[Chronic posttraumatic shoulder instability]. / Chronische posttraumatische Schulterinstabilität.

Chronic posttraumatic shoulder instability is characterized by trauma-associated, recurrent dislocations. Surgical treatment is indicated in most cases but it remains controversial how risk factors should be weighted to decide between arthroscopic Bankart repair (ABR), Latarjet or alternative procedures. Known risk factors for recurrence are patient age, hyperlaxity, sports profile and bone loss. Surgical techniques are discussed in detail. The ABR leads to high patient satisfaction and return to sports; however, in association with risk factors, recurrent dislocations are seen even several years later. Latarjet or bone block procedures lead to high patient satisfaction, sustainable stability as a revision procedure, but can also be primarily indicated for chronic instability depending on risk factors. Early complications are more frequent but of a minor nature in most cases. All techniques are known for a serious learning curve. If performed well, they do not seem to increase the risk of arthritis, which is most affected by the number of lifetime dislocations and higher energy trauma.

[Current aspects and new techniques in dislocation of the shoulder joint]. / Aktuelle Aspekte und neue Techniken bei Schultereckgelenksprengung.

With 12% of all injuries concerning the shoulder, acromioclavicular (AC) joint dislocations are a common injury especially in young and active patients. The Rockwood classification is widely accepted, which differentiates between six types depending on the degree of injury and the vertical dislocation. Because the classification does not adequately address the horizontal instability, its benefits are questionable and there is currently no consensus. For this reason, the classification and the therapy of these injuries are increasingly becoming the subject of scientific investigations. Whereas conservative treatment for type I and II injuries and operative treatment for type IV-VI injuries are widely accepted, there is still no agreement in treating type III lesions. The goal of this review article is to present the current evidence for the diagnostics, different classifications and therapeutic possibilities.

The biology of rotator cuff healing.

Despite advances in surgical reconstruction of chronic rotator cuff (RC) tears leading to improved clinical outcomes, failure rates of 13-94% have been reported. Reasons for this rather high failure rate include compromised healing at the bone-tendon interface, as well as the musculo-tendinous changes that occur after RC tears, namely retraction and muscle atrophy, as well as fatty infiltration. Significant research efforts have focused on gaining a better understanding of these pathological changes in order to design effective therapeutic solutions. Biological augmentation, including the application of different growth factors, platelet concentrates, cells, scaffolds and various drugs, or a combination of the above have been studied. It is important to note that instead of a physiological enthesis, an abundance of scar tissue is formed. Even though cytokines have demonstrated the potential to improve rotator cuff healing in animal models, there is little information about the correct concentration and timing of the more than 1500 cytokines that interact during the healing process. There is only minimal evidence that platelet concentrates may lead to improvement in radiographic, but not clinical outcome. Using stem cells to biologically augment the reconstruction of the tears might have a great potential since these cells can differentiate into various cell types that are integral for healing. However, further studies are necessary to understand how to enhance the potential of these stem cells in a safe and efficient way. This article intends to give an overview of the biological augmentation options found in the literature.

Inclination-dependent changes of the critical shoulder angle significantly influence superior glenohumeral joint stability.

BACKGROUND: The critical shoulder angle combines the acromion index and glenoid inclination and has potential to discriminate between shoulders at risk for rotator cuff tear or osteoarthritis and those that are asymptomatic. However, its biomechanics, and particularly the role of the glenoid inclination, are not yet fully understood. METHODS: A shoulder simulator was used to analyze the independent influence of glenoid inclination during abduction from 0 to 60°. Spindle motors transferred tension forces by a cable-pulley on human cadaveric humeri. A six-degree-of-freedom force transducer was mounted directly behind the polyethylene glenoid to measure shear and compressive joint reaction force and calculate the instability ratio (ratio of shear and compressive joint reaction force) with the different force ratios of the deltoid and supraspinatus muscles (2:1 and 1:1). A stepwise change in the inclination by 5° increments allowed simulation of a critical shoulder angle range of 20° to 45°. FINDINGS: Tilting the glenoid to cranial (increasing the critical shoulder angle) increases the shear joint reaction force and therefore the instability ratio. A balanced force ratio (1:1) between the deltoid and the supraspinatus allowed larger critical shoulder angles before cranial subluxation occurred than did the deltoid-dominant ratio (2:1). INTERPRETATION: Glenoid inclination-dependent changes of the critical shoulder angle have a significant impact on superior glenohumeral joint stability. The increased compensatory activity of the rotator cuff to keep the humeral head centered may lead to mechanical overload and could explain the clinically observed association between large angles and degenerative rotator cuff tears.

