Femoral Preparation Research Articles

The Femur-First Technique for Oxford Medial Unicompartmental Knee Arthroplasty.

The Femur-First Technique for Oxford Medial Unicompartmental Knee Arthroplasty.

Femoral Preparation Before Head Dislocation in Hip Hemiarthroplasty for Fractured Neck of Femur Saves Time and Keeps the Acetabulum Clean of loose bone fragments: A Retrospective Study and Technical Report

Introduction: Femoral neck fractures are the most common traumatic injuries associated with increasing age and osteoporosis, occurring most in older females. The femoral neck is under constant strain from externally and internally generated forces, approximately 500 – 200 micro-strains from daily activities. Common causes are falls in the elderly and road traffic accidents in younger patients. There is a significant in-house mortality and one-year mortality rate associated with femoral fractures. Fractures can be classified using the Garden Classification or the 2018 AO/OTA classification. Management includes open reduction and internal fixation, cannulated or sliding screws and hemiarthroplasty or total hip arthroplasty. This study examines the benefits of femoral preparation before head dislocation in hip hemiarthroplasties by assessing differences between pre-operative and post-operative haemoglobin levels and surgical times. Methods: We report the surgical techniques of hip hemiarthroplasty where the femur is prepared before the femoral head is removed and the hip is reduced in the flexion position. A retrospective review of electronic patient records of patients who underwent hemiarthroplasties from June 2022 to June 2023 was conducted. Results: Surgical times for this surgical technique were 30 minutes faster than traditional methods while the differences in haemoglobin levels were minimal. Conclusion: Longer surgical times are associated with adverse events such as infections and wound dehiscence while increasing risks via surgeon fatigue and longer anaesthesia durations. Innovations in surgical techniques should thus aim to minimise surgical time without compromising procedures. This technique saves 30 min on average while having similar levels of blood loss to traditional techniques, maintaining standards, and not compromising on patient safety. Femoral preparation before dislocating the femoral head reduces the steps taken in leg repositioning which saves time and effort by the assistant. The reduction technique also avoids any risk of intra-operative iatrogenic fracture that can happen, especially if the assistant is a junior surgeon who lacks experience with hip reduction.

Does Automated Impaction Improve Femoral Component Sizing and Alignment in Total Hip Arthroplasty?

BackgroundWhile automated impaction can provide a more standardized process for femoral canal preparation, little is known regarding its effect on femoral component sizing and position. The purpose of our study was to directly compare femoral component canal fill ratio (CFR) and coronal alignment between primary total hip arthroplasty (THA) procedures performed with automated impaction versus manual mallet impaction. MethodsA retrospective analysis was performed on 184 patients who underwent primary THA by a single arthroplasty surgeon between 2017 and 2021 with a modern cementless femoral component using either the direct anterior or posterolateral approach. The final cohort was divided into 2 groups based on impaction technique during broaching: automated (N = 122) or manual (N = 62). A propensity score match was used to match for age, body mass index, sex, high versus standard offset stem, and preoperative femoral bone quality. Radiographic review was performed to measure intramedullary prosthetic CFR and coronal alignment. ResultsThe automated cohort trended toward the use of a larger stem (5.67 versus 4.82, P = .006) and had a larger CFR at all 4 levels within the proximal femur (P = .004). The automated cohort had a more valgus and reliable coronal alignment (−0.57 (SD 1.50) versus −0.03 (SD 2.17) degrees, P = .03) and significantly shorter operative time (mean 78 versus 90 minutes, P < .001). There were no intraoperative or postoperative periprosthetic fractures in either cohort. ConclusionAutomated impaction in primary THA is a safe technique for femoral preparation, which resulted in improved stem coronal alignment, optimized canal fill within the proximal femur, and reduced operative times.

Cementation in total hip arthroplasty: history, principles, and technique.

