Stepwise implementation of an enhanced recovery pathway for elective total hip arthroplasty in a Swiss hospital: a cohort study.

BACKGROUND: Enhanced recovery programs after total hip arthroplasty have been shown to reduce hospital length of stay without compromising results, but yet there is a lack of data for the Swiss population. Therefore, this retrospective cohort study evaluated whether similar positive effects on clinical outcomes are present in the context of the Swiss healthcare system. METHODS: Patients who underwent elective primary total hip arthroplasty were analysed. The baseline group comprised 50 patients treated consecutively by one surgeon in 2013 according to the clinical practice guidelines. Another surgeon implemented a new standardised treatment protocol in April 2014. In January 2018, this protocol was followed by an enhanced recovery program that integrated all care providers at the hospital. The data of the baseline group (series 0) and four series of 50 patients each, two treated with the standardised treatment protocol (series 1-2) and two treated with the enhanced recovery program (series 3-4), were analysed. All patients had follow-ups at 6 weeks and 3 months after surgery. The primary outcomes were length of stay and discharge destination; the secondary outcomes were admission on the day of surgery (instead of one day prior), the use of urinary catheters, the administration of opioids, the difference between pre- and postoperative haemoglobin, blood transfusions, and adverse events within 3 months of surgery. RESULTS: The median length of stay was 10 days in the baseline group and only 5 days after the implementation of the standardised protocol and enhanced recovery program in series 4 (p <0.001). The percentage of patients discharged directly home was higher in series 4 than in the baseline group (84% vs. 66%, p = 0.085). Patients admitted to the hospital on the day of surgery increased from 2% in series 0 to 98% in series 4 (p <0.001). The use of urinary catheters was significantly higher in the baseline group (100% of patients) than in series 3 and 4 (0%) (p <0.001), and the number of patients who did not require opioids was significantly higher in series 4 than in series 0 (36% vs. 10%, p = 0.007). The median blood loss (500 ml vs. 300 ml, p <0.001), median difference in pre- and postoperative haemoglobin (29 g/dl vs. 25 g/dl, p = 0.145), and number of blood transfusions (5 vs. 2 p = 0.99) were higher in the baseline group than in series 4. The number of adverse events did not differ significantly between groups (p = 0.699). CONCLUSIONS: Almost all parameters examined in this study showed improvement, whereas the rate of adverse events was not affected and remained low. The presented data can be used as a benchmark, but details of these findings need to be confirmed in larger cohorts.

Functional assessment of total hip arthroplasty using inertial measurement units: Improvement in gait kinematics and association with patient-reported outcome measures.

Inertial measurement units (IMUs) are commonly used for gait assessment, yet their potential for quantifying improvements in gait function and patterns after total hip arthroplasty (THA) has not been fully explored. The primary aim of this study was to compare spatiotemporal parameters and sagittal plane kinematic patterns of patients with hip osteoarthritis (OA) before and after THA, and to asymptomatic controls. The secondary aim was to assess the association between dynamic hip range of motion (ROM) during walking and the Hip Osteoarthritis Outcome Scores (HOOS). Twenty-four patients with hip OA and 24 matched asymptomatic controls completed gait analyses using the RehaGait® sensor system. Patients were evaluated pre- and 1 year postoperatively, controls in a single visit. Differences in kinematic data were analyzed using statistical parametric mapping, and correlations between dynamic hip ROM and HOOS were calculated. Walking speed and stride length significantly increased (+0.08 m/s, p = 0.019; +0.06 m, p = 0.048) after THA but did not reach the level of asymptomatic controls (-0.11 m/s, p = 0.028; -0.14 m, p = 0.001). Preoperative hip and knee kinematics differed significantly from controls. After THA, they improved significantly and did not differ from controls. Dynamic hip flexion-extension ROM correlated positively with all HOOS subscores (r > 0.417; p ≤ 0.001). The change in HOOS symptoms in patients was explained by the combination of baseline HOOS symptoms and change in dynamic hip ROM (r2 = 0.748) suggesting that the additional information gained with IMU gait analysis helps to complement and objectify patient-reported outcome measures pre- and postoperatively and monitor treatment-related improvements.

