Complications of surgical management of osteopetrosis. A case report of multiple surgeries performed on one patient.

Osteopetrosis is a rare form of sclerosing bone dysplasias which in some cases requires orthopedic surgical management of its complications. It is characterized by osteosclerosis, brittle bones and obliteration of the medullary cavity. Therefore, surgery in these cases is difficult and results can be compromised by postoperative complications. We present a case of a 73-year-old patient treated at our institution in a period of 24 years. In this period, the patient had bilateral primary hip arthroplasty (THA), total knee arthroplasty, revision surgeries of both THA's and lumbar spine surgeries. The treatment of infected THA and periprosthetic fractures ended with satisfactory results but complications of the spinal surgery resulted in a poor clinical outcome.

The Impact of COVID-19 on the Orthopaedic Patient in Slovenia: Hip and Knee Replacement Surgery, 90-Day Mortality, Outpatient Visits and Waiting Times.

Introduction: The purpose of the study was to analyse the impact of the COVID-19 pandemic on the healthcare of the orthopaedic patient, i.e. numbers of hip and knee replacement surgeries, 90-day mortality, waiting times and outpatient clinic visits. Methods: The Hip (HR) and Knee Replacement (KR) records from The National Arthroplasty Registry of Slovenia in the pandemic year 2020 were compared to the year 2019. To compare reasons for revision and 90-day mortality the Chi-square test was used. The median values of the number of operations and waiting times were compared with the 95% confidence intervals. The number of outpatient clinic visits was tested with the Wilcoxon Signed Ranked test. Results: All operations fell by 19%, from 7825 to 6335. The number of Primary Total HR declined from 3530 to 2792 (21%) and the number of Primary KR from 3191 to 2423 (24%). The number of hip revisions declined by 10% and knee revisions by 25%. We did not find differences in 90-day mortality (p=0.408). Outpatient clinic visits fell from 228682 to 196582 (14%) per year. Waiting times increased by 15% for HR and by 12% for KR. Conclusion: There was an inevitable drop in the number of surgeries and outpatient clinic visits in the spring and autumn lockdown. With the reorganisation of the orthopaedic service in Slovenia, the number of KR and HR stayed at a relatively high level despite the pandemic. An epidemiological model and mechanisms for the reduction of waiting times could overcome the impact of the epidemic.

Acute Femoral Lengthening in Adults Using Step-Cut Osteotomy, Traction Table, and Proximal Femoral Locking Plate Fixation: Surgical Technique and Report of Three Cases.

Introduction: Leg-length discrepancy (LLD) can cause distinct gait and posture disorders that may lead to lifestyle-limiting disability and premature joint degeneration. The purpose of this study was to describe a novel surgical method for acute femoral lengthening in adults with symptomatic structural LLD using step-cut osteotomy, traction table, and proximal femoral locking plate fixation. Materials and methods: We retrospectively evaluated three consecutive adult patients that underwent the procedure at our institution between 2011 and 2019, describing the surgical technique and presenting a report of three cases, including complications assessment. Results: The average age was 47 years (range 38-58), average BMI was 28.1 kg/m2 (range 26.8-29.9), average ASA score was 2 (range 1-3). The mean pre-operative shortening (2 congenital, 1 posttraumatic) was 21 mm (range 20-23). The average elongation achieved was 18 mm (range 15-20). The average surgery duration was 142 min (range 120-165) and the average estimated blood loss was 558 mL (range 375-900). Symptoms were relieved after the lengthening in all three cases. We observed no complications after the mean 68 months (range 22-125) of follow-up. Conclusions: Successful correction of structural LLD is challenging, depends on patient selection, meticulous planning, surgical technique and experience. Therefore, it should be considered case-by-case. In the hands of an experienced surgeon, our method of acute femoral lengthening seems safe and suitable for carefully selected cases of structural LLD correction, where the final lengthening goal remains within the critical limits of one-stage leg lengthening and principles of traction table use.

Home-based motor imagery intervention improves functional performance following total knee arthroplasty in the short term: a randomized controlled trial.