Total hip arthroplasty (THA) is a remarkably successful operation that has grown rapidly its utilization. Early modern THA constructs as developed by Sir John Charnley featured cemented femoral stems and acetabular components. The technique of cementing components for THA has evolved over time. Modern acetabular preparation requires exposure of the subchondral bone with appropriate cement penetration into the trabecular bone, whereas femoral preparation requires cleaning of the canal, cement restrictor placement, retrograde filling, and pressurization of the cement. When used appropriately, these techniques result in excellent long-term survivorship of implants and are also widely considered to be the ideal method of fixation for hip fractures. The purpose of this article to review the history, properties, techniques, and outcomes of bone cement utilization in THA.

Safe femoral condyle range for the reverse Rigidfix femoral fixation device in anterior cruciate ligament reconstruction

BackgroundTo determine the characteristics of cross-pin protrusion in patients treated with the reverse Rigidfix femoral fixation device for femoral tunnel preparation through the anteromedial portal in Arthroscopic anterior cruciate ligament reconstruction (ACLR), analyse the reasons for this outcome, and identify safety hazards of this surgical technique for improvement.MethodsA retrospective analysis of patients who underwent ACLR using this technology at our hospital in 2018 was conducted. Patients with and without cross-pin protrusion were included in the protrusion positive and negative groups, respectively. The sex, age and imaging characteristics of the patients with cross-pin protrusion were identified, and the reasons for cross-pin protrusion were analysed.ResultsThere were 64 and 212 patients in the protrusion positive and negative groups, respectively. The proportion of cross-pin protrusion cases was 23.19% (64/276). There was a significant difference in the ratio of males to females (P < 0.001, χ2 = 185.184), the mediolateral femoral condyle diameter (protrusion positive group, 70.59 ± 2.51 mm; protrusion negative group, 82.65 ± 4.16 mm; P < 0.001, t = 28.424), and the anteroposterior diameter of the lateral femoral condyle (protrusion positive group, 58.34 ± 2.89 mm; protrusion negative group, 66.38 ± 3.53 mm; P < 0.001, t = 16.615). The cross-pins did not penetrate the lateral femoral condyle cortex in patients with a mediolateral femoral condyle diameter ≥ 76 mm, but the cross-pins definitely penetrated the cortex when the diameter was ≤ 70 mm. The cross-pins did not penetrate when the anteroposterior lateral femoral condyle diameter was ≥ 66 mm, but the cross-pins definitely penetrated it when the diameter was ≤ 59 mm.ConclusionThe patients with cross-pin protrusion after reverse Rigidfix femoral fixation treatment to prepare the femoral tunnel through the anteromedial portal in ACLR were mainly females with small femoral condyles. For patients with a mediolateral femoral condyle diameter ≥ 76 mm and an anteroposterior lateral femoral condyle diameter ≥ 66 mm, there is no risk of cross-pin protrusion, so this technique can be used with confidence.Levels of evidenceIII.

AAHKS Best Podium Presentation Research Award: Femoral Perforation During Direct Anterior Approach Total Hip Arthroplasty: Incidence, Cohort Characteristics, and Management

BackgroundCortical perforation during femoral preparation is a recognized complication of total hip arthroplasty (THA) but the incidence, patient characteristics, management, and outcome have not been described for the direct anterior approach (DAA). MethodsA database query of all primary and conversion DAA THAs performed by a single surgeon from 2009 to 2021 was used to identify hips that sustained a recognized intraoperative femoral perforation. Radiographs were used to assess stem subsidence, Dorr femur type, and Canal Flare Index. ResultsAmong 3,973 THAs, 16 patients (0.4%) sustained perforations during broaching including 8 males and 8 females with a mean age at surgery of 65.6 (range 41-81) years and a mean body mass index of 31.0 (range 19.0-44.4). Two hips were converted to longer primary cementless stems to bypass the perforation. For the remaining 14, the broach was redirected and the same primary stem was implanted. Limited weight-bearing (6 patients) or protected weight-bearing as tolerated with a walker/cane (10 patients) was advised postoperatively. At a mean follow-up of 18.7 (range 4-105) months, all stems were stable with no fractures, subsidence, or revisions. Factors associated with perforation included difficulty with exposure (body mass index >40 or a contracture), measurable osteoporosis (Canal Flare Index <3.0), and abnormal proximal femoral anatomy due to prior trauma, retained hardware, or Perthes disease. ConclusionIn this case series, isolated perforation of an otherwise intact femur during DAA was successfully managed with redirection of the broach, implantation of a primary stem that achieved axial/rotational stability, and protected weight-bearing. Level of EvidenceIV, Case Series.