In vivo clinical and radiological effects of platelet-rich plasma on interstitial supraspinatus lesion: Case series.

BACKGROUND: Rotator cuff tear (RCT) is a frequent condition of clinical relevance that can be managed with a symptomatic conservative treatment, but surgery is often needed. Biological components like leukocytes and platelet rich plasma (L-PRP) could represent an alternative curative method for interstitial RCT. HYPOTHESES: It has been hypothesized that an ultrasound guided L-PRP injection in supraspinatus interstitial RCT could induce radiological healing. MATERIAL AND METHODS: A prospective case series including 25 patients was performed in order to assess the effect of L-PRP infiltration into supraspinatus interstitial RCTs. Primary outcome was tear size change determined by magnetic resonance imaging arthrogram (MRA) before and 6 months after L-PRP infiltration. Secondary outcomes were Constant score, SANE score, and pain visual analog scale (VAS) after L-PRP infiltration. RESULTS: Tear volume diminution was statistically significant (P=.007), and a >50% tear volume diminution was observed in 15 patients. A statistically significant improvement of Constant score (P<.001), SANE score (P=.001), and VAS (P<.001) was observed. In 21 patients, Constant score improvement reached the minimal clinical important difference of 10.4 points. DISCUSSION: We observed a statistically significant and clinically relevant effect on RCT size and clinical parameters after L-PRP infiltration. Such an important improvement of supraspinatus interstitial RCT with conservative management is uncommon, therefore intratendinous L-PRP infiltrations could have been beneficial. This encouraging result could pave the way for future randomized studies in order to formally determinate whether L-PRP infiltrations are a possible alternative to surgical treatment of interstitial RCT. LEVEL OF EVIDENCE: Prospective observational study; Level of evidence II.

Dynamic intraligamentary stabilization: novel technique for preserving the ruptured ACL.

PURPOSE: Replacement of the torn anterior cruciate ligament (ACL) with a transplant is today`s gold standard. A new technique for preserving and healing the torn ACL is presented. HYPOTHESIS: a dynamic intraligamentary stabilization (DIS) that provides continuous postinjury stability of the knee and ACL in combination with biological improvement of the healing environment [leucocyte- and platelet-rich fibrin (L-PRF) and microfracturing] should enable biomechanically stable ACL self-healing. METHODS: Ten sportive patients were treated by DIS employing an internal stabilizer to keep the unstable knee in a posterior translation, combined with microfracturing and platelet-rich fibrin induction at the rupture site to promote self-healing. Postoperative clinical [Tegner, Lysholm, International Knee Documentation Committee (IKDC), visual analogue scale patient satisfaction score] and radiological evaluation, as well as assessment of knee laxity was performed at 6 weeks, 3, 6, 12, and 24 months. RESULTS: One patient had a re-rupture 5 months postoperative and was hence excluded from further follow-ups. The other nine patients presented the following outcomes at 24 months: median Lysholm score of 100; IKDC score of 98 (97-100); median Tegner score of 6 (range 9-5); anterior translation difference of 1.4 mm (-1 to 3 mm); median satisfaction score of 9.8 (9-10). MRI showed scarring and continuity of the ligament in all patients. CONCLUSIONS: DIS combined with microfracturing and L-PRF resulted in stable clinical and radiological healing of the torn ACL in all but one patient of this first series. They attained normal knee scores, reported excellent satisfaction and could return to their previous levels of sporting activity. LEVEL OF EVIDENCE: Case series with no comparison group, Level IV.

Age, trauma and the critical shoulder angle accurately predict supraspinatus tendon tears.