BACKGROUND: Motor imagery (MI) is effective in improving motor performance in the healthy asymptomatic adult population. However, its possible effects among older orthopaedic patients are still poorly investigated. Therefore, this study explored whether the addition of motor imagery to routine physical therapy reduces the deterioration of quadriceps muscle strength and voluntary activation (VA) as well as other variables related to motor performance in patients after total knee arthroplasty (TKA). METHODS: Twenty-six patients scheduled for TKA were randomized to either MI practice combined with routine physical therapy group (MIp) or to a control group receiving physical therapy alone (CON). MIp consisted of maximal voluntary isometric contraction (MViC) task: 15 min/day in the hospital, then 5 times/week in their homes for 4 weeks. MViC and VA of quadriceps muscle, knee flexion and extension range of motion, pain level, along with a Timed Up-and-Go Test (TUG) and self-reported measure of physical function (assessed using the Oxford Knee Score questionnaire [OKS]) were evaluated before (PRE) and 1 month after surgery (POST). RESULTS: Significantly better rehabilitation outcomes were evident on the operated leg for the MIp group compared to CON: at POST, the MIp showed lower strength decrease (p = 0.012, η2 = 0.237) and unaltered VA, significantly greater than CON (p = 0.014, η2 = 0.227). There were no significant differences in knee flexion and extension range of motion and pain level (p > 0.05). Further, MIp patients performed better in TUG (p < 0.001, η2 = 0.471) and reported better OKS scores (p = 0.005, η2 = 0.280). The non-operated leg showed no significant differences in any outcomes at POST (all p > 0.05). In addition, multiple linear regression analysis showed that failure of voluntary activation explained 47% of the quadriceps muscle strength loss, with no significant difference in perceived level of pain. CONCLUSION: MI practice, when added to physical therapy, improves both objective and subjective measures of patients' physical function after TKA, and facilitates transfer of MI strength task on functional mobility. TRIAL REGISTRATION: Retrospectively registered on ClinicalTrials.gov NCT03684148.

Neurostructural correlates of strength decrease following total knee arthroplasty: A systematic review of the literature with meta-analysis.

Recent literature suggests that alterations in both neural and structural components of the neuromuscular system are major determinants of knee extensor muscle weakness after total knee arthroplasty (TKA). Therefore, the goal of this study was to investigate the maximal voluntary strength (MVS), voluntary muscle activation (VMA), and the cross-sectional area (CSA) of the muscle, up to 33 months after the TKA.  We searched relevant scientific databases and literature for outcomes of interest, including quadriceps MVS, VMA, and CSA. Ten studies met the inclusion criteria and involved a total of 289 patients. The quality of the studies was evaluated by Methodological Index for Non-Randomized Studies (MINORS). Results showed that quadriceps MVS markedly declines in the early postoperative period, after which it slowly and linearly recovers over time. However, the same phenomenon was not observed for VMA and CSA, which were not significantly altered after the TKA. Furthermore, a meta-regression analysis revealed that the change in VMA accounted for 39% of the relative change in quadriceps strength (R2=0.39; p=0.015) in the early postoperative period. Patients treated with TKA had considerable weakness of the quadriceps muscle, which was detectable up to 3 months after surgery. Although the change in VMA largely explains quadriceps weakness, this change and CSA differences were not significant, suggesting that other neural correlates, such as hamstrings coactivation, might alter quadriceps muscle function. Thus, more attention should be paid to address VMA failure and coactivation of antagonist muscles.  More comprehensive rehabilitation approaches may be required to target the whole neural circuit controlling the motor action.

What Factors Are Associated With Neck Fracture in One Commonly Used Bimodular THA Design? A Multicenter, Nationwide Study in Slovenia.

