Comparison of the Manchester-Oxford Foot Questionnaire (MOXFQ) and the Self-Reported Foot and Ankle Outcome Score (SEFAS) in patients with foot or ankle surgery.

BACKGROUND: Patient-reported outcome measures are a critical tool in evaluating the efficacy of orthopedic procedures. The intention of this study was to compare the psychometric properties of the Manchester-Oxford Foot Questionnaire (MOXFQ) and the Self-Reported Foot and Ankle Outcome Score (SEFAS) in patients with foot or ankle surgery. METHODS: 177 patients completed both scores and FAOS, Foot and Ankle Outcome Score (FAOS), Short Form 36 (SF-36) and numeric scales for pain and disability (NRS) before and after surgery. Test-Retest reliability, internal consistency, floor and ceiling effects, construct validity, responsiveness and minimal important change were analyzed. RESULTS: The MOXFQ and SEFAS demonstrated excellent test-retest reliability with interclass correlation coefficient values >0.9 Cronbach's alpha (α) values demonstrated strong internal consistency. No floor or ceiling effects were observed for both questionnaires. As hypothesized MOXFQ subscales correlated strongly with corresponding SEFAS, FAOS and SF-36 domains. MOXFQ subscales showed excellent responsiveness between preoperative assessment and postoperative follow-up, whereas SEFAS demonstrated moderate responsiveness. CONCLUSIONS: The MOXFQ and SEFAS demonstrated good psychometric properties and proofed to be valid and reliable instruments for use in foot and ankle patients. MOXFQ showed better outcomes in responsiveness.

Long - term survivorship and clinical results of the navigated withdrawn ASR ™.

INTRODUCTION: Primary goals of the study were to present the mid - to long - term survivorship and clinical, radiological and metal serological results of the first stem - navigated ASR™ resurfacing at our clinic. Secondary goals were to determine the influence of stem - navigation on the outcome and risk factors for revision in our cohort. METHODS: From Mai 2006 to Mai 2009 46 ASR™ resurfacing hip systems have been implanted in 43 patients with a median age of 55 years. At final follow - up (33 patients with a mean follow -up of 89,6 months) guidelines were followed and HHS and HOOS were completed. Inclination, NSA and SSA were measured on radiographs and signs of loosening were graded. Risk factors for revision were compared in the non - revision and revision group. RESULTS: Mean cumulative survival of the prosthesis after 99,9 Months was 81,8%. At final follow - up 8 revisions were performed. Median HHS was 97, HOOS was 87,2. Four prostheses showed signs of loosening and nine heterotopic ossifications. All shaft components, except one, were placed in minimal valgus position to avoid risk for fracture. Age and diameter of the femoral component were significantly different between the non - revision and revision group. DISCUSSION: Survivorship is comparable to numbers found in other studies. Patients with complete final follow - up in general had good objective and subjective scores and few signs of loosening in the radiological follow - up. Navigation might have a positive effect on reduction of risk for fracture. Age and diameter of the femoral component seem to influence the outcome.

Reliability, validity and responsiveness of the German Manchester-Oxford Foot Questionnaire (MOXFQ) in patients with foot or ankle surgery.

BACKGROUND: Patient-reported outcome measures are a critical tool in evaluating the efficacy of orthopaedic procedures. The intention of this study was to develop and culturally adapt a German version of the Manchester-Oxford Foot Questionnaire (MOXFQ) and to evaluate reliability, validity and responsiveness. METHODS: According to guidelines forward and backward translation has been performed. The German MOXFQ was investigated in 177 consecutive patients before and 6 months after foot or ankle surgery. All patients completed MOXFQ, Foot and Ankle Outcome Score (FAOS), Short form 36 and numeric scales for pain and disability (NRS). Test-Retest reliability, internal consistency, floor and ceiling effects, construct validity and minimal important change were analyzed. RESULTS: The German MOXFQ demonstrated excellent test-retest reliability with ICC values >0.9 Cronbach's alpha (α) values demonstrated strong internal consistency. No floor or ceiling effects were observed. As hypothesized MOXFQ subscales correlated strongly with corresponding FAOS and SF-36 domains. All subscales showed excellent (ES/SRM >0.8) responsiveness between preoperative assessment and postoperative follow-up. CONCLUSIONS: The German version of the MOXFQ demonstrated good psychometric properties. It proofed to be a valid and reliable instrument for use in foot and ankle patients.

