Radiolucent line assessment in cemented stemmed total knee (RISK) arthroplasty: validation of a modernized classification system.

BACKGROUND: This study aims to implement and assess the inter- and intra-reliability of a modernized radiolucency assessment system; the Radiolucency In cemented Stemmed Knee (RISK) arthroplasty classification. Furthermore, we assessed the distribution of regions affected by radiolucency in patients undergoing stemmed cemented total knee arthroplasty. METHODS: Stemmed total knee arthroplasty cases over 7-year period at a single institution were retrospectively identified and reviewed. The RISK classification system identifies five zones in the femur and five zones in the tibia in both the anteroposterior (AP) and lateral planes. Post-operative and follow-up radiographs were scored for radiolucency by four blinded reviewers at two distinct time points four weeks apart. Reliability was assessed using the kappa statistic. A heat map was generated to demonstrate the reported regions of radiolucency. RESULTS: 29 cases (63 radiographs) of stemmed total knee arthroplasty were examined radiographically using the RISK classification system. Intra-reliability (0.83) and Inter-reliability (0.80) scores were both consistent with a strong level of agreement using the kappa scoring system. Radiolucency was more commonly associated with the tibial component (76.6%) compared to the femoral component (23.3%), and the tibial anterior-posterior (AP) region 1 (medial plateau) was the most affected (14.9%). CONCLUSION: The RISK classification system is a reliable assessment tool for evaluating radiolucency around stemmed total knee arthroplasty using defined zones on both AP and lateral radiographs. Zones of radiolucency identified in this study may be relevant to implant survival and corresponded well with zones of fixation, which may help inform future research.

Tibial tuberosity-trochlear groove distance: does it measure up?

Recognized anatomic variations that lead to patella instability include patella alta and trochlea dysplasia. Lateralization of the extensor mechanism relative to the trochlea is often considered to be a contributing factor; however, controversy remains as to the degree this contributes to instability and how this should be measured. As the tibial tuberosity-trochlear groove (TT-TG) is one of most common imaging measurements to assess lateralization of the extensor mechanism, it is important to understand its strengths and weaknesses. Care needs to be taken while interpreting the TT-TG value as it is affected by many factors. Medializing tibial tubercle osteotomy is sometimes used to correct the TT-TG, but may not truly address the underlying anatomical problem. This review set out to determine whether the TT-TG distance sufficiently summarizes the pathoanatomy, and if this assists with planning of surgery in patellar instability. Cite this article: Bone Jt Open 2022;3(3):268-274.

Patterns and Predictors of Outpatient Antibiotic Dispensation Following Total Hip and Knee Arthroplasty.

BACKGROUND: This study aimed to evaluate the month-to-month prevalence of antibiotic dispensation in the 12 months before and after total knee arthroplasty (TKA) and total hip arthroplasty (THA) and to identify factors associated with antibiotic dispensation in the month immediately following the surgical procedure. METHODS: In total, 4,115 THAs and TKAs performed between April 2013 and June 2019 from a state-wide arthroplasty referral center were analyzed. A cross-sectional study used data from an institutional arthroplasty registry, which was linked probabilistically to administrative dispensing data from the Australian Pharmaceutical Benefits Scheme. Multivariable logistic regression was carried out to identify patient and surgical risk factors for oral antibiotic dispensation. RESULTS: Oral antibiotics were dispensed in 18.3% of patients following primary TKA and 12.0% of patients following THA in the 30 days following discharge. During the year after discharge, 66.7% of TKA patients and 58.2% of THA patients were dispensed an antibiotic at some point. Patients with poor preoperative health status were more likely to have antibiotics dispensed in the month following THA or TKA. Older age, undergoing TKA rather than THA, obesity, inflammatory arthritis, and experiencing an in-hospital wound-related or other infectious complications were associated with increased antibiotic dispensation in the 30 days following discharge. CONCLUSION: A high rate of antibiotic dispensation in the 30 days following THA and TKA has been observed. Although resource constraints may limit routine wound review for all patients by a surgeon, a select cohort may benefit from timely specialist review postoperatively. Several risk factors identified in this study may aid in identifying appropriate candidates for such changes to follow-up care.

The influence of patellofemoral stabilisation surgery on joint congruity: an MRI surface mapping study.