Assessing Site Specificity of Osteoarthritic Gait Kinematics with Wearable Sensors and Their Association with Patient Reported Outcome Measures (PROMs): Knee versus Hip Osteoarthritis.

There is a great need for quantitative outcomes reflecting the functional status in patients with knee or hip osteoarthritis (OA) to advance the development and investigation of interventions for OA. The purpose of this study was to determine if gait kinematics specific to the disease-i.e., knee versus hip OA-can be identified using wearable sensors and statistical parametric mapping (SPM) and whether disease-related gait deviations are associated with patient reported outcome measures. 113 participants (N = 29 unilateral knee OA; N = 30 unilateral hip OA; N = 54 age-matched asymptomatic persons) completed gait analysis with wearable sensors and the Knee/Hip Osteoarthritis Outcome Score (KOOS/HOOS). Data were analyzed using SPM. Knee and hip kinematics differed between patients with knee OA and patients with hip OA (up to 14°, p < 0.001 for knee and 8°, p = 0.003 for hip kinematics), and differences from controls were more pronounced in the affected than unaffected leg of patients. The observed deviations in ankle, knee and hip kinematic trajectories from controls were associated with KOOS/HOOS in both groups. Capturing gait kinematics using wearables has a large potential for application as outcome in clinical trials and for monitoring treatment success in patients with knee or hip OA and in large cohorts representing a major advancement in research on musculoskeletal diseases.

Side to side kinematic gait differences within patients and spatiotemporal and kinematic gait differences between patients with severe knee osteoarthritis and controls measured with inertial sensors.

BACKGROUND: Kinematic changes associated with knee osteoarthritis (OA) have been traditionally measured with camera-based gait analysis. Lately, inertial sensors have become popular for gait analysis with the advantage of being less time consuming and not requiring a dedicated laboratory. RESEARCH QUESTION: Do spatiotemporal and discrete kinematic gait parameters measured with the inertial sensor system RehaGait® differ between the affected and unaffected side in patients with unilateral knee OA and between patients with severe knee OA and asymptomatic control subjects? Do these differences have a similar magnitude as those reported in the literature? METHODS: Twenty-two patients with unilateral knee OA scheduled for total knee replacement and 46 age matched control subjects were included in this study. Spatiotemporal parameters and sagittal kinematics at the hip, knee, and ankle joint were measured using the RehaGait® system while walking at a self-selected speed for a distance of 20 m and compared between groups. RESULTS: Patients with knee OA had slower walking speed, longer stride duration, shorter stride length and lower cadence (P < 0.001). Peak knee flexion during stance and swing was lower in the affected than the unaffected leg (-4.8° and -6.1°; P < 0.01). Peak knee flexion during stance and swing (-5.2° and -8.8°; P < 0.01) and knee range of motion during loading response and swing (-3.6° and -4.4°; P < 0.01) were lower than in the control group. SIGNIFICANCE: These side to side differences within patients and differences between patients with knee OA and control subjects agree with known gait alterations measured with camera-based systems. The RehaGait® inertial sensor system can detect gait alterations in patients with knee OA and is suitable for gait analysis in a clinical environment.

Kinematic changes in severe hip osteoarthritis measured at matched gait speeds.

