increases patellofemoral stability to levels similar to healthy.

The influence of different patient positions on the preoperative 3D planning for surgical resection of soft tissue sarcoma in the lower limb-a cadaver pilot study.

INTRODUCTION: Complete surgical resection remains the mainstay of the treatment of soft tissue sarcomas. Intraoperative positioning of the patient is dictated by tumor location, whereas preoperative imaging is always performed in the supine position. The effect of changing the patient position on the exact location of the tumor with regard to neurovascular structures and bone is unknown. MATERIAL AND METHODS: Two fresh frozen cadavers (pelvis and legs) were thawed and warmed. Three standardized tumor models were implanted in the thigh and calf. MR/CT images of the cadavers were obtained sequentially in four different patient positions. The minimal distance of each "tumor" to neurovascular structures was measured on axial MR images and the 3D shift of the center of the tumor to the bone was measured after segmentation of the CT images. RESULTS: A significant difference of the minimal distance of the "tumor" to the femoral artery (P = 0.019/0.023) and a significantly greater number of deviations of more than 5mm/10 mm in the thigh between the supine position and the other positions compared to two supine positions (p = 0.027/0.028) were seen. The center of the "tumor" compared to the bone shifted significantly in the thigh (P < 0.001/0.002) but not the lower leg. CONCLUSION: Obtaining images in the same patient position as the planned tumor resection may become particularly relevant if computer assisted surgery, which is based on preoperative imaging, is introduced into soft tissue sarcoma surgery as the patient position significantly influences the spatial position of the tumor.

Midterm Fate of the Contralateral Foot in Charcot Arthropathy.

BACKGROUND: The contralateral foot in Charcot arthropathy or neuroarthropathy (CN) is subject to increased plantar pressure. To date, the clinical consequences of this pressure elevation are yet to be determined. The aim of this study was to evaluate ulcer and amputation rates of the contralateral foot in CN. METHODS: We abstracted the medical records of 130 consecutive subjects with unilateral CN. Rates of contralateral CN development and recurrence, contralateral ulcer development, and contralateral amputations were recorded. Statistical analysis was performed to identify possible risk factors for contralateral CN and ulcer development, and contralateral amputation. Mean follow-up was 6.2 (SD 4) years. RESULTS: After a mean of 2.5 years, 19.2% patients developed contralateral CN. Female gender was associated with contralateral CN development (odds ratio 3.13, 95% confidence interval 1.27, 7.7). Overall, 46.2% patients developed a contralateral ulcer. Among the patients who developed contralateral CN, 60% developed an ulcer. Sanders type 2 at the index foot (midfoot CN) was significantly associated with contralateral ulcer development. Ulcer-free survival (UFS) differed significantly between patients with diabetes type 1 (median UFS 5131 days) and patients with diabetes type 2 (median UFS 2158 days). A total of 25 amputations had to be performed in 22 (16.9%) patients. Three of those 22 patients (2.3%) needed major amputation. CONCLUSION: Almost 20% of patients developed contralateral CN. Nearly half of people with CN developed a contralateral foot ulceration. Patients with type 2 diabetes had significantly shorter UFS than patients with diabetes type 1. Every sixth patient needed an amputation, with the majority being minor amputations. The contralateral foot should be monitored closely and included in the treatment in patients with CN. LEVEL OF EVIDENCE: Level IV, retrospective study.