First application of segmental trabecular metal cones in a custom-made revision tumor prosthesis of the knee: A technical note.

BACKGROUND: Tumor prostheses are established as a standard procedure in tumors of the lower extremities. Septic and aseptic loosening remains the main reason for the failure of tumor prostheses. Due to bone defects, the possibilities of anchoring revision prostheses are limited. Trabecular metal cones are established in prosthetic revision surgery. However, the use of segmental trabecular metal cones in a custom-made tumor revision prosthesis has not yet been described. OBJECTIVE: A 58-year-old patient, who initially received a resection of the distal femur and reconstruction with a tumor prosthesis due to chondrosarcoma, attended our clinic. Because of aseptic loosening of this tumor prosthesis, revision surgery was indicated. METHODS: On account of huge bone defects, a reconstruction using a modular standard prosthesis was not possible. In order to prevent further resection of the bone and not replace the total femur, a custom-made revision tumor prosthesis was implanted. RESULTS: After preoperative planning and explantation of the loosened prosthesis, a partially cemented custom-made revision tumor prosthesis was successfully implanted using a Revitan® Curved revision stem with a custom-made Revitan® -Taperadapter and a custom-made segmental trabecular metal cone connected to a custom-made titanium segmental distal femur and a Zimmer® NexGen® RH Knee Tibia with a straight stem (Zimmer, Inc., USA). CONCLUSIONS: The application of segmental trabecular metal in a custom-made revision tumor prosthesis offers a new option to the previously existing treatment strategies.

[Treatment of Hallux Valgus: Current Diagnostic Testing and Surgical Treatment Performed by German Foot and Ankle Surgeons]. / Aktuelle diagnostische und therapeutische Vorgehensweise bei Hallux-valgus-Deformität ­ Ergebnisse einer bundesweiten Umfrage und Vergleich mit der internationalen Literatur.

BACKGROUND: Hallux valgus is one of the most prevalent foot deformities, and surgical treatment of Hallux valgus is one of the most common procedures in foot and ankle surgery. Diagnostic and treatment standards show large variation despite medical guidelines and national foot and ankle societies. The aim of this nationwide survey is a description of the current status of diagnostics and therapy of Hallux valgus in Germany. MATERIAL AND METHODS: A nationwide online questionnaire survey was sent to two German foot and ankle societies. The participants were asked to answer a questionnaire of 53 questions with four subgroups (general, diagnostics, operation, preoperative management). Surgical treatment for three clinical cases demonstrating a mild, moderate and severe Hallux valgus deformity was inquired. RESULTS: 427 foot and ankle surgeons answered the questionnaire. 388 participants were certified foot and ankle surgeons from one or both foot and ankle societies. Medical history (78%), preoperative radiographs (100%) and preoperative radiographic management (78%) are of high or very high importance for surgical decision pathway. Outcome scores are used by less than 20% regularly. Open surgery is still the gold standard, whereas minimally invasive surgery is performed by only 7%. CONCLUSION: Our survey showed that diagnostic standards are met regularly. There is a wide variation in the type of procedures used to treat Hallux valgus deformity. TMT I arthrodesis is preferred in severe Hallux valgus, but also used to treat moderate and mild deformities. Minimally invasive surgery is still used by a minority of surgeons. It remains to be seen, to what extent minimally invasive surgery will be performed in the future.

Reliability, validity and responsiveness of the German self-reported foot and ankle score (SEFAS) in patients with foot or ankle surgery.