Variability in Femoral Preparation and Implantation Between Surgeons Using Manual and Powered Impaction in Total Hip Arthroplasty.

BackgroundThe influence of the surgical process on implant loosening and periprosthetic fractures (PPF) as major complications in uncemented total hip arthroplasty (THA) has rarely been studied because of the difficulty in quantification. Meanwhile, registry analyses have clearly shown a decrease in complications with increasing experience. The goal of this study was to determine the extent of variability in THA stem implantation between highly experienced surgeons with respect to implant size, position, press-fit, contact area, primary stability, and the effect of using a powered impaction tool.MethodsPrimary hip stems were implanted in 16 cadaveric femur pairs by three experienced surgeons using manual and powered impaction. Quantitative CTs were taken before and after each process step, and stem tilt, canal-fill-ratio, press-fit, and contact determined. Eleven femur pairs were additionally tested for primary stability under cyclic loading conditions.ResultsManual impactions led to higher variations in press-fit and contact area between the surgeons than powered impactions. Stem tilt and implant sizing varied between surgeons but not between impaction methods. Larger stems exhibited less micromotion than smaller stems.ConclusionsLarger implants may increase PPF risk, while smaller implants reduce primary stability. The reduced variation for powered impactions indicates that appropriate measures may promote a more standardized process. The variations between these experienced surgeons may represent an acceptable range for this specific stem design. Variability in the implantation process warrants further investigations since certain deviations, for example, a stem tilt toward varus, might increase bone stresses and PPF risk.

En bloc Extraction Technique in Total Hip Arthroplasty for Avascular Necrosis Treated with Non-vascular Fibular Autografts

Performing a total hip arthroplasty (THA) in the presence of a previous fibular graft can be technically challenging and may be associated with complications. We describe a novel method of “en bloc extraction” of the fibular graft during THA to facilitate complete removal of the graft and adequate femoral preparation. This en bloc extraction technique is safe and effective for complete removal of fibular graft during THA performed in patients with non-vascularized fibula grafting for avascular necrosis.

TIBIAL PHYSEAL RESPECTING TUNNEL DRILLING TECHNIQUE FOR ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION IN SKELETALLY IMMATURE ATHLETES