BACKGROUND: Femoral stems with bimodular (head-neck as well as neck-body) junctions were designed to help surgeons address patients' hip anatomy individually. However, arthroplasty registers have reported higher revision rates in stems with bimodular junctions than in stems with modularity limited to the head-neck trunnion. However, to our knowledge, no epidemiologic study has identified patient-specific risk factors for modular femoral neck fractures, and some stems using these designs still are produced and marketed. QUESTIONS/PURPOSES: The purposes of this study were (1) to establish the survival rate free from aseptic loosening of one widely used bimodular THA design; (2) to define the proportion of patients who experienced a fracture of the stem's modular femoral neck; and (3) to determine factors associated with neck fracture. METHODS: In this retrospective, nationwide, multicenter study, we reviewed 2767 bimodular Profemur® Z stems from four hospitals in Slovenia with a mean followup of 8 years (range, 3 days to 15 years). Between 2002 and 2015, the four participating hospitals performed 26,132 primary THAs; this implant was used in 2767 of them (11%). The general indications for using this implant were primary osteoarthritis (OA) in 2198 (79%) hips and other indications in 569 (21%) hips. We followed patients from the date of the index operation to the date of death, date of revision, or the end of followup on March 1, 2018. We believe that all revisions would be captured in our sample, except for patients who may have emigrated outside the country, but the proportion of people immigrating to Slovenia is higher than the proportion of those emigrating from it; however, no formal accounting for loss to followup is possible in a study of this design. There were 1438 (52%) stems implanted in female and 1329 (48%) in male patients, respectively. A titanium alloy neck was used in 2489 hips (90%) and a cobalt-chromium neck in 278 (10%) hips. The mean body mass index (BMI) at the time of operation was 29 kg/m (SD ± 5 kg/m). We used Kaplan-Meier analysis to establish survival rates, and we performed a chart review to determine the proportion of patients who experienced femoral neck fractures. A binary logistic regression model that controlled for the potential confounding variables of age, sex, BMI, time since implantation, type of bearing, diagnosis, hospital, neck length, and neck material was used to analyze neck fractures. RESULTS: There were 55 (2%) aseptic stem revisions. Survival rate free from aseptic loosening at 12 years was 97% (95% confidence interval [CI] ± 1%). Fracture of the modular neck occurred in 23 patients (0.83%) with a mean BMI of 29 kg/m (SD ± 4 kg/m.) Twenty patients with neck fractures were males and 19 of 23 fractured necks were long. Time since implantation (odds ratio [OR], 0.55; 95% CI 0.46-0.66; p < 0.001), a long neck (OR, 6.77; 95% CI, 2.1-22.2; p = 0.002), a cobalt-chromium alloy neck (OR, 5.7; 95% CI, 1.6-21.1; p = 0.008), younger age (OR, 0.91; 95% CI, 0.86-0.96; p < 0.001), and male sex (OR, 3.98; 95% CI, 1.04-14.55; p = 0.043) were factors associated with neck fracture. CONCLUSIONS: The loosening and neck fracture rates of the Profemur® Z stem were lower than in some of previously published series. However, the use of modular femoral necks in primary THA increases the risk for neck fracture, particularly in young male patients with cobalt-chromium long femoral necks. The bimodular stem we analyzed fractured unacceptably often, especially in younger male patients. For most patients, the risks of using this device outweigh the benefits, and several dozen patients had revisions and complications they would not have had if a different stem had been used. LEVEL OF EVIDENCE: Level III, therapeutic study.

Motor Imagery during Action Observation of Locomotor Tasks Improves Rehabilitation Outcome in Older Adults after Total Hip Arthroplasty.

This study aimed at determining whether the combination of action observation and motor imagery (AO + MI) of locomotor tasks could positively affect rehabilitation outcome after hip replacement surgery. Of initially 405 screened participants, 21 were randomly split into intervention group (N = 10; mean age = 64 y; AO + MI of locomotor tasks: 30 min/day in the hospital, then 3×/week in their homes for two months) and control group (N = 11, mean age = 63 y, active controls). The functional outcomes (Timed Up and Go, TUG; Four Step Square Test, FSST; and single- and dual-task gait and postural control) were measured before (PRE) and 2 months after surgery (POST). Significant interactions indicated better rehabilitation outcome for the intervention group as compared to the control group: at POST, the intervention group revealed faster TUG (p = 0.042), FSST (p = 0.004), and dual-task fast-paced gait speed (p = 0.022), reduced swing-time variability (p = 0.005), and enhanced cognitive performance during dual tasks while walking or balancing (p < 0.05). In contrast, no changes were observed for body sway parameters (p ≥ 0.229). These results demonstrate that AO + MI is efficient to improve motor-cognitive performance after hip surgery. Moreover, only parameters associated with locomotor activities improved whereas balance skills that were not part of the AO + MI intervention were not affected, demonstrating the specificity of training intervention. Overall, utilizing AO + MI during rehabilitation is advised, especially when physical practice is limited.

pH and metal concentration of synovial fluid of osteoarthritic joints and joints with metal replacements.

BACKGROUND: Due to degradation and metal dissolution during articulation of metal joint replacements the chemical periprosthetic environment may change. The aim was to establish whether metal replacements cause the local changes in pH and elevated metal concentrations. METHODS: pH was measured on samples from 167 patients: native hip and knee osteoarthritic joints, joints with hip and knee replacements revised for aseptic or septic reasons. pH of synovial fluid and periprosthetic tissue was measured perioperatively using a microelectrode and pH indicator papers for removed metal components. Metal concentrations were measured in 21 samples using inductively coupled plasma mass spectrometry. RESULTS: The mean pH value of synovial fluid at native osteoarthritic joints (n = 101) was 7.78 ± 0.38. The mean pH value of synovial fluid at revision aseptic operation (n = 58) was 7.60 ± 0.31, with statistically significant difference (p = 0.002) compared to native osteoarthritic joints. The mean pH value of synovial fluid at revision septic operation (n = 8) was 7.55 ± 0.25, with statistically significant difference (p = 0.038) compared to native osteoarthritic joints. Measurements in tissue and at stems were not reliable. In the majority of samples taken at revision increased levels of cobalt and chromium were measured. CONCLUSION: A small but statistically significant difference was observed in the pH of synovial fluid between natural joints with degenerative diseases and joints treated with metal replacements. Based on the increased metal levels we expected the value of pH to be lower, but the influence of metal ions is counteracted by the buffering capacity of human body. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2507-2515, 2017.