BACKGROUND: Patient-reported outcome measures are a critical tool in evaluating the efficacy of orthopedic procedures and are increasingly used in clinical trials to assess outcomes of health care. The intention of this study was to develop and culturally adapt a German version of the Self-reported Foot and Ankle Score (SEFAS) and to evaluate reliability, validity and responsiveness. METHODS: According to Cross Cultural Adaptation of Self-Reported Measure guidelines forward and backward translation has been performed. The German SEFAS was investigated in 177 consecutive patients. 177 Patients completed the German SEFAS, Foot and Ankle Outcome Score (FAOS), Short-Form 36 and numeric scales for pain and disability (NRS) before and 118 patients 6 months after foot or ankle surgery. Test-Retest reliability, internal consistency, floor and ceiling effects, construct validity and minimal important change were analyzed. RESULTS: The German SEFAS demonstrated excellent test-retest reliability with ICC values of 0.97. Cronbach's alpha (α) value of 0.89 demonstrated strong internal consistency. No floor or ceiling effects were observed for the German version of the SEFAS. As hypothesized SEFAS correlated strongly with FAOS and SF-36 domains. It showed moderate (ES/SRM > 0.5) responsiveness between preoperative assessment and postoperative follow-up. CONCLUSION: The German version of the SEFAS demonstrated good psychometric properties. It proofed to be a valid and reliable instrument for use in foot and ankle patients. TRIAL REGISTRATION: DRKS00007585.

Assessment of reliability, validity, responsiveness and minimally important change of the German Hip dysfunction and osteoarthritis outcome score (HOOS) in patients with osteoarthritis of the hip.

Patient-reported outcome measures are a critical tool in evaluating the efficacy of orthopedic procedures. The intention of this study was to evaluate reliability, validity, responsiveness and minimally important change of the German version of the Hip dysfunction and osteoarthritis outcome score (HOOS). The German HOOS was investigated in 251 consecutive patients before and 6 months after total hip arthroplasty. All patients completed HOOS, Oxford-Hip Score, Short-Form (SF-36) and numeric scales for pain and disability. Test-retest reliability, internal consistency, floor and ceiling effects, construct validity and minimal important change were analyzed. The German HOOS demonstrated excellent test-retest reliability with intraclass correlation coefficient values > 0.7. Cronbach´s alpha values demonstrated strong internal consistency. As hypothesized, HOOS subscales strongly correlated with corresponding OHS and SF-36 domains. All subscales showed excellent (effect size/standardized response means > 0.8) responsiveness between preoperative assessment and postoperative follow-up. The HOOS and all subdomains showed higher changes than the minimal detectable change which indicates true changes. The German version of the HOOS demonstrated good psychometric properties. It proved to be valid, reliable and responsive to the changes instrument for use in patients with hip osteoarthritis undergoing total hip replacement.

Atraumatic Femoral Head Necrosis in Adults.

BACKGROUND: Atraumatic necrosis of the femoral head is a common cause of hip arthrosis in middle age. In Germany, it affects 5000-7000 patients per year, corresponding to an incidence of 0.01%. Though rarer than primary hip arthrosis, it is still of major clinical and socio-economic significance. Patients with this problem should be diagnosed early and given stage-appropriate treatment. METHODS: This review is based on pertinent publications that were retrieved by a selective search in the PubMed, Embase, Medline, and Cochrane Library databases using the terms "osteonecrosis," "femoral head necrosis," "diagnosis," "classification," "conservative treatment," "surgical treatment," "joint preservation," "osteotomy," and "arthroplasty," as well as a recent guideline on atraumatic necrosis of the femoral head in adults. RESULTS: The etiology and pathogenesis of atraumatic femoral head necrosis in adults are not yet fully clear. The main risk factor is prolonged corticosteroid treatment. Nonspecific complaints and an initially normal plain x-ray of the hip can delay the diagnosis. The diagnosis is established by plain x-ray, computerized tomography, magnetic resonance tomography, and scintigraphy. Conservative treatment alone is not considered adequate. The range of surgical treatments includes joint-preserving and (for more severe necrosis) joint-resecting methods. CONCLUSION: Atraumatic femoral head necrosis in adults is a disease that progresses in stages; depending on its stage, it can either be cured or lead to hip arthrosis. A full cure is possible only in early stages. Current research focuses on the effect of new drugs on the intermediateand long-term outcome.