Background:ACL reconstruction is common in young patients.Hypothesis/Purpose:To report outcomes of a novel tibial drilling technique using an inside-out socket drilling method, with a drill pin and epiphyseal socket drilling in skeletally immature patients. Minimizing disruption to the tibial physis, attempting to prevent growth disturbance with an anatomic ACL that eliminates the graft bend angle at the tibial tunnel.Methods:We used a standard all-epiphyseal drilling technique for femoral preparation. The tibial drill guide, set at 55° for our tibial physeal respecting approach, is positioned in the posterior third of the ACL footprint in-line with the posterior aspect of the lateral meniscus anterior root. The FlipCutter (Arthrex Inc., Naples, FL) is drilled from the external proximal tibia. Thus, only a 3.5mm diameter tunnel crosses the proximal tibial physis. With the FlipCutter deployed, the cutting radius is checked to confirm proper position without risk of damage to the meniscal root, PCL, or articular cartilage. With fluoroscopic guidance, the tibial socket is drilled from the intra-articular surface towards the physis, stopping proximal to the physis. This results in a 15 to 20 mm all-epiphyseal socket length. We collected demographics, re-tear rate, physeal arrest (partial/complete), and patient reported outcomes in order to understand potential problems and mid-term outcomes of this procedure.Results:Eight male patients were included in the study (average age=10.6±1.5 years). All patients had radiographs >6months post-surgery, and no patient had a clinically significant leg length discrepancy (>2cm) or deformity. The two patients followed >24months post-operatively were cleared to return to sports by one year. No patients demonstrated a positive Lachman or pivot shift test at >6months follow-up. No Patients had a ROM deficit at >6months follow-up. Five patients completed Pedi-IKDC and Lysholm assessments (time from surgery=16.2months+10.6months; range 7–28.8months). Average IKDC and Lysholm scores were 88+10 and 95+9, respectively. There were no graft ruptures in the cohort (average follow-up: 13.8months±8.9 months; range 6.8–30.6months).Conclusion:Our preliminary data from this novel tibial physeal respecting technique suggest it may be appropriate for skeletally immature patients with sufficiently large enough femoral epiphyses to hold a 10mm graft tunnel without disturbance to the physis. This technique seems successful in terms of graft survival, patient reported outcomes, and no growth disturbance within 2 years of surgery, although we recognize our small sample size as a limitation. Further studies will better evaluate long-term outcomes of this pediatric ACLR technique.

Pneumatic femoral broaching in direct anterior approach hip arthroplasty

AimThe aim of this study is to report the safety and efficacy of the Woodpecker pneumatic broaching system in direct anterior hip arthroplasty.Methods649 primary elective anterior bikini total hip arthroplasties...

Use of a patella clamp for femoral head allograft preparation.

Use of a patella clamp for femoral head allograft preparation.

Pneumatic high-speed burr as an adjunct to femoral preparation for fixation of bisphosphonate related fractures.

Pneumatic high-speed burr as an adjunct to femoral preparation for fixation of bisphosphonate related fractures.

Three-dimensional-printed custom guides for bipolar coxofemoral osteochondral allograft in dogs.

The objective of this experimental study was to develop and evaluate a three-dimensionally printed custom surgical guide system for performing bipolar coxofemoral osteochondral allograft transplantation in dogs. Five cadaver dogs, weighing 20-38 kg were used in the study. Custom surgical guides were designed and three-dimensionally printed to facilitate accurate execution of a surgical plan for bipolar coxofemoral osteochondral allograft transplantation. Guide-assisted technique was compared to freehand technique in each cadaver. Surgical time was recorded and postoperative computed tomography and three-dimensional segmentation was performed. Femoral version and inclination angles, femoral neck length, and gap present at the femoral and acetabular donor-recipient interface was compared between the virtual surgical plan and postoperative outcome for both techniques. One-tailed paired t-test (P < .05) was used for statistical analysis. When compared to free-hand preparation, mean donor femoral preparation time was 10 minutes longer and mean recipient preparation time was 2 minutes longer when using guides (p = 0.011 and p = 0.001, respectively). No difference in acetabular preparation time was noted between groups. Gap volume at the acetabular and femoral donor-recipient interface was not different between groups. Mean difference between the planned and postoperative version angle was 6.2° lower for the guide group when compared to the freehand group (p = 0.025). Mean femoral neck length was 2 mm closer to the plan when using guides than when performing surgery freehand (p = 0.037). Accuracy for femoral angle of inclination was not different between groups. Custom surgical guides warrants consideration in developing bipolar coxofemoral osteochondral allograft transplantation as an alternative surgical technique for managing hip disorders in dogs.

Anteromedial Portal Reference Technique for Femoral Tunnel Depth Measurement During Arthroscopic Anterior Cruciate Ligament Reconstruction.