Kinematic differences between patients with osteoarthritis (OA) and control participants have been reported to be influenced by gait speed. The purpose of this study was to experimentally detect the effect of walking speed on differences in spatiotemporal parameters and kinematic trajectories between patients with hip OA and age-matched asymptomatic participants using wearable sensors and statistical parametric mapping (SPM). Twenty-four patients with severe unilateral hip OA and 48 control participants were included in this study. Patients walked at a self-selected normal speed and control participants at self-selected normal and slow speeds. Spatiotemporal parameters and kinematic trajectories were measured with the inertial sensor system Rehagait®. Gait parameters were compared between patients with hip OA and control participants for normal and matched speed using SPM with independent sample t-tests. At self-selected normal speed, the patient group walked slower (-0.20 m/s, p < .001) and at lower cadence (-5.0 steps/minute, p < .001) as well as with smaller hip flexion (-7.4°, p < .001) and extension (-4.1°, p = .001), higher knee flexion during terminal stance (+8.0°, p < .001) and higher ankle dorsiflexion and plantarflexion (+7.1°, p < .001). While differences in spatiotemporal parameters and the ankle trajectory disappeared at matched speed, some clinically relevant and statistically significant differences in hip and knee trajectories remained. Most differences in sagittal plane gait kinematics between patients with hip OA and control participants were present for matched speed, and therefore appear to be associated with a disease rather than gait speed. Nevertheless, studies investigating hip kinematics in patients with hip OA should involve trials at matched speeds.

Measuring gait kinematics in patients with severe hip osteoarthritis using wearable sensors.

BACKGROUND: The popularity of inertial sensors in gait analysis is steadily rising. To date, an application of a wearable inertial sensor system for assessing gait in hip osteoarthritis (OA) has not been reported. RESEARCH QUESTION: Can the known kinematic differences between patients with hip OA and asymptomatic control subjects be measured using the inertial sensor system RehaGait®? METHODS: The patients group consisted of 22 patients with unilateral hip OA scheduled for total hip replacement. Forty-five age matched healthy control subjects served as control group. All subjects walked for a distance of 20 m at their self-selected speed. Spatiotemporal parameters and sagittal kinematics at the hip, knee, and ankle including range of motion (ROM) were measured using the RehaGait® system. RESULTS: Patients with hip OA walked at a slower walking speed (-0.18 m/s, P < 0.001) and with shorter stride length (-0.16 m, P < 0.001), smaller hip ROM during stance (-11.6°, P < 0.001) and swing (-11.3°, P < 0.001) and smaller knee ROM during terminal stance and swing (-9.0° and-11.5°, P < 0.001). Patients had a smaller hip ROM during stance and swing and smaller knee ROM during terminal stance and swing in the affected compared to the unaffected side (P < 0.001). SIGNIFICANCE: The differences in spatiotemporal and kinematic gait parameters between patients with hip OA and age matched control subjects assessed using the inertial sensor system agree with those documented for camera-based systems. Hence, the RehaGait® system can measure gait kinematics characteristic for hip OA, and its use in daily clinical practice is feasible.

Kinematic changes in patients with severe knee osteoarthritis are a result of reduced walking speed rather than disease severity.

BACKGROUND: Kinematic changes in patients with knee osteoarthritis (OA) have been extensively studied. Concerns have been raised whether the measured spatiotemporal and kinematic alterations are associated with disease progression or merely a result of reduced walking speed. RESEARCH QUESTION: The purpose of this study was to investigate the effect of walking speed on kinematic parameters in patients with knee OA using statistical parametric mapping (SPM). METHODS: Twenty-three patients with unilateral knee OA scheduled for a total knee replacement and 28 age matched control subjects were included in this study. Spatiotemporal parameters and sagittal plane kinematics were measured in the hip, knee, and ankle using the inertial sensors system RehaGait® while walking at a self-selected normal (patients and controls) and slow walking speed (controls) for a distance of 20 m. Gait parameters were compared between groups for self-selected walking speed and for matched walking speed using SPM with independent sample t tests. RESULTS: At self-selected walking speed, patients had significantly lower knee flexion during stance (maximum difference, -6.8°) and during swing (-11.0°), as well as higher ankle dorsiflexion during stance phase (+12.5°) and lower peak hip extension at the end of stance compared to controls (+4.2°). At matched speed, there were no significant differences in joint kinematics between groups. SIGNIFICANCE: Differences in sagittal plane gait kinematics between patients with knee OA and asymptomatic controls appear to be mainly a result of reduced walking speed. These results emphasize the importance of considering walking speed in research on gait kinematics in patients with knee OA and in clinical trials using gait parameters as outcome measures.