BACKGROUND: The pathogenesis of full-thickness tears of the rotator cuff remains unclear. Apart from age and trauma, distinct scapular morphologies have been found to be associated with rotator cuff disease. The purpose of the present study was to evaluate whether a score formed using these established risk factors was able to predict the presence of a rotator cuff tear reliably. METHODS: We retrospectively assessed a consecutive series of patients with a minimal age of 40 years old, who had true antero-posterior (AP) radiographs of their shoulders, as well as a magnetic resonance (MR) gadolinium-arthrography, between January and December 2011. In all of these patients, the critical shoulder angle (CSA) was determined, and MR images were assessed for the presence of rotator cuff tears. Additionally, the patients' charts were reviewed to obtain details of symptom onset. Based on these factors, the so-called rotator cuff tear (RCT) score was calculated. RESULTS: Patients with full-thickness RCTs were significantly older and had significantly larger CSAs than patients with intact rotator cuffs. Multiple logistic regression, using trauma, age and CSA as independent variables, revealed areas under the curve (AUCs) for trauma of 0.55, for age of 0.65 and for CSA of 0.86. The combination of all three factors was the most powerful predictor, with an AUC of 0.92. CONCLUSION: Age, trauma and the CSA can accurately predict the presence of a posterosuperior RCT. LEVEL OF EVIDENCE: Level IV. Case series with no comparison groups.

[Structured assessment for orthopaedic patients - method, results, and diagnostic potential]. / Strukturierte Anamnese bei orthopädischen Patienten - Methode, Resultate und diagnostisches Potenzial.

BACKGROUND: Review of medical records demonstrates a moderate to low correlation (r = 0.57 to 0.22) between daily limitations and symptoms based upon patient history. This correlation could be improved with the ideal questionnaire which would assess patients using the same questions with the same response options in the same order. Therefore, a simple patient questionnaire for orthopaedic patients was developed and validated to assess 10 symptoms, 12 limitations of daily life and patients' well-being. The concept was to provide a universal questionnaire that could be used for all patients and provide the basis for a structured assessment that would then provide standardised and comparable patient information. Additional localisation of symptoms would allow a differential diagnosis. For example, pain in the groin/thigh while standing and walking may be caused by osteoarthritis of the hip or osteochondrosis of the lumbar spine. Further physical investigation and diagnostic imaging may lead to the diagnosis. PATIENTS AND METHODS: This method was employed as part of routine quality control from November 2006 to October 2008 by two orthopaedic surgeons in their outpatient clinic in a tertiary health care hospital. Structured assessment was performed in all patients regardless of their pathology (hip, knee, shoulder, cervical spine, lumbar spine, foot) or situation (before/after surgery, conservative therapy). The completeness, symptom score, daily limitation score, and well-being as well as the relationships between symptom score, daily limitation score, and well-being were calculated. Answers regarding walking capacity and effective walking capacity could be compared. Several patients with combined orthopaedic pathologies were closely analysed. RESULTS: Data of 2642 structured assessments in 1777 patients (957 women, 53.9 %) were evaluated. The average age was 64.4 years. The data completeness on the front page was 96.2 and 86.3 % on the back page. The mean value for symptoms (daily limitations) was 34.31 (27.45), and the median was 32.5 (25.0). The distributions of the symptom score and daily limitation score were asymmetrical; 80 % of the patients were below 50 and 38, respectively. Well-being was excellent in 21.4 %, good in 24 %, moderate in 24.2 %, poor in 11.4 %, and very poor in 16.7 %. The main symptom was pain on movement/walking, with an average of 60.32. The symptom score, daily limitation score, and well-being were found to have a correlation to each other (Spearman's r between 0.55 and 0.63). Thirty-nine patients reported an inability to walk, although 36 could walk in the office (1 had paraplegia and 2 had paraparesis caused by lumbar stenosis). Combined pathologies in orthopaedic patients were found for cervical-shoulder, lumbar-hip, and lumbar-knee pathologies. CONCLUSIONS: A routine structured assessment can be performed with extra effort. A structured assessment provides patient information in a standardised form so that such information can be compared as well as allow a differential diagnosis. It is possible that answers to the questionnaire represent patients' subjective assessment rather than reality.

[Relative effect per patient (REPP)--outcome groups for total hip replacement and total knee replacement]. / Relativer Effekt pro Patient (REPP)--Ergebnisgruppen am Beispiel der Hüfttotalendoprothese und Knietotalendoprothese.