Femoral tunnel preparation during the anterior cruciate ligament reconstruction is a technically demanding step. The anteromedial (AM) portal technique necessitates knee hyperflexion during the femoral tunnel reaming. In a hyperflexed knee, the arthroscopic visualization of the laser markings on the femoral tunnel reamer becomes obscured. Thus, the calculation of the depth of the femoral tunnel becomes difficult. Our technique helps in femoral tunneling reliably without the need for arthroscopic visualization using the AM portal as a reference point to calculate the depth while drilling. This technique can be performed without the need for a second assistant to hold the arthroscope. Furthermore, this technique does not require any specific instruments, and there is no obligation for an additional incision.

Low pelvic incidence is a risk factor for intraoperative complications in minimally invasive anterolateral approach for total hip arthroplasty.

Minimally invasive anterolateral approach (ALA) has gained popularity in recent years as better postoperative functional recovery and lower risk of postoperative dislocation are claimed. However, difficulties for femur exposure and intraoperative complications during femoral canal preparation and component placement have been reported. This study analyses the effect of anatomical factors on difficulties for femoral access and intraoperative complications with a modified minimally invasive ALA. 310 consecutive patients who had primary unilateral total hip arthroplasty (THA) by single surgeon using same approach and technique, and being suitable for EOS were included. All patients underwent pre- and postoperative standing and sitting full-body EOS acquisitions and pelvic and femoral parameters were measured. All intra- and postoperative complications for femoral preparation and implantation were assessed. Intraoperative complications included femoral fractures and difficulties for femoral exposure. 10 patients (3.2%) had intraoperative femoral fractures (2 greater trochanter, 8 calcar). Difficult access to the proximal femur was reported for 10 other patients (3.2%). Patients with intraoperative complications presented a significantly lower pelvic incidence (PI) than patients without intraoperative complications (mean PI: 39.4° vs. 56.9°, p < 0.001). The pelvic incidence can be useful to detect anatomically less favourable patients for THA implantation using ALA.

Morphology of the Greater Trochanter: An Assessment of Anatomic Variation and Canal Overhang

BackgroundVarus malposition is a risk of early failure in total hip arthroplasty. The degree to which the tip of the greater trochanter (GT) overhangs the canal can increase this risk. Although we know proximal femoral anatomy is variable, no study has addressed variations in medial overhang of the GT on plain radiographs. MethodsAll low anteroposterior pelvis radiographs more than 1 year were reviewed 3 times by 2 orthopaedic surgeons and one radiologist. The canal width (CW) was measured 10 cm below the lesser trochanter. Canal overhang (CO) was defined by the distance between the lateral medullary canal and a parallel line beginning at the most medial aspect of the GT. The overhang index (OI) is defined as the percentage of the canal overhung by the GT. ResultsThe mean CW was 13.5 mm, mean CO 16.4 mm, and mean OI 1.22. Hips were then classified as the following: (A) OI < 0.5 (n = 8), (B) OI 0.5-1.0 (n = 78), (C) OI 1.0-1.5 (n = 191), and (D) OI > 1.5 (n = 68). Intraobserver reliability was excellent for all measures: 0.89 (confidence interval: 0.87-0.91) for CW, 0.96 (0.95-0.97) for CO, and 0.97 (0.97-0.98) for OI. Interobserver reliability was good for CW 0.75 (0.70-0.79) and excellent for CO 0.90 (0.88-0.92) and OI 0.95 (0.94-0.96). ConclusionsVariations in the morphology of the proximal femur can predispose to varus component malposition. The degree to which the GT overhangs the canal can be quantified and classified based on plain films. This can aid in preoperative planning and help guide intraoperative proximal femoral preparation.

Three-step technique for implantation of rotating hinge knee prostheses : Demonstration using the Enduro prosthesis.