Accuracy of image-guided pedicle screw placement using intraoperative computed tomography-based navigation with automated referencing. Part II: thoracolumbar spine.

BACKGROUND: Image-guided spinal instrumentation may reduce complications in spinal instrumentation. OBJECTIVE: To assess accuracy, time efficiency, and staff radiation exposure during thoracolumbar screw instrumentation guided by intraoperative computed tomography (iCT)-based neuronavigation (iCT-N). METHODS: In 55 patients treated for idiopathic and degenerative deformities, 826 screws were inserted in the thoracic (T2-T12; n = 243) and lumbosacral (L1-S1; n = 545) spine, as well as ilium (n = 38) guided by iCT-N. Up to 17 segments were instrumented following a single automated registration sequence with the dynamic reference arc (DRA) uniformly attached to L5. Accuracy of iCT-N was assessed by calculating angular deviations between individual navigated tool trajectories and final implant positions. Final screw positions were also graded according to established classification systems. Clinical and radiological outcome was assessed at 12 to 14 months. RESULTS: Additional intraoperative fluoroscopy was unnecessary, eliminating staff radiation exposure. Unisegmental K-wire insertion required 4.6 ± 2.9 minutes. Of the thoracic pedicle screws 98.4% were assigned grades I to III according to the Heary classification, with 1.6% grade IV placement. In the lumbar spine, 94.4% of screws were completely contained (Gertzbein classification grade 0), 4.6% displayed minor pedicle breaches <2 mm (grade 1), and 1% of lumbar screws deviated by >2 to <4 mm (grade 2). The accuracy of iCT-N progressively deteriorates with increasing distance from the DRA, but allows safe instrumentation of up to 12 segments. CONCLUSION: iCT-N using automated referencing allows for safe, highly accurate multilevel instrumentation of the entire thoracolumbosacral spine and ilium, rendering additional intraoperative imaging dispensable. In addition, automated registration is time-efficient and significantly reduces the need for re-registration in multilevel surgery.

Accuracy of image-guided pedicle screw placement using intraoperative computed tomography-based navigation with automated referencing, part I: cervicothoracic spine.

BACKGROUND: Image-guided spinal instrumentation reduces the incidence of implant misplacement. OBJECTIVE: To assess the accuracy of intraoperative computed tomography (iCT)-based neuronavigation (iCT-N). METHODS: In 35 patients (age range, 18-87 years), a total of 248 pedicle screws were placed in the cervical (C1-C7) and upper and midthoracic (T1-T8) spine. An automated iCT registration sequence was used for multisegmental instrumentation, with the reference frame fixed to either a Mayfield head clamp and/or the most distal spinous process within the instrumentation. Pediculation was performed with navigated drill guides or Jamshidi cannulas. The angular deviation between navigated tool trajectory and final implant positions (evaluated on postinstrumentation iCT or postoperative CT scans) was calculated to assess the accuracy of iCT-N. Final screw positions were also graded according to established classification systems. Mean follow-up was 16.7 months. RESULTS: Clinically significant screw misplacement or iCT-N failure mandating conversion to conventional technique did not occur. A total of 71.4% of patients self-rated their outcome as excellent or good at 12 months; 99.3% of cervical screws were compliant with Neo classification grades 0 and 1 (grade 2, 0.7%), and neurovascular injury did not occur. In addition, 97.8% of thoracic pedicle screws were assigned grades I to III of the Heary classification, with 2.2% grade IV placement. Accuracy of iCT-N progressively deteriorated with increasing distance from the spinal reference clamp but allowed safe instrumentation of up to 10 segments. CONCLUSION: Image-guided spinal instrumentation using iCT-N with automated referencing allows safe, highly accurate multilevel instrumentation of the cervical and upper and midthoracic spine. In addition, iCT-N significantly reduces the need for reregistration in multilevel surgery.

