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Purpose: To compare the long-term clinical results and complications of two revision strategies for patients with failed total disc replacements (TDRs)., Methods: In 19 patients, the TDR was removed and the intervertebral defect was filled with a femoral head bone strut graft. In addition, instrumented posterolateral fusion was performed (removal group). In 36 patients, only a posterolateral instrumented fusion was performed (fusion group). Visual analogue scale (VAS) for pain and Oswestry Disability Index (ODI) were completed pre- and post-revision surgery. Intra- and post-operative complications of both revision strategies were assessed., Results: The median follow-up was 12.3 years (range 5.3-24.3). In both the removal and fusion group, a similar (p = 0.515 and p = 0419, respectively) but significant decrease in VAS- (p = 0.001 and p = 0.001, respectively) and ODI-score (p = 0.033 and p = 0.013, respectively) at post-revision surgery compared to pre-revision surgery was seen. A clinically relevant improvement in VAS- and ODI-score was found in 62.5% and 43.8% in the removal group and in 43.5% and 39.1% in the fusion group (p = 0.242 and p = 0.773, respectively). Removal of the TDR was associated with substantial intra-operative complications such as major vessel bleeding and ureter lesion. The percentage of late reoperations for complications such as pseudarthrosis was comparable for both revision strategies., Conclusions: Revision of a failed TDR is clinically beneficial in about half of the patients. No clear benefits for additional TDR removal as compared to posterolateral instrumented fusion alone could be identified. Particularly, when considering the substantial risks and complications, great caution is warranted with removal of the TDR. These slides can be retrieved under Electronic Supplementary Material.

Purpose: As yet, there are no studies describing a relationship between radiographic subsidence after lumbar total disc replacement (TDR) and patient symptoms. To investigate if subsidence, in terms of penetrated bone volume or angular rotation over time (ΔPBV and ΔAR), is related to clinical outcome. To assess if subsidence can be predicted by position implant asymmetry (IA) or relative size of the TDR, areal undersizing index (AUI) on direct post-operative radiographs., Methods: Retrospective cohort study consists of 209 consecutive patients with lumbar TDR for degenerative disc disease. A three-dimensional graphical representation of the implant in relation to the bony endplates was created on conventional radiographs. Consequently, the PBV, AR, IA and AUI were calculated, direct post-operative (DPO) and at last follow-up (LFU). For clinical evaluation, patients with substantial pain (VAS ≥ 50) and malfunction (ODI ≥ 40) were considered failures., Results: At a mean follow-up of 16.7 years, 152 patients (73%) were available for analysis. In 32 patients, revision by spinal fusion had been performed. Both ΔAR (4.33° vs. 1.83°, p = 0.019) and ΔPBV (1448.4 mm 3 vs. 747.3 mm 3 , p = 0.003) were significantly higher in the failure-compared to the success-group. Using ROC curves, thresholds for symptomatic subsidence were defined as ΔPBV ≥ 829 mm 3 or PBV-LFU ≥ 1223 mm 3 [area under the curve (AUC) 0.723, p = 0.003 and 0.724, p = 0.005, respectively]. Associations between symptomatic subsidence and AUI-DPO ≥ 0.50 (AUC 0.750, p = 0.002) and AR-DPO ≥ 3.95° (AUC 0.690, p = 0.022) were found., Conclusion: Subsidence of a TDR is associated with a worse clinical outcome. The occurrence of subsidence is higher in case of incorrect placement or shape mismatch.

Purpose: Patient-specific instruments (PSI) are already widespread used in total knee arthroplasty (TKA). Either computed tomography (CT) scans or magnetic resonance imaging (MRI) scans are used pre-operatively to create jigs to guide resection during surgery. This study is a sequel of previous work that showed significantly more radiological outliers for posterior slope when CT-based guides were used. The aim of this study was to assess differences in revision rate and clinical outcome between the two groups at 2-year follow-up., Methods: At the 2-year follow-up, 124 patients were analysed in this prospective, randomised single-blind study. A survival analysis with revision of the TKA as endpoint was performed. Patients fulfilled four patient-reported outcome measurements (PROMs). Scores on the questionnaires were compared between both groups at the different follow-up visits., Results: At final follow-up, there was no significant difference in the survival rates of the CT- and MRI-based PSI surgery. Postoperatively, the PROMs significantly improved within each group compared with the pre-operative values. There were no significant differences for the PROMs between both groups at the 2-years follow-up., Conclusions: Although previous results showed more outliers regarding posterior slope for CT-based PSIs, no difference in revision rate or the outcome of PROMs was found at 2-year follow-up. Further research to determine what the influence is of radiological outliers on implant survival and clinical outcomes is necessary., Level of Evidence: I.

Background: Achieving an optimal limb alignment is an important factor affecting the long-term survival of total knee arthroplasty (TKA). This is the first study to look at the limb alignment and orientation of components in TKA using a novel image-free handheld robotic sculpting system., Methods: This case-controlled study retrospectively compared limb and component alignment of 77 TKAs performed with a robot (Robot-group) with a matched control group of patients who received conventional alignment with intramedular rods (Control group). Alignment and component positioning was measured on full-leg weight-bearing and standard lateral X-rays by two independent observers. The image-free handheld robotic sculpting system calculated the planned and achieved mechanical axis (MA). Outliers were defined as > 3° deviation from planned alignment., Results: Mean MA was 180.1° (SD = 1.9) in the Robot-group, compared to the Control group with a mean MA of 179.1° (SD = 3.1, p = 0.028). We observed 5 outliers (6%) in the Robot-group and 14 outliers (18%, p = 0.051) in the Control group. Fraction of outliers of the frontal tibial component was 0% in the Robot-group versus 8% in the Control group (p = 0.038). There were no other statistical differences regarding the implant positioning between both groups., Conclusion: The Robot-group showed significantly less outliers compared to the conventional technique. Whether these differences are clinically relevant is questionable and should be investigated on the long term. Randomized controlled trials with larger patient series will be needed in the future to confirm our preliminary results.