Implantation of an axis-guided knee prosthesis with consideration of the joint line and balanced flexion and extension gap to reduce the mechanical load on the prosthesis axis and to improve the movement of the prosthesis. Distinct unilateral instability due to ligament insufficiency in association with knee prostheses. Primary implantation of axis-guided knee prostheses with pronounced axial malalignment (>20-25° valgus or varus malalignment) or/and severe flexion contracture > 40°. Replacement of prosthesis with nonsignificant imbalance between flexion and extension gap. Clearly unstable flexion gap such that the extension gap cannot be adjusted appropriately. Significant femoral bone defects requiring distal femoral replacement prostheses. Reconstruction of the tibial platform with the trial prosthesis with regard to height in relation to the tip of the fibula. Determination of the femoral prosthesis size. Adjustment of the anteroposterior (AP) cutting block of the selected size, referenced anteriorly and in correct rotation. Determination of the flexion gap with spacers using the stable side of the collateral ligaments. Positioning the distal cutting block and determination of the height of the extension gap. Moving the distal cutting block until the same height of spacer as used in the flexion gap fits into the extension gap, taking into account the stable side of the collateral ligaments. The extent of the displacementD1 is noted. Reverse displacement of the distal cutting block by the distanceD2 until asatisfactory bony contact surface for the femoral component in the distal femur can be created. The thickness of the required distal augments on the following chamfer-cutting guide (4-in‑1 cutting block) and thus on the femoral prosthetic component is the sum of D1 + D2. The chamfer-cutting guide (4-in‑1 block) with distal augments of the calculated height (D = D1 + D2) is placed in position. Definition and preparation of the posterior contact surface with positioning of any necessary posterior augments. Completion of the femoral preparation taking into account the distal and posterior augments. Assembly of the trial prostheses with atrial inlay having the height of the spacers used. Implantation of the selected prosthesis components. Thrombosis prophylaxis, physiotherapy under full weight-bearing and mobility exercises. After implantation of 104 axis-guided Enduro™ knee prostheses (Aesculap AG, Tuttlingen, Germany) (73knee prosthesis revisions and 31 primary implantations), the Knee Society Score increased from 42.8 ± 18.8 preoperatively to 84.8 ± 13.9 after 24months. Complications comprised one deep vein thrombosis and one periprosthetic infection.

Multimodal prophylaxis in patients with a history of venous thromboembolism undergoing primary elective hip arthroplasty.

We studied the safety and efficacy of multimodal thromboprophylaxis in patients with a history of venous thromboembolism (VTE) who undergo total hip arthroplasty (THA) within the first 120 postoperative days, and the mortality during the first year. Multimodal prophylaxis includes discontinuation of procoagulant medications, VTE risk stratification, regional anaesthesia, an intravenous bolus of unfractionated heparin prior to femoral preparation, rapid mobilization, the use of pneumatic compression devices, and chemoprophylaxis tailored to the patient's risk of VTE. Between 2004 to 2018, 257 patients with a proven history of VTE underwent 277 primary elective THA procedures by two surgeons at a single institution. The patients had a history of deep vein thrombosis (DVT) (186, 67%), pulmonary embolism (PE) (43, 15.5%), or both (48, 17.5%). Chemoprophylaxis included aspirin (38 patients), anticoagulation (215 patients), or a combination of aspirin and anticoagulation (24 patients). A total of 50 patients (18%) had a vena cava filter in situ at the time of surgery. Patients were followed for 120 days to record complications, and for one year to record mortality. Postoperative VTE was diagnosed in seven patients (2.5%): DVT in five, and PE with and without DVT in one patient each. After hospitalization, three patients required readmiss-ion for evacuation of a haematoma, one for wound drainage, and one for monitoring of an elevated international normalized ratio (INR). Seven patients died (2.5%). One patient died five months postoperatively of a PE during open thrombectomy. She had discontinued anticoagulation. One patient died of a haemorrhagic stroke while receiving Coumadin. PE or bleeding was not suspected in the remaining five fatalities. Multimodal prophylaxis is safe and effective in patients with a history of VTE. Postoperative anticoagulation should be prudent as very few patients developed VTE (2.5%) or died of suspected or confirmed PE. Mortality during the first year was mostly unrelated to either VTE or bleeding. Cite this article: Bone Joint J 2020;102-B(7 Supple B):71-77.