BACKGROUND: In the unstable patellofemoral joint (PFJ), the patella will articulate in an abnormal manner, producing an uneven distribution of forces. It is hypothesised that incongruency of the PFJ, even without clinical instability, may lead to degenerative changes. The aim of this study was to record the change in joint contact area of the PFJ after stabilisation surgery using an established and validated MRI mapping technique. METHODS: A prospective MRI imaging study of patients with a history of PFJ instability was performed. The patellofemoral joints were imaged with the use of an MRI scan during active movement from 0° through to 40° of flexion. The congruency through measurement of the contact surface area was mapped in 5-mm intervals on axial slices. Post-stabilisation surgery contact area was compared to the pre-surgery contact area. RESULTS: In all, 26 patients were studied. The cohort included 12 male and 14 female patients with a mean age of 26 (15-43). The greatest mean differences in congruency between pre- and post-stabilised PFJs were observed at 0-10 degrees of flexion (0.54 cm2 versus 1.18 cm2, p = 0.04) and between 11° and 20° flexion (1.80 cm2 versus 3.45 cm2; p = 0.01). CONCLUSION: PFJ stabilisation procedures increase joint congruency. If a single axial series is to be obtained on MRI scan to compare the pre- and post-surgery joint congruity, the authors recommend 11° to 20° of tibiofemoral flexion as this was shown to have the greatest difference in contact surface area between pre- and post-operative congruency.

Bilateral acetabular fractures: Mechanism, fracture patterns and associated injuries.

INTRODUCTION: Acetabular fractures are uncommon and their management is often reserved for specialist pelvic and acetabular surgeons. Bilateral acetabular fractures are a particularly rare subgroup. We report the incidence, fracture pattern, mechanism of injury and outcome of patients presenting to a tertiary trauma centre with traumatic bilateral acetabular fractures. METHOD: Bilateral acetabular fractures were identified from a prospective database of acetabular fractures presenting to one institution over a six-year period. Patient notes and imaging studies were reviewed to identify demographics, mechanism of injury, Injury Severity Score, fracture pattern and management. Timing of operative management was explored. Patient outcomes were collected in the form of radiographs and Oxford Hip Scores at a minimum of one-year post injury. RESULTS: Eight patients with bilateral acetabular fracture were identified from a database which contained records of 519 patients with acetabular fractures (incidence of 1.5% amongst patients with acetabular fractures). Motor vehicle accidents were the most common mechanism. Four acetabular fracture patterns were observed within the cohort. Radiographic union occurred in all cases and Oxford Hip Scores are suggestive of moderate to well functioning hip joints. Fractures were treated as single or staged procedures. CONCLUSION: Bilateral acetabular fractures are very rare due to the unique degree and pattern of force required to fracture both acetabula. They are associated with 4 main fracture patterns and present with Injury Severity Scores that averaged 25 (severe). They are typically observed in young males with road traffic collision being the most common mechanism of injury.

Bilateral distal femoral endoprosthesis for trauma.

In this paper, we describe the outcome of bilateral distal femoral endoprosthesis for the management of acute severe trauma. We also review the literature to ascertain the published functional results of distal femoral endoprosthesis for acute trauma of native knees. In severely comminuted intra-articular fractures, such as those our patient sustained, reconstruction is not always possible, and predictable outcomes can rarely be assured with conviction. Endoprosthesis is an established treatment modality for replacement after resection in limb salvage surgery. In this regard, there is a limited but vital role that endoprosthesis can play in acute complex trauma. We demonstrate a good short-term outcome when bilateral endoprostheses are utilised for complex distal femur trauma.

Plate and screw fixation of arthroscopically assisted tibial tuberosity osteotomy: technique and results.

INTRODUCTION: We describe a fixation technique for tibial tuberosity osteotomies (TTO) utilising a plate and screw construct which adheres to established principles of bone healing. We record and discuss the complication profile and benefits of this technique. METHOD: The technique is outlined, and thirty consecutive case of TTO fixed with this combination of plate and screws were analysed during a study period from January 2018 to October 2018. All patients were followed up clinically to 3 months post-operation for the purpose of identifying early complications of surgery. Radiographic series were reviewed at 2, 6 and 12 weeks post-operation for evidence of fracture, loss of position, hardware failure and union. RESULTS: All cases went on to clinical and radiographic union by 12 weeks. We identified one case of hardware failure, one case of superficial infection and one case of stiffness requiring manipulation. CONCLUSION: We have found this technique of plate and screw construct to be effective in arthroscopically assisted TTO fixation leading to consistent union without loss of position with a low complication profile.

Survival and functional outcome of revision total knee arthroplasty with a total stabilizer knee system: minimum 5 years of follow-up.