Background: The self-assessment section of the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASESq) is one of the most used patient-reported outcome measures for general shoulder problems. This study was performed to establish a valid Dutch version of the ASESq (ASESq-NL)., Materials and Methods: A clinical prospective, nonrandomized study was performed. Translation of the ASESq into Dutch was done following the guidelines of cross-cultural adaptation. Patients older than 17 years of age with shoulder problems were included. Patients who declined to participate or insufficiently completed questionnaires were excluded. For test-retest reliability analysis, the intraclass correlation coefficient (ICC) was calculated and an interval of 7-28 days between test and retest was set. Cronbach alpha was used to determine internal consistency. Dutch validated versions of the Shoulder Pain and Disability Index (SPADI) and 36-Item Short Form Health Survey (SF-36) were completed and compared with the ASESq-NL to evaluate construct validity using a Spearman rank correlation coefficient calculation., Results: A total of 92 patients were included. Test-retest reliability was excellent with an ICC of 0.82. The mean test-retest interval was 13 days (standard deviation 4.4). Internal consistency was good, with a Cronbach alpha of 0.83. Construct validity of the ASES questionnaire was good. All domains of the ASESq-NL had significant ( P < .05) correlations with the domains of the SPADI and the SF-36, except for the SF-36 domains stability with "physical function and energy" and "emotional well-being.", Conclusion: The Dutch ASES questionnaire is a valid and reliable tool for the evaluation of shoulder problems and is permissible for implementation into the Dutch health care system., (© 2019 The Authors.)

Purpose: The purpose of this multicentre prospective randomized controlled trial was to compare the survival rate and clinical outcome in total knee arthroplasty (TKA) after MRI-based patient-specific instruments (PSI) and conventional instruments 5 years after initial surgery., Methods: At a mean follow-up of 5.1 years (0.4), 163 patients (90.6%) with a mean age of 71.8 years (8.7) were analysed. A survival analysis with revision of the TKA as endpoint was performed. The Knee Society Score (KSS), evaluations on plain radiographs and patient-reported outcome measures (PROMs) were obtained preoperatively and at each FU., Results: At final follow-up, one TKA in the PSI- (1.2%) and 3 TKAs in the conventional group (3.8%) had undergone revision surgery (n.s.). No radiological abnormalities were noted at any time point. Postoperatively, the KSS and PROMs significantly improved within each group compared with the preoperative values. There were no clinically relevant differences for the KSS [PSI: 77.4, 9.8 (95% CI 75.0-79.7) vs. conventional: 77.3 10.5 (95% CI 74.9-79.8)] and the PROMs between both groups (n.s.) at 5 years follow-up., Conclusion: There is still a lack of reliable data on the survival of TKA and clinical evidence, when using PSI for TKA. Longer follow-up studies are, therefore, needed., Level of Evidence: I.

Background: Low-dose radiotherapy (LDRT) for pain reduction in osteoarthritis (OA) is a frequently used treatment in Germany and Eastern European countries. The evidence on the effects of LDRT on pain in patients with OA remains unclear. This study evaluated the effect of LDRT on pain in patients with severe OA of the hip or knee joint., Methods: This prospective study included a total of 16 joints in 12 patients (4 hips and 12 knees). The inclusion criteria were: patients older than 50 years, severe OA (Kellgren-Lawrence grade III-IV) of the hip or knee joint, patients not responding to conservative treatment and patients who are inoperable or not willing to undergo surgery. The joint was irradiated with a total dose of 6.0 Gray. The Numeric Rating Scale for pain (NRS-pain) and patient-reported outcome measures were obtained at pre-, 6, 13, 26, 39 and 52 weeks post-radiation. A decrease of two points on the NRS-pain was defined as clinical relevant., Results: The median age of the included patients was 74 years (range 58-89). In 50% of the joints (n = 8, 3 hip and 5 knee joints), a clinical relevant difference in pain at 6 weeks post-radiation was observed. This clinical relevant difference decreased to 25% at 52 weeks post-radiation., Conclusion: LDRT showed a clinical relevant pain relief at 6 weeks after radiotherapy. The long-term effect of LDRT, however, was limited. A randomized placebo-controlled trial is necessary to assess the effect of LDRT on pain in patients with OA of the hip or knee joint.

Purpose: Despite multimodal pain management and advances in anesthetic techniques, total knee arthroplasty (TKA) remains painful during the early postoperative phase. This trial investigated whether computer-assisted cryotherapy (CAC) is effective in reduction of pain and consumption of opioids in patients operated for TKA following an outpatient surgery pathway., Methods: Sixty patients scheduled for primary TKA were included in this prospective, double-blind, randomized controlled trial receiving CAC at 10-12 °C (Cold-group, n = 30) or at 21 °C (Warm-group, n = 30) during the first 7 days after TKA according to a fixed schedule. All patients received the same pre-, peri- and postoperative