Adjustiertes mechanisches Alignment: Operative Technik – Tipps und Tricks

Mechanical alignment (MA) is astandardized procedure that aims to achieve aneutrally aligned leg axis. An alignment of the prosthesis closer to the patient's anatomy can be an approach for better clinical outcomes. The surgical technique of adjusted mechanical alignment (aMA) presented here is amodified extension-gap-first technique that takes into account the natural ligamentous tension of the knee joint so that ligamentous releases can be avoided as far as possible. The aMA technique can be used for primary and secondary varus gonarthrosis of up to20° of varus. The aim of the operation is to achieve abalanced ligament tension through afemoral osseous correction rather than ligament releases. TEA and the sulcus line are marked to control the ligament-based femoral rotation. The osteophytes are removed to ensure areliable ligament tension. Aquantitative ligament tensioner is stretched with great care, and gap width as well as medial and lateral ligament tension are read off. In order to correct an extension gap asymmetry, instead of the typical medial soft tissue release, the asymmetry is compensated by aspecial femoral cutting block. Now, the flexion gap is assessed, whereby the transverse femoral rotation follows the soft tissue tension. The tensioner adjusts arectangular flexion gap with balanced ligament tension. After a final balancing of the gaps, the femoral preparation is completed and the trial components are inserted. Here, the rotation of the tibial component is set by repeated flexion-extension cycles. The technique presented combines ameasured-resection technique with individual ligament tension. The maximum deviation of the femoral alignment in the coronal plane from the neutral alignment is2.5°. In order to avoid problems, it is recommended, as with the described technique, to achieve acomponent alignment based on the patient anatomy by adjusting the femoral component. The measured-resection technique carries the risk of flexion instability. With the gap-balancing technique symmetrical ligament tension can be achieved, assuming precise proximal tibial cuts. When aligning the femoral component rotation, flexion gap stability and patella tracking should be considered. Long-term studies of high case numbers are necessary to evaluate the good short-term results of the presented surgical technique.

A novel extramedullary technique to guide femoral bone preparation in mobile unicompartmental knee arthroplasty based on tibial cut and overall alignment

BackgroundThe mobile Oxford unicompartmental knee arthroplasty (UKA) implant has been widely used with an intramedullary guide for femoral preparation. We modified the femoral guide technique based on the tibial cut first and spacer block technique. This study was performed to determine the radiographic accuracy and early clinical outcomes of the extramedullary method.MethodsWe retrospectively evaluated 50 consecutive patients who underwent UKA using the extramedullary technique. An equal number of patients who underwent UKA with the conventional technique were matched as the control group. Clinical outcomes were evaluated in terms of the operating time, blood loss, range of motion, and Hospital for Special Surgery score. Radiographic accuracy was evaluated by the implant position and alignment in the coronal and sagittal planes.ResultsThe mean follow-up period was 39.76 ± 5.77 months. There were no differences in the postoperative Hospital for Special Surgery score, range of motion, or hip-knee-ankle angle between the two groups. The operating time in the extramedullary group was shorter than that in the conventional group (54.78 ± 7.95 vs. 59.14 ± 10.91 min, respectively; p = 0.025). The drop in hemoglobin after 3 days was only 12.34 ± 4.98 g/L in the extramedullary group which was less than that in the conventional group (p = 0.001). No significant differences were found in the postoperative coronal and sagittal angles between the two groups. Acceptable radiographic accuracy of the implant alignment and position was achieved in 92% of patients in the extramedullary group and 96% of patients in the conventional group.ConclusionsThe radiographic and clinical results of the extramedullary technique were comparable with those of the conventional technique with the advantage of no intramedullary interruption, less blood loss, a shorter operating time, and more rapid recovery. As the technique depends on the accurate tibial cut and overall alignment, we do not recommend it to surgeons without high volume experiences.Trial registrationRetrospectively registeredLevel of evidenceIV, retrospective study