BACKGROUND: The outcome of orthopaedic surgery such as total hip replacement (THR) or total knee replacement (TKR) is commonly given by the change in mean scores on patient-reported outcome measures (Prom's). This may give the impression that all enrolled patients have experienced an improvement. But the Swedish hip registry and other studies report a reduction of complaints in 80-85 % of patients ("responders"), with the remainder (approximately one in six) remaining unchanged or reporting worse complaints ("non-responders"). According to Cohen, the degree of success in the "responders" group can be subdivided into excellent, good and moderate. For a given treatment, a total of 5 different outcome groups can therefore be defined: excellent, good, moderate, unchanged and worse. Allocation to the groups is based on the "relative effect per patient" (REPP). The REPP is calculated as the base-line score minus the post-treatment score divided by the baseline score. The maximum possible REPP is 1; a REPP of 0 means no effect and a negative REPP means deterioration. Allocation to the outcome groups is as follows: excellent 0.95 to 1 REPP, good 0.5 to 0.95 REPP, moderate over 0.2 to 0.5 REPP, unchanged -0.2 to 0.2 REPP and worse below -0.2 REPP. PATIENTS AND METHODS: Our local arthroplasty register was used to evaluate the 1-year outcomes of THR and TKR patients operated between March 2003 and November 2008, using WOMAC scores and EuroQoL scores. Only patients with complete data sets and unilateral THR/TKR were included. The success rate given by the REPP method was compared with that of the "responder rate" method defined by the OMERACT-OARSI criteria. RESULTS: With the WOMAC questionnaire, outcomes were as follows (THR/TKR): excellent 29/14 %, good 51/54 %, moderate 11/13 %, unchanged at 5/12 %, worse 4/7 %. The corresponding values for the EuroQoL were (THR/TKR): excellent 16/6 %, good 41/42 %, moderate 25/28 %, unchanged 12/16 %, worse 6/8 %. For THR, success rates were 92 % using the "responder rate" method (OMERACT-OARSI criteria) and 91 % using the REPP method with the WOMAC. CONCLUSION: Calculation of the REPP and the subsequent allocation to outcome groups is simple. The distribution of outcomes depends on the intervention (THR results better than TKR) and the patient questionnaire used (better results with a condition-specific than a generic questionnaire). The proportion of "unchanged" and "moderate" outcomes was greater with the generic questionnaire than with the condition-specific questionnaire, while the proportion of "worse" outcomes was similar for the two instruments. Partitioning of the degree of success into sub-groups, based on the REPP, provides more information for both the patient and the orthopaedic surgeon.

Distal radius attachments of the radiocarpal ligaments: an anatomical study.

Background Understanding the anatomy of the ligaments of the distal radius aids in the surgical repair of ligamentous injuries and the prediction of intraarticular fracture patterns. Purposes (1) to measure the horizontal and vertical distances of the origins of the radiocarpal ligaments from the most ulnar corner of the sigmoid notch and the joint line, respectively; and (2) to express them as a percentile of the total width of the bony distal radius. Methods We dissected 8 cadaveric specimens and identified the dorsal radiocarpal, radioscaphocapitate, and the long and short radiolunate ligaments. Results The dorsal radiocarpal ligament attached from the 16th to the 52nd percentile of the radial width. The radioscaphocapitate ligament attached around the radial styloid from the 86th percentile volarly to the 87th percentile dorsally. The long radiolunate ligament attached from the 59th to the 85th percentile, and the short radiolunate ligament attached from the 14th to the 41st percentile. Discussion There was a positive correlation between the radial width and the horizontal distance of the ligaments from the sigmoid notch. These findings may aid individualized surgical repair or reconstruction adjusted to patient size and enable further standardized research on distal radial fractures and their relationship with radiocarpal ligaments.

[Influence of chronic, structural changes of the muscle-tendon unit on the indication and technique of rotator cuff reconstruction]. / Einfluss chronisch-struktureller Veränderungen der Muskelsehneneinheit auf Indikation und Technik der Rotatorenmanschettenrekonstruktion.

Rotator cuff lesions are common and the incidence increases with age. After tendon rupture of the rotator cuff, the muscle-tendon unit retracts, which is accompanied by muscle fatty infiltration, atrophy, and interstitial fibrosis of the musculature, thus, fundamentally changing the muscle architecture. These changes are important prognostic factors for the operative rotator cuff reconstruction outcome. Selection of the correct time point for reconstruction as well as the optimal mechanical fixation technique are decisive for successful attachment at the tendon-to-bone insertion site. Thus, knowledge of the pathophysiological processes plays an important role. The goal of this article is to establish a relationship between currently existing evidence with respect to the preoperatively existing changes of the muscle-tendon unit and the choice of the time for the operation and the operative technique.

Biologically based strategies to augment rotator cuff tears.