Less invasive surgical correction of adult degenerative scoliosis. Part II: Complications and clinical outcome.

BACKGROUND: Surgical correction of adult degenerative scoliosis is a technically demanding procedure with a considerable complication rate. Extensive blood loss has been identified as a significant factor linked to unfavorable outcome. OBJECTIVE: To report on the complication profile and clinical outcomes obtained with less invasive image-guided surgical correction of degenerative (de novo) scoliosis in a high-risk population. METHODS: Thirty patients (age, 64-88 years) with progressive postural impairment, back pain, radiculopathy, and neurogenic claudication caused by degenerative scoliosis were treated by less invasive image-guided correction (3-8 segments) by multisegmental transforaminal lumbar interbody fusion and facet fusions. With a mean follow-up of 19.6 months, intraoperative blood loss, curve correction, fusion and complication rates, duration of hospitalization, incidence of hardware-related problems, and clinical outcome parameters were assessed using multivariate analysis. RESULTS: Satisfactory multiplanar correction was obtained in all patients. Mean intraoperative blood loss was 771.7±231.9 mL, time to full ambulation was 0.8±0.6 days, and length of stay was 8.2±2.9 days. After 12 months, preoperative SF12v2 physical component summary scores (20.2±2.6), visual analog scale scores (7.5±0.8), and Oswestry disability index (57.2±6.9) improved to 34.6±3.9, 2.63±0.6, and 24.8±7.1, respectively. The rate of major and minor complications was 23.4% and 59.9%, respectively. Ninety percent of patients rated treatment success as excellent, good, or fair. CONCLUSION: Less invasive image-guided correction of degenerative scoliosis in elderly patients with significant comorbidity yields a favorable complication profile. Significant improvements in spinal balance, pain, and functional scores mirrored expedited ambulation and early resumption of daily activities. Less invasive techniques appear suitable to reduce periprocedural morbidity, especially in elderly patients and individuals with significant medical risk factors.

Less invasive surgical correction of adult degenerative scoliosis, part I: technique and radiographic results.

BACKGROUND: Adult scoliosis is a condition with increasing prevalence and medical and socioeconomic importance. Surgery is fraught with a significant complication rate in an elderly multimorbid patient population. OBJECTIVE: To assess technical feasibility and radiographic results of image-guided less invasive correction of adult degenerative scoliosis. METHODS: Thirty individuals (age, 64-88 years) with progressive deformity (coronal Cobb angles > 25 degrees and < 85 degrees), intractable back pain, radiculopathy, or neurogenic claudication were treated by less invasive decompression and fusion (unilateral transforaminal interbody cage instrumentation and bilateral facet fusions) with recombinant human bone morphogenetic protein-2, spanning 3 to 8 segments (average, 6 segments), using biplanar fluoroscopy or intraoperative computed tomography (iCT)-based navigation. Accuracy of screw placement, curve correction, and fusion rate were evaluated during a mean follow-up of 19.6 months. RESULTS: With 415 screws implanted, misplacement (grade II or greater) was not observed, and no implants required revision. Spinal iCT with automated registration required 17.5 +/- 8.5 minutes (single registration for all segments); monosegmental bilateral screw insertion required 6.8 +/- 3.4 minutes. Mean sagittal (coronal) Cobb angle correction was 44.8 +/- 10.7 degrees (31.7 +/- 13.7 degrees). Mean lumbar lordosis increased from 8.8 +/- 8.9 degrees to -36 +/- 6.9 degrees, and sagittal balance was reduced from 31.6 +/- 15.2 to 8 +/- 8.4 mm. Solid fusion was confirmed in 90% of instrumented segments at 16 months. Average radiation dose to the surgeon was 0.025 mSv for single-level transforaminal lumbar interbody fusion with fluoroscopic guidance vs 0 mSv with iCT navigation. CONCLUSION: Instrumented correction of adult deformity was significantly facilitated by iCT navigation, eliminating radiation exposure to the surgeon. Intraoperative biplanar CT scout views including pelvis and shoulders allow comprehensive assessment of multiplanar deformity correction. Fusion rates obtained with less invasive access equal those of conventional open technique.