Comparison of ten-year survivorship of hip prostheses with use of conventional polyethylene, metal-on-metal, or ceramic-on-ceramic bearings.

BACKGROUND: To improve the long-term performance of hip prostheses, alternative bearings with metal-on-metal (MoM) and ceramic-on-ceramic (CoC) couples have been introduced. Although currently the results from the use of these bearings are in the midterm stage, there have been few comparative studies of these different bearings. METHODS: From 2000 to 2002, 487 total hip replacements were performed with use of a BICON-PLUS acetabular cup and an SL-PLUS femoral stem (Plus Orthopedics, Rotkreuz, Switzerland, now Smith & Nephew Orthopaedics). The patients were divided into three groups according to the type of bearing that was used: an MoM group (sixty-nine prostheses), a metal-on-polyethylene (MoP) group (200 prostheses), and a CoC group (218 prostheses). Patient demographic data and data with regard to revision operations were evaluated from the hospital computer database. The mean follow-up period was 8.5 years (range, 6.9 to 10.5 years). Patient activity was assessed with use of the University of California at Los Angeles activity scale. RESULTS: The mean patient age was sixty years at the time of the index arthroplasty in the MoM and CoC groups, and seventy-one years in the MoP group. Based on a scale of ten, the mean postoperative activity level was six in the CoC group, five in the MoM group, and four in the MoP group. Survival at ten years with regard to revision for any reason was 0.984, 0.956, and 0.879 for the MoP, CoC, and MoM groups, respectively. When revision for any reason was considered as the end point, survival of the MoM bearings was significantly worse than that of the MoP bearings (p = 0.005). Survival at ten years with regard to revision for aseptic loosening was 0.995, 0.990, and 0.894 for the MoP, CoC, and MoM groups, respectively. When revision for aseptic loosening was considered as the end point, survival of the MoM group was significantly worse than that of either the MoP group (p = 0.001) or the CoC group (p = 0.003). CONCLUSIONS: When comparing two groups of patients of similar mean age and mean activity level undergoing total hip arthroplasty with the use of alternative bearings, CoC bearings had better survival than did MoM bearings at the ten-year follow-up; the difference was significant when revision for aseptic loosening was defined as a failure. However, neither the CoC nor the MoM alternative bearings provided improved midterm results when compared with the results of the conventional MoP bearings. For older, less active patients, traditional metal-on-polyethylene bearings are the appropriate choice. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

The outcome of the cementless tapered SL-Plus stem: an analysis of arthroplasty register data.

PURPOSE: The aim of this study is to evaluate the outcome of the cementless SL-Plus stem in worldwide arthroplasty register datasets. METHODS: A structured analysis was conducted the registered data about the SL-Plus stem manufactured by Smith&Nephew including published data from Australia as well as previously unpublished datasets from the Registers of Lombardia, Italy and Valdoltra, Slovenia. A total of 75% of the data analysed had not been published so far. The primary outcome measure was the revision rate, calculated in revisions per 100 observed component years. We evaluated a total of 10,684 primary and 122 revision surgeries with an average follow-up period of four years. RESULTS: All datasets showed good and reproducible results for treatment with the SL-Plus stem. An average of 0.31 revisions per 100 observed component years had been reported, which is considerably below the worldwide average (1.29) found for total hip arthroplasty independent of the product. The results of a large centre did not essentially deviate from the revision rates in Lombardia, where the numbers of cases per department are relatively low on average. CONCLUSIONS: There were no indications for product defects or relevant errors in application. The SL-Plus stem can be considered a high-quality product that ensures good results also in the hands of less experienced surgeons. Data from even young registers can substantially contribute to the assessment of implants, even with the short follow-up periods. These datasets particularly allow for valid assessment of safety issues and can therefore make an essential contribution to the solution of problems of current relevance.

Survivorship and retrieval analysis of Sikomet metal-on-metal total hip replacements at a mean of seven years.