Lower Back Pain with Sciatic Disorder Following L5 Dermatome Caused by Herpes Zoster Infection.

We report the case of a 62-year-old patient with lower back pain radiating into the right leg accompanied by numbness. The pain had an acute onset and was resistant to conservative pain treatment. A magnetic resonance imaging (MRI) scan of the lumbar spine showed no degenerative discovertebral lesions, but a swelling of the nerve root supplying the affected dermatome. For pain treatment the patient received lumbar epidural infiltrations. During this treatment the patient suddenly developed a skin rash with grouped vesicular blisters on an erythematous ground. After the diagnosis of a lumbar herpes zoster and an acyclovir treatment, the patient could be discharged in an ameliorated condition. This case demonstrates the importance to consider rare causes of lumbosciatic pain and disorders and to acknowledge unspecific changes in a MRI scan.

Zonal T2* and T1Gd assessment of knee joint cartilage in various histological grades of cartilage degeneration: an observational in vitro study.

OBJECTIVES: Accurate assessment of cartilage status is increasingly becoming important to clinicians for offering joint preservation surgeries versus joint replacements. The goal of this study was to evaluate the validity of three-dimensional (3D), gradient-echo (GRE)-based T2* and T1Gd mapping for the assessment of various histological severities of degeneration in knee joint cartilage with potential implications for clinical management. METHODS: MRI and histological assessment were conducted in 36 ex vivo lateral femoral condyle specimens. The MRI protocol included a 3D GRE multiecho data image combination sequence in order to assess the T2* decay, a 3D double-echo steady-state sequence for assessment of cartilage morphology, and a dual flip angle 3D GRE sequence with volumetric interpolated breathhold examination for the T1Gd assessment. The histological sample analysis was performed according to the Mankin system. The data were then analysed statistically and correlated. RESULTS: We observed a significant decrease in the T2* and T1Gd values with increasing grades of cartilage degeneration (p<0.001) and a moderate correlation between T2* (r=0.514)/T1Gd (r=0.556) and the histological grading of cartilage degeneration (p<0.001). In addition, we noted a zonal variation in the T2* and T1Gd values reflecting characteristic zonal differences in the biochemical composition of hyaline cartilage. CONCLUSIONS: This study outlines the potential of GRE-based T2* and T1Gd mapping to identify various grades of cartilage damage. Early changes in specific zones may assist clinicians in identifying methods of early intervention involving the targeted joint preservation approach versus moving forward with unicompartmental, bicompartmental or tricompartmental joint replacement procedures. TRIAL REGISTRATION NUMBER: DRKS00000729.

Pre-operative arthritis severity as a predictor for total knee arthroplasty patients' satisfaction.

PURPOSE: Studies have shown that up to 25% of TKA patients are dissatisfied with the implanted knee, even if registry data shows ten-year revision rates below 5%. It has been the question of our study, if it would be possible to identify those patients at risk for dissatisfaction pre-operatively. METHODS: The data of 1,121 consecutive TKA patients with a follow-up between one and six years have been analysed retrospectively. Demographic, radiologic and perioperative variables have been recorded and all patients were asked by questionnaire for satisfaction with the implanted knee. Logistic regression models have been used to identify significant risk factors. RESULTS: The data of 996 patients (89%) were complete, 849 (85.2%) reported satisfaction and 147 (14.8%) dissatisfaction. Patients' satisfaction was independent of the time after operation (p = 0.285). The only factor which influenced patients' satisfaction was the osteoarthritic severity. In comparison to severe arthritis Kellgren Lawrence IV°, the risk for dissatisfaction was 2.556-fold elevated for arthritis grade III° (p < 0.001) and 2.956-fold higher for grade II° (p = 0.001). CONCLUSIONS: Patients suffering from mild or moderate osteoarthritis are at risk for dissatisfaction after TKA. The TKA indication in those patients should therefore be critically proven. Furthermore, to adjust patients' expectations, the elevated dissatisfaction risk in case of mild or moderate osteoarthritis should be included into patients' pre-operative information.

Validity of gradient-echo three-dimensional delayed gadolinium-enhanced magnetic resonance imaging of hip joint cartilage: a histologically controlled study.

OBJECTIVE: To validate gradient-echo three-dimensional (3D) delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) by means of histological analyses in the assessment of hip joint cartilage. MATERIALS AND METHODS: Twenty-one femoral head specimens collected from 21 patients (7 males, 14 females, mean age: 60.9 ± 9.6 years; range: 37.6-77.3 years), who underwent total hip replacement for symptomatic hip joint osteoarthritis, underwent MRI and histological assessment. A region of 2 cm(2) at the weight-bearing area was marked with four pins to enable multi-planar MRI reformatting to be matched with histological sections. MRI was performed at 3T with a 3D double-echo steady-state (DESS) sequence for morphological cartilage assessment and 3D Volumetric Interpolated Breathhold Examination (VIBE) for T1(Gd) mapping. Histological sections were evaluated according to the Mankin score system. Total Mankin score, grade of toluidine staining (sensitive for glycosaminoglycan content) and a modified Mankin score classification system with four sub-groups of cartilage damage were correlated with MRI data. RESULTS: Spearman's rho correlation analyses revealed a statistically significant correlation between T1(Gd) mapping and histological analyses in all categories including total Mankin score (r=-0.658, p-value ≤ 0.001), toluidine staining (r=-0.802, p-value<0.001) and modified Mankin score (r=-0.716, p-value<0.001). The correlation between morphological MRI and histological cartilage assessment was statistically significant but inferior to the biochemical cartilage MRI (r-values ranging from -0.411 to 0.525, p-values<0.001). CONCLUSIONS: Gradient-echo dGEMRIC is reliable while offering the unique features of high image resolution and 3D biochemically sensitive MRI for the assessment of early cartilage degeneration.

Influence of computer navigation on TKA revision rates.

PURPOSE: We performed this study to determine whether the use of imageless navigation reduces revision rates after total knee arthroplasty (TKA). METHODS: Data of 1,121 consecutive primary TKA with a follow-up of one to six years were retrospectively analysed. Following the conversion of the standard technique from conventional to navigated procedures, these data included the last 342 conventional and first 779 navigated procedures performed in our clinic. Demographic and perioperative covariates were recorded. All patients were asked by post to report instances of revisions. RESULTS: Data of 1,054 patients (94 %) were complete. Mean follow-up was 3.9 years for conventional and 2.4 years for navigated operations. Cumulative revision rate averaged 4.7 % for conventional and 2.3 % for navigated procedures. Cox's proportional hazard model was used to assess the effect of covariates on survival, resulting in significantly lower revision rates for older patients (p < 0.001) and for the navigated technique (p = 0.012). The reduced revision rate for navigated operations was mainly caused by a significantly reduced rate of aseptic implant loosening (1.9 % vs. 0.1 %, p = 0.024). CONCLUSIONS: Our study showed lower revision rates when computer navigation was used. However, due to the retrospective uncontrolled design, further prospective trials will be necessary to further evaluate this effect.

Is the effect of a posterior cruciate ligament resection in total knee arthroplasty predictable?

PURPOSE: It is broadly supposed that in total knee arthroplasty, the flexion/extension gap ratio is increased after resection of the posterior cruciate ligament (PCL). However, studies are rare and results are inconsistent. Therefore, this study was conducted to determine whether PCL release regularly increases the flexion gap. METHODS: Data from 50 consecutive posterior stabilised knee prostheses were analysed retrospectively. Using imageless computer navigation, the joint-gap width was measured over the entire range of motion before and after PCL release. RESULTS: PCL release had no effect on the extension gap, but it increased the flexion gap significantly. An increase of >3 mm occurred in 36% of patients and of >5 mm in 12%. No clinically relevant effect (<2 mm) was found in 44% of patients. CONCLUSION: PCL release increased the flexion/extension gap ratio on average, but the individual effect could not be predicted. Therefore, we recommend PCL release before the femoral resections are performed, as this step mainly determines the ratio between extension and flexion gap.

Displays mounted on cutting blocks reduce the learning curve in navigated total knee arthroplasty.

The use of computer navigation in total knee arthroplasty (TKA) improves the implant alignment but increases the operation time. Studies have shown that the operation time is further prolonged due to the surgeon's learning curve, and longer operation times have been associated with higher morbidity risks. It has been our hypothesis that an improvement in the human-machine interface might reduce the time required during the learning curve. Accordingly, we asked whether the use of navigation devices with a display fixed on the surgical instruments would reduce the operation time in navigated TKAs performed by navigation beginners. Thirty medical students were randomized and used two navigation devices in rotation: these were the Kolibri® device with an external display and the Dash® device with a display that was fixed on the cutting blocks. The time for adjustment of the tibial and femoral cutting blocks on knee models while using these devices was measured. A significant time reduction was demonstration when the Dash® device was used: The time reduction was 21% for the tibial block (p = 0.007), 40% for the femoral block (p < 0.001), and 32% for the whole procedure (p < 0.001). The integrated display, fixed on surgical instruments in a manner similar to a spirit level, seems to be more user-friendly for navigation beginners. Hence, unproductive time losses during the learning curve may be diminished.

Do residents perform TKAs using computer navigation as accurately as consultants?

The implantation of a total knee arthroplasty (TKA) is a milestone in a resident's surgical training. Studies demonstrate higher loosening rates after TKA by inexperienced surgeons. Alignment outliers should be avoided to achieve a long implant survival. Therefore, our study questioned whether residents implant knee prostheses using computer navigation as accurately as experienced consultants. The data for 662 consecutive TKAs were analyzed retrospectively. The operations were performed by 4 consultants (n=555) and 5 residents under supervision by a consultant (n=107). Cutting errors were recorded from the navigation data. The postoperative mechanical axis and operation time were recorded. Operation time was significantly prolonged if residents performed the operation vs consultants (139 vs 122 minutes, respectively). The analysis of cutting errors within each surgeon's first 20 navigated operations resulted in no significant difference between residents and consultants. During the subsequent operations, a trend toward a more accurate placement of the prosthesis was detected for consultants. The rate of outliers with a mechanical axis deviation >2° was low and did not significantly differ between residents and consultants (3.7% vs 2.3%, respectively). Our study shows that residents implant their first TKA using computer navigation as accurately as experienced consultants. However, the residents' operations take longer and therefore incur additional costs for the teaching clinic.

How much tibial resection is required in total knee arthroplasty?

The purpose of our study was to calculate the optimal tibial resection depth in total knee arthroplasty. The data from 464 navigated total knee arthroplasties were analysed. An implant with a minimum insert thickness of 8 mm was used. Data regarding leg axis, joint line, insert thickness and tibial resection depth were recorded by the navigation device. An algorithm was developed to calculate the optimal tibial resection depth. The required tibial resection significantly correlates with the preoperative leg axis (p < 0.001). In valgus deformities the required resection depth averaged 5.1 mm and was significantly reduced compared to knees with a neutral leg axis (6.8 mm, p < 0.001) and varus deformities (8.0 mm, p < 0.001). Manufacturers recommend undercutting the high side of the tibial plateau to the depth of the thinnest insert available. However, our study demonstrates that in valgus deformities a reduced tibial resection depth is preferable. Hence, unnecessary bone loss can be avoided.

[Imageless computer navigation of hip resurfacing arthroplasty]. / Bildfreie Computernavigation von Hüftoberflächenersatzprothesen.

OBJECTIVE: Precise implantation of hip resurfacing arthroplasty by imageless computer navigation. Hence a malalignment of the femoral component, leading to early loss of the implant, can safely be avoided. INDICATIONS: Coxarthrosis in patients with normal bone mineral density; only minor deformity of the femoral head that enables milling around the femoral neck without notching. CONTRAINDICATIONS: Osteoporosis; large necrosis of the femoral head; metal allergy; small acetabular seat and corresponding wide femoral neck, leading to needless acetabular bone loss; pregnancy, lactation. SURGICAL TECHNIQUE: Hip joint exposure by a standard surgical approach, bicortical placement of a Schanz screw for the navigation array in the lesser trochanter. Referencing of the epicondyles, the four planes around the femoral neck and head by use of the navigation pointer. Planning of the desired implant position on the touchscreen of the navigation device; a guide wire is inserted into the femoral head and neck using the navigated drill guide; navigated depth drilling is performed. The femoral head is milled using the standard instruments. The acetabular bone stock is prepared with the conventional instrumentation; high-viscosity cement is finger-packed on the reamed head and the femoral component is inserted. Hammer blows should be avoided to prevent microfractures. Verification of the implant position by the navigation device; displacement of the Schanz screw; joint reposition and closure of the wound. POSTOPERATIVE MANAGEMENT: Standard postoperative management after hip arthroplasty. RESULTS: The comparison of 40 navigated and 32 conventionally implanted ASR prostheses resulted in a significant reduction of outliers by use of computer navigation (navigated procedures: one outlier, conventional procedure: nine outliers; p<0.001). Accuracy of the navigation device was tested by analysis of planned and verified implant position: CCD angle accuracy was 1 degrees , antetorsion accuracy was 1 degrees , and offset accuracy was 1.5 mm. An ongoing computed tomography-based anatomic study proved a varus-valgus accuracy of the navigation device of 1 degrees .

The effect of computer navigation on blood loss and transfusion rate in TKA.

The blood loss that accompanies total knee arthroplasty (TKA) can be substantial. Many patients need perioperative blood transfusions. To avoid anemia and transfusion-related complications, the amount of blood loss and need for blood transfusions must be reduced. If standard jig instruments are used, an opening of the femoral medullary canal is required. This operative step has been recognized as a reason for elevated blood loss; it is not required if computer navigation is used. Hence, the purpose of this study was to investigate the effect of computer navigation on blood loss and transfusion rate in TKA. The data of 500 consecutive patients undergoing TKA were analyzed, and patient- and operation-related data and blood loss and transfusion rates were recorded. The total blood loss was calculated by use of the Orthopedic Surgery Transfusion Hemoglobin European Overview (OSTHEO) formula. The average blood loss in the drainages (standard procedures, 880 mL; navigated procedures, 761 mL; P=.001) and the calculated total blood loss (standard procedures, 1375 mL; navigated procedures, 1242 mL; P=.036) were significantly reduced in the navigation group. The transfusion rate of navigated procedures was almost halved (standard procedures, 0.23 transfusions/patient; navigated procedures, 0.12 transfusions/patient; P=.035). Our study demonstrated a reduced blood loss if TKAs were implanted by use of computer navigation. The diminished blood loss resulted in a 50% reduction of allogenic blood transfusions. Hence, computer navigation may be attractive for patients with a high risk of transfusions or uncommon blood groups. Prospective studies are required to verify this potential benefit of computer navigation.

Is referencing the posterior condyles sufficient to achieve a rectangular flexion gap in total knee arthroplasty?

Femoral malrotation in total knee arthroplasty causes flexion gap instability. Conventional instruments mostly reference the posterior condylar angle (PCA). The aim of this study was to verify whether the computer-navigated flexion gap (GAP) method produces a rectangular flexion gap and if a balanced flexion gap could also be achieved by referencing the PCA. A total of 100 knee prostheses were analysed using the navigated GAP method, and flexion gap symmetry along with femoral rotation were recorded. The GAP technique resulted in a rectangular flexion gap with adequate femoral rotational alignment. If the PCA technique had been used, only 51% of the femoral components would have been implanted in correct femoral rotation; the remaining 49% would have implanted with flexion gap instability. The GAP technique produces a rectangular flexion gap. The referencing of the PCA was shown to be less reliable. Thus, modern knee prosthesis instrumentation should not base femoral rotation solely on the PCA.