[Molecular pathways in aseptic loosening of orthopaedic endoprosthesis]. / Molekulare Signalwege der aseptischen Endoprothesenlockerung.

Operative joint replacement to treat disabling joint conditions secondary to degenerative and inflammatory arthritides has become one of the most efficacious and cost-effective procedures to relieve pain and restore joint function. However, prosthetic implants are not built to last forever and osteolysis and aseptic loosening has been associated with prosthetic arthroplasties since their introduction. The functional life of a synthetic joint is influenced by many factors including the material of the implant, operation procedures and the surgeon involved, as well as patient-related factors. Although promising developments have been achieved in this field, more than 10% of all implants still have to undergo operative revision within 15 years after the initial operation. Failure due to sepsis, fractures and dislocations has become rare; premature loosening of implants on the other hand is becoming much more important. Prosthetic loosening without concurrent infection or trauma is called aseptic loosening. It is generally accepted that small particles ("wear debris") and activated macrophages play a key role in aseptic loosening. The pathophysiology of this condition, however, is still not very well characterized. In this article, we review the molecular mechanisms and signal pathways that were unravelled as responsible factors for loosening orthopaedic implants. Finally, we discuss possible novel strategies for future therapeutic approaches.

Mechanisms of disease: Molecular insights into aseptic loosening of orthopedic implants.

Despite the success of treating rheumatic disorders with biologic therapies, joint replacement surgery still remains the final treatment option in many cases. Approximately 1.5 million joint arthroplastic operations are performed annually worldwide. Implant failure due to massive bone loss and aseptic loosening of prostheses, however, is a major complication of joint replacement, which can lead to high socioeconomic burdens both for the individual patient and for health-care systems. To date, there is no approved drug therapy to prevent or inhibit periprosthetic osteolysis, and aseptic loosening of prostheses can only be overcome by surgical revision. Research during the past decade, however, has unravelled much of the pathogenesis of aseptic prosthesis loosening and preclinical studies have identified potential targets for pharmaceutical treatments. This article highlights the importance of a cooperative interaction between rheumatologists and orthopedic surgeons, and presents novel insights into the molecular mechanisms behind aseptic loosening of prostheses. In addition, we outline potential perspectives for the development of future therapeutic strategies for this devastating complication.

Increased polyethylene wear after cementless ABG I total hip arthroplasty.

INTRODUCTION: The cementless, hydroxyapatite-coated Anatomique Benoist Giraud-I (ABG-I) hip endoprosthesis represented a modern implant in the 1990s. The aim of the current retrospective study was to evaluate the clinical and radiological results of this prosthesis. In addition, an analysis of the complications and retrieved implants was conducted. MATERIALS/METHODS: The medium-term results (follow-up 5.23 years) of 193 hip joints are presented. Of 158 total cohorts, 81.9% was able to undergo follow-up performed with standardized clinical and radiological investigations. Physical characteristics of the patients and the underlying disease prompting the need for total hip arthroplasty, as well as a clinical score (Merle d'Aubigné) were recorded. At the time of follow-up, a radiologic examination of all patients with a standardized evaluation was performed. In addition, the migration of the acetabular cup and femoral head as well as polyethylene wear could be determined digitally in 118 cases (61.1%) using one-picture Roentgen analysis. RESULTS: Clinical results, as measured with a Merle d'Aubigné Score increase from 8.4 to 16.2, were very good. Radiographs demonstrated successful osseous integration of the anatomically molded shaft. Within the period of the investigation, no revision procedures of the femoral shaft were necessary. However, the rate of polyethylene abrasion of 0.23 mm/year was markedly high. 13.9% of hips (n = 27) required acetabular cup revision due to wear. This calculates to a prosthesis 7-year survival probability of 63%. Intraoperative findings during the revision cases showed extensive periacetabular osteolysis with foreign body granulation tissue. Analysis of data from the total patient cohort versus data from cases requiring revision showed a significantly increased frequency of high polyethylene wear in young active patients as well as in cases where an unfavorable acetabular cup to femoral head relation existed in correspondence with polyethylene thickness. There is evidence, however, that suggests that multifactorial causes for the increased wear are significant in regards to the principal material and technical features of the prosthesis. CONCLUSION: On the basis of these results, it is strongly recommended that all patients treated with an ABG-I hip endoprosthesis should receive close clinical and most importantly close radiologic follow-up.