INTRODUCTION: Revision knee arthroplasty surgery can range from patella resurfacing or polyethylene exchange, to staged revision and revision to a more constrained implant. Subsequently, the ability to elicit outcomes becomes difficult to obtain and hence information on functional outcome and survivorship for all modes of failure with a single revision system is valuable. METHODS: We retrospectively assessed 100 consecutive revision knee replacements that were converted from a primary knee replacement to a Triathlon total stabilizer (TS) knee system (Stryker Orthopaedics, Mahwah, NJ). Inclusion criteria included failure of a primary knee replacement of any cause converted to a Stryker TS knee system. Midterm outcome of at least 5 years was required. Implants survivorship, Oxford Knee Score (OKS), Forgotten Joint Score (FJS-12), Short Form (SF-) 12, reported patient satisfaction and radiographic analysis were recorded. RESULTS: The all-cause survival rate at 5 years was 89.0% [95% confidence interval (CI) 87.3 to 90.7]. The all-cause survival rate was generally static after the first 4 years. The mean OKS was 27 (SD 11.9, range 0 to 46), FJS was 32.3 (SD 30.4, range 0 to 100), SF-12 physical component summary was 40.6 (SD 17.6, range 23.9 to 67.1), and mental component summary was 48.3 (SD 15.5, range 23.9 to 69.1). Reported patient satisfaction in patients who were not re-revised was 82%. CONCLUSION: The midterm survivorship of cemented Stryker Triathlon TS knee revision for all-cause mode of failure is good to excellent; however, future follow-up is required to ensure this survivorship is observed into the long term. Despite limited functional outcome, overall patient satisfaction rates are high.

Preparing the femur before the acetabulum does not reduce total blood loss in primary total hip replacement.

INTRODUCTION: Total hip replacement is a common and effective surgical intervention for patients with debilitating joint pain but it does represent a significant surgical intervention. For such interventions, blood loss is a potential cause of morbidity and mortality. Optimisation of surgical interventions focuses on reducing such risks. The aim of this study was to determine whether the order of surgical steps, preparing the femur before or after the acetabulum, was associated with the amount of total blood loss in total hip replacement. METHODS: We performed a retrospective study of 100 patients undergoing primary total hip replacement between 2014 and 2018. This was a before and after (interrupted time series) study around the introduction of femur first preparation for total hip replacement in our unit. Fifty patients underwent a standard femoral preparation after placement of the acetabular component. The second 50 patients had the femoral canal prepared and broached prior to the acetabular component. Estimated blood volume and total blood loss associated with the perioperative period were calculated for each patient and a multiple regression analysis performed to account for other patient and surgical variables associated with perioperative blood loss. RESULTS: There was a small reduction in total blood loss for the group who underwent femoral preparation prior to acetabular preparation with a mean difference of 39 mls. This difference however was not clinically or statistically (p = 0.392) significant. Gender (p < 0.0001), Body Mass Index (BMI; p < 0.0001), preoperative haematocrit (p < 0.0001), postoperative haematocrit (p < 0.0001) and age (p = 0.004) were the only factors significantly associated with the total volume of blood loss. CONCLUSIONS: Whether the femur was prepared before or after the acetabulum did not significantly predict the total volume of blood loss for primary total hip replacement.

Open acetabular fracture: Case report and literature review.

Acetabular fractures are a rare injury, with a reported annual incidence of 3 patients per 100,000 per year. Open fractures of the acetabulum are extremely rare, with only explosive penetrating trauma (blast or gunshot injury) being previously reported. An open acetabular fracture as a result of blunt trauma is presented, in which the only indication was a wound in the buttock, in which early definitive surgical management of the injury provided a good clinical outcome.

Comparison of two extensile approaches to the knee: a cadaveric study evaluating quadriceps snip and extensile medial parapatellar approach.

PURPOSE: This study aimed to evaluate the mobility and excursion of the patella achieved by two different techniques for increasing exposure to the knee joint: the quadriceps snip and the extensile medial parapatellar approach. METHOD: Six matched intact fresh frozen cadaveric knees were used in this study. A standard medial parapatellar approach was undertaken and the patella excursion with a constant force of 5 kg was measured based on two fixed points at 0, 45 and 90 °s of knee flexion. The left knee in the matched pair was made extensile with a quadriceps snip and the right with an extensile medial parapatellar approach. The distance and change in distance as a percentage were then recorded at 0, 45 and 90 °s of knee flexion. RESULTS: Both techniques increased the mobility of the patella and its excursion. Quadriceps snip was found to give an average increase in excursion of 7 mm (12% increase in excursion), while the extensile medial parapatellar approach increased the patella distance from a fixed point by 10 mm (15% increase in excursion). Maximum displacement of the patella was consistently found to occur at 5 kg. The angle of knee flexion at which the maximum excursion was achieved was variable. CONCLUSION: The quadriceps snip and extensile medial parapatellar approach both provide increased mobility of the patella in the cadaveric knee. When exploring the options to increase exposure to the knee, the operating surgeon may wish to employ either the extensile medial parapatellar approach or the quadriceps snip. There may be clinical advantage in developing the plane between vastus medialis and rectus femoris, as opposed to cutting across the quadriceps tendon.

Disappearing hemipelvis: Low grade osteosarcoma, an unusual and poorly described variant of Paget's Sarcoma.

Paget's sarcomatous transformation is a rare and potentially fatal complication of Paget's disease. Histologically, it is typically described as a high-grade and extremely aggressive malignancy. We present an unusual radiographic series from a patient diagnosed with a low-grade Paget's osteosarcoma, a very rare and poorly described variant of the disease.