BACKGROUND: Second-generation metal-on-metal total hip replacements were introduced in the early 1990s with the aim of eliminating polyethylene wear and the resulting complications of osteolysis and aseptic loosening. The goal of the present study was to evaluate the intermediate-term results in a series of patients who were managed with one of these implants. METHODS: Between 1994 and 2002, we performed 640 total hip replacements in 591 patients with use of a Bicon-Plus cementless threaded cup with a polyethylene liner housing a metal inlay made of Sikomet low-carbon cobalt-chromium-molybdenum alloy that articulates with a Sikomet metal femoral head. Clinical and radiographic evaluation was performed retrospectively at a mean of 7.1 years postoperatively. Histologic analysis was performed on specimens retrieved from seventeen hips that were revised, and wear measurements were made for six hips that were revised. RESULTS: Thirty-four hips (thirty-four patients) were revised because of infection (six hips), aseptic loosening (twenty-three hips), pain without loosening (two hips), or other reasons (three hips). The survival rate of the prosthesis as a whole at ten years, with revision for any reason as the end point, was 0.91 (95% confidence interval, 0.88 to 0.95). The survival rate of the cup was 0.94 (95% confidence interval, 0.90 to 0.97), and that of the stem was 0.96 (95% confidence interval, 0.94 to 0.98). Linear or expansile osteolysis, or both, was observed on the radiographs of sixteen (64%) of the twenty-five hips that were revised because of aseptic loosening and/or pain. Histological analysis of pericapsular tissue was performed for seventeen of the twenty-five hips that were revised because of aseptic loosening and/or pain. Thirteen of these seventeen hips demonstrated a hypersensitivity-like reaction with aseptic inflammatory changes accompanied by moderate to extensive diffuse and perivascular infiltration of lymphocytes. In the six retrieved specimens that were subjected to wear analysis, the main wear mode was abrasive wear. The mean cumulative linear wear for the bearing was 31.3 microm, and the mean annual wear rate was 6.3 microm/yr. The mean clearance was 87.6 microm. CONCLUSIONS: After a mean duration of follow-up of seven years, aseptic loosening was the major reason for failure of Sikomet metal-on-metal prostheses. The histological findings and the prevalence of osteolysis suggest the possibility of a hypersensitivity-like immunological response to wear particles.

Poor results from the isoelastic total hip replacement: 14-17-year follow-up of 149 cementless prostheses.

BACKGROUND: To overcome the mismatch between a stiff stem and the more elastic bone, the concept of isoelasticity was introduced in the 1970s. This concept was based on the assumption that the implant and the bone should deform as one unit to avoid stress shielding. The Robert Mathys (RM) cementless total hip replacement (THR) was one of the earliest isoelastic designs. PATIENTS AND METHODS: From 1984 to 1987, we performed 149 total hip replacements in 135 patients (92 women, mean age 47 (21-72) years) using third-generation Mathys isoelastic polyacetal stem with stainless-steel heads and polyethylene cementless acetabular cups. 11 patients died before revision or before the examination for this study, and 14 were lost to follow-up. Average follow-up time for the remaining 110 patients was 15 (14-17) years. RESULTS: To date, 69 hips (64 patients) have been revised, 5 due to infection. The 10-year survival rate for any reason was 70% (66-74). In the 46 remaining patients (53 hips), the average HHS was 80 (39-100) points. 13 of these were regarded as radiographic failures, with an average HHS of 75 points. INTERPRETATION: The performance of this prosthesis was unacceptably poor. Higher debris production and poor primary fixation are believed to be the main reason for the high failure rate.

Dissociation of the metal inlay from the polyethylene liner in an uncemented threaded cup.

We describe a case of spontaneous dissociation of the metal inlay from the polyethylene cup of a sandwiched metal-on-metal total hip prosthesis manufactured from Co-28Cr-6Mo SM 21 alloy. The patient, a 51-year-old active woman, started to feel groin pain 50 months postoperatively. The pain progressed after a slight trauma and led to final revision after 66 months in situ. No signs of impingement were observed. The polyethylene cup showed an approximately 2 mm-deep groove in the superior wall, and the head was heavily worn on the lateral side. In addition to the typically observed abrasive wear patterns, several types of severe wear defects were noticed. Extensive metallosis and necrosis were observed histologically. This unusual case of substantial deformation of the head and the cup was presumed to have occurred as a result of the increased friction and consequent high wear of the metal head.

Fifty-one-year survival of a Judet polymethylmethacrylate hip prosthesis.

Revision arthroplasty of a Judet polymethylmethacrylate (PMMA) hip hemiprosthesis was performed 51 years after implantation. This makes it the first implant to have survived for longer than 50 years. No signs of aggressive osteolysis were found on histologic analysis, which confirms good tissue tolerance for PMMA. Judet's hip prosthesis did not follow the concept of low-friction arthroplasty; nevertheless, it represents an important step in the development of the hip prosthesis currently used.