Robotic total knee arthroplasty: the accuracy of CT-based component placement.

BACKGROUND: Accurate alignment of the components in total knee arthroplasty is important. By use of postoperative CT controls, we studied the ability of a robotic effector to accurately place and align total knee arthroplasty (TKA) components according to a purely CT-based preoperative plan. PATIENTS AND METHODS: Robotic TKA was performed in 13 patients (6 men) with primary gonarthrosis. Locator screws were placed into femur and tibia under spinal anesthesia. A CT-scan including the femoral head, knee and ankle was performed. In the preoperative planning software, virtual components were positioned into the CT volume. In a second operation, the robot milled femur and tibia with a high-speed milling tool according to the preoperative plan. On the 10th day, CT controls were performed following the same protocol as preoperatively. RESULTS: The mean deviation of the postoperative from the preoperatively planned mechanical axis was 0.2 degrees (95% CI: -0.1 degrees to 0.5 degrees ). The accuracy of angular component placement in frontal, sagittal and transverse planes was within +/-1.2 degrees , and the accuracy of linear component placement in mediolateral, dorsoventral and caudocranial directions was within +/-1.1 mm. INTERPRETATION: Robotic TKA allows placement of components with unparalleled accuracy, but further development is mandatory to integrate soft-tissue balancing into the procedure and make it faster, easier and cheaper.

Complications after total knee arthroplasty: a comprehensive report.

In most reports of complications following TKA, the method of assessment and report of complications is not defined specifically. It is thus unclear whether certain complications did not occur or were simply not assessed at all. A detailed list of possible complications following TKA was developed, and the occurence of complications in 567 primary TKAs was followed up meticulously according to this list for one year postoperatively. The proportion of knees with complications was 23.6%. A revision operation was performed in 5.6%. The most frequent complication was delayed wound healing. Only a worldwide accepted standard list of well-defined complications will allow comparison of future studies on complications in TKA. For purposes of quality control, the amount of detail recorded must be weighed carefully against its practical value.

The internal calcar septum and its contact with the virtual stem in THR: a computer tomographic evaluation.

The internal calcar septum is a ridge of cortical bone protruding from the inner cortical wall of the proximal femur into the medullary canal. It extends from the lesser trochanter into the femoral neck and narrows the femoral cavity in its dorsal third. This region is essential for THR stability, but the degree of contact between the septum and standard THR implants has never been studied. We obtained CT scans of 50 arthrotic hip joints from patients requiring THR. Virtual stems (50 straight/wedge-shaped and 50 anatomic stems) were placed in CT images of the femora using a PC-based preoperative planning unit. The dimensions of the septum, degree and location of contact between the septum and implants were recorded. A septum of cortical density was seen in 49/50 CT scans. It was 11 (2.9) mm long (medial-lateral), 3.5 (0.7) mm wide and 32 (10) mm high (caudal-cranial, mean (SD)). 94/100 implanted virtual stems showed direct contact with the septum. 31 straight stems and 5 anatomical stems were supported by the septum along their dorsal side. The internal calcar septum can be consistently seen on CT scans of patients needing THR and it probably contributes to THR stability.