Lesions of the rotator cuff (RC) are among the most frequent tendon injuries. In spite of the developments in both open and arthroscopic surgery, RC repair still very often fails. In order to reduce the failure rate after surgery, several experimental in vitro and in vivo therapy methods have been developed for biological improvement of the reinsertion. This article provides an overview of the current evidence for augmentation of RC reconstruction with growth factors. Furthermore, potential future therapeutic approaches are discussed. We performed a comprehensive search of the PubMed database using various combinations of the keywords "tendon," "rotator cuff," "augmentation," "growth factor," "platelet-rich fibrin," and "platelet-rich plasma" for publications up to 2011. Given the linguistic capabilities of the research team, we considered publications in English, German, French, and Spanish. We excluded literature reviews, case reports, and letters to the editor.

[Periprosthetic joint infections - a review for general practitioners]. / Protheseninfektionen - Eine Übersichtsarbeit für die Praxis.

The number of prosthetic joint implantation is continuously increasing. Periprosthetic joint infection is a rare but serious complication. The correct diagnosis is essential for successful treatment. It requires the close collaboration between general practitioners, orthopaedic surgeons and infectious disease specialists. A delayed diagnosis sets hurdles to the medical and surgical treatment. Also, antimicrobial treatment without proper microbiological sampling must be avoided. Swabs from wounds are not helpful, because the results represent the skin flora, but not the causative pathogen of infection. The general practitioner is the first physician that patients contact and has, therefore, a central role in diagnosing and managing periprosthetic joint infections. In this review, classification, diagnostic means and treatment concepts of periprosthetic joint infections are presented.

Expression of atrophy mRNA relates to tendon tear size in supraspinatus muscle.

Skeletal muscle atrophy and fatty infiltration develop after tendon tearing. The extent of atrophy serves as one prognostic factor for the outcome of surgical repair of rotator cuff tendon tears. We asked whether mRNA of genes involved in regulation of degradative processes leading to muscle atrophy, ie, FOXOs, MSTN, calpains, cathepsins, and transcripts of the ubiquitin-proteasome pathway, are overexpressed in the supraspinatus muscle in patients with and without rotator cuff tears. We evaluated biopsy specimens collected during surgery of 53 consecutive patients with different sizes of rotator cuff tendon tears and six without tears. The levels of corresponding gene transcripts in total RNA extracts were assessed by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Supraspinatus muscle atrophy was assessed by MRI. The area of muscle tissue (or atrophy), decreased (increased) with increasing tendon tear size. The transcripts of CAPN1, UBE2B, and UBE3A were upregulated more than twofold in massive rotator cuff tears as opposed to smaller tears or patients without tears. These atrophy gene products may be involved in cellular processes that impair functional recovery of affected muscles after surgical rotator cuff repair. However, the damaging effects of gene products in their respective proteolytic processes on muscle structures and proteins remains to be investigated.

[A simple orthopaedic patient questionnaire to measure symptoms and disabilities--validation and experience]. / Ein einfacher orthopädischer Patientenfragebogen für die Messung von Beschwerden und Behinderungen (Pationnaire) - Validierung, Erfahrungen.

AIM: The aim of this study was to measure musculoskeletal symptoms and disabilities in a structured and objective manner. For this purpose, we have developed a simple patient questionnaire (Pationnaire). This includes the most important symptoms and signs of the entire musculoskeletal system including the vertebrae. METHODS: The questionnaire was tested for construct validity and reliability. The experiences were gathered in separate centres within an outcome study after total hip arthroplasty and routine consultations. RESULTS: Construct validity was tested in 71 patients by comparing the questionnaire answers with details given by personal interview. Concordance was total in 95 %, partial in 3 %, and inadequate in 2 % (older patients with poly-morbidity). Concordance was improved by discussion, completion and correction of questionnaire answers together with the patient. Participants required an average of 9.9 minutes to complete the questionnaire. The test-retest reliability of the Pationnaire yielded, compared to the SF-36, more questions with a higher intraclass correlation coefficient (ICC); the mean ICC for all Pationnaire questions was 0.76 versus 0.57 for the SF-36. The percentage of identical answers was between 69.7 % and 99.4 % with the Pationnaire and between 52.2 % and 96.8 % with SF-36. User experience showed that the questionnaire can be used for initial and differential diagnosis, for improved communication with the patient, and to measure outcome. The questionnaire proved valuable in the differential diagnosis of symptoms after endoprosthesis. Information on type and location are particularly valuable in differentiating mechanical, inflammatory or other causes. The questionnaire can be used for outcome measurements in endoprosthesis. In 66 patients, 6 months after total hip prosthesis, pain scores were reduced from 47.8 to 29.5, symptom scores from 30.8 to 11.6, and disability scores from 22.5 to 10.5 (all changes statistically significant, p < 0.05). CONCLUSION: The questionnaire reliably measures symptoms and disabilities in orthopaedic disease. Interactive collection of patient history renders it more objective. The questionnaire can be used in outpatient consultations, for initial and differential diagnosis, to improve communication, and to measure outcome.

[Visual circle scale (VCS)--a patient-friendly scale to measure pain compared to VAS and Likert scale]. / Visuelle Kreisskala (VCS)--eine patientenfreundliche Skala zur Schmerzmessung im Vergleich mit der VAS und Likert-Skala.

AIM: The visual analogue scale (VAS) and Likert scale (LS) are widely used but the patients might have difficulties to work with these scales and there might be errors in calculation. The visual circle scale (VCS) is a graphic construct with a simple grading to augment the understanding and ease for calculation. METHOD: This study compares the different scales in orthopaedic patients for pain assessment postoperatively. In addition, the scales were rated by the patients for simplicity, understanding and global rating. RESULTS: Included were 65 patients (40 women) with an average age of 66 years with 330 pain assessments and 65 questionnaire ratings. The average pain was LS 42.7, VAS 39.3, VCS 44. The correlation coefficients r (Spearman) between all scales were > 0.89 and the same held also for sensitivity for change. The VCS was the scale preferred by > 50 % of the orthopaedic patients to assess the pain. CONCLUSION: The VCS is able to measure pain comparably to the known scales (VAS, Likert scale). From the patients point of view it is the preferred scale to work with.

[Clinical results 2 years after total hip replacement (WOMAC/SF-36) and comparison with the normal population (SF-36)]. / Klinische Resultate 2 Jahre nach Hüfttotalendoprothese (WOMAC/SF-36) und Vergleich mit der Normbevölkerung (SF-36).

AIM: The aim of this study was to determine the outcome after total hip replacement (THR) with the WOMAC and the SF-36 as well as to identify the most responsive items and to elucidate the reasons for increased pain postoperatively. METHODS: 73 patients filled out the questionnaires preoperatively and 3, 6, 12, 24 months postoperatively. All mean subscales and the responsiveness for each question were calculated. The patients with increased pain postoperatively were reassessed. RESULTS: All WOMAC subscales and six of the eight SF-36 subscales showed significant improvements after THR (p < 0.05). The most responsive items were the pain and disability questions (SRM, ES > 1.5). Two patients with a higher pain score postoperatively had associated symptomatic degenerative lumbar spinal disease. CONCLUSIONS: The WOMAC and the SF-36 are valid measures of the outcomes of THR in their German translations and document the good results after THR. Two years after THR the patients reach the same health state compared to an age matched control group in the population. The WOMAC contains more questions of higher responsiveness than the SF-36. A higher pain score postoperatively may be caused by degenerative disease of the lumbar spine.

Is restricted femoral navigation sufficient for accuracy of total knee arthroplasty?

A total knee arthroplasty performed with navigation results in more accurate component positioning with fewer outliers. It is not known whether image-based or image-free-systems are preferable and if navigation for only one component leads to equal accuracy in leg alignment than navigation of both components. We evaluated the results of total knee arthroplasties performed with femoral navigation. We studied 90 knees in 88 patients who had conventional total knee arthroplasties, image-based total knee arthroplasties, or total knee arthroplasties with image-free navigation. We compared patients' perioperative times, component alignment accuracy, and short-term outcomes. The total surgical time was longer in the image-based total knee arthroplasty group (109 +/- 7 minutes) compared with the image-free (101 +/- 17 minutes) and conventional total knee arthroplasty groups (87 +/- 20 minutes). The mechanical axis of the leg was within 3 degrees of neutral alignment, although the conventional total knee arthroplasty group showed more (10.6 degrees ) variance than the navigated groups (5.8 degrees and 6.4 degrees , respectively). We found a positive correlation between femoral component malalignment and the total mechanical axis in the conventional group. Our results suggest image-based navigation is not necessary, and image-free femoral navigation may be sufficient for accurate component alignment.