Cementless total hip replacement with subtrochanteric femoral shortening for severe developmental dysplasia of the hip.

INTRODUCTION: Total joint replacement in patients suffering from developmental dysplasia of the hip poses specific technical difficulties due to insufficient bone stock at the site of the original and secondary acetabulum and a narrow, cranially displaced proximal femur. MATERIALS AND METHODS: Twelve hips with severe congenital dislocation (4 Crowe type II, 5 type III, 3 type IV) were treated with cementless, porous structured total hip replacement. The cup was implanted at the anatomic height, a femoral segment was resected below the minor trochanter to reduce the femoral component in all cases. RESULTS: One femoral component was exchanged for a longer stem after 2 months due to insufficient fit and fill. After a mean follow-up of 5.1 years, there were no further revisions or radiographic signs of loosening. No cup was revised or loose radiographically. Harris hip score (mean) improved from 36 to 82 points, mean leg length discrepancy was reduced from 5.4 to 1.3 cm. CONCLUSION: The cementless technique described is useful in cases of severe congenital dislocation of the hip when the cup is implanted at the anatomic level, and implant reduction is not possible despite thorough soft-tissue release or not advisable because of excessive limb lengthening. A reconstruction of the original joint center and good mid-term results are demonstrated.

Biological fixation of hydroxyapatite-coated versus grit-blasted titanium hip stems: a canine study.

BACKGROUND: The purpose of the study was to evaluate the influence of a proximal hydroxyapatite (HA) coating in comparison with a grit-blasted titanium surface of an anatomic hip stem in an animal model over a maximum duration of 2 years. METHODS: Thirty adult dogs underwent implantation of either a proximally HA-coated or a grit-blasted anatomic titanium stem. The animals were clinically evaluated for their walking ability, and serial radiographs were taken. The femora were assessed histomorphologically at set time points from 6 weeks to 2 years postoperatively. Undecalcified thin section specimens through the proximal and distal portion of the coating or grit blasting were prepared. The percentage of implant surface with direct bone contact without connective tissue involvement was determined. RESULTS: Radiographically, animals with uncoated prostheses showed characteristic signs of loosening more frequently. Histomorphometrically, an average of 65% of the surface of HA-coated implants had bone contact, but only 14.7% of the surface of grit-blasted prostheses ( p=0.0001). There was no relationship between bone contact and the duration of implantation of the prosthesis, either for the coated or for the uncoated prostheses. HA coating enhances osseointegration of an anatomic hip stem. CONCLUSION: Anatomic stems with rounded design require a surface coating or surface structure, since the mere grit-blasting of the titanium surface does not ensure osseointegration in this animal model.

New aspects in the histological examination of polyethylene wear particles in failed total joint replacements.

The most important long-term complication in total joint replacements is aseptic osteolysis. Wear particles such as polyethylene (PE) debris are considered to be one of the causes that play a central role. Several studies indicated that PE can be visualised in paraffin-embedded tissue sections not only by polarised light, but also after oil red staining. To determine whether oil red staining enables sensitive detection of PE, we examined staining of mechanically-produced PE particles by oil red. Furthermore, we studied oil red staining of paraffin-embedded tissue specimens of patients with failed uncemented and cemented total knee and hip prostheses. We applied double labelling of sections by immunohistochemistry using the macrophage marker anti-CD68 and oil red staining. We found that oil red stains both isolated PE particles and PE particles in paraffin-embedded tissue sections. Polymethylmethacrylate particles in failed cemented arthroplasties did not stain in paraffin sections. Double labelling showed strong colocalisation of CD68 and PE. We suggest that oil red staining is a sensitive method to detect PE particles. Oil red staining is particularly helpful in these cases which show a characteristic histological feature of aseptic prosthesis loosening without particles being detectable with routine microscopy and polarised light. We also established that immunohistochemical methods can be applied together with the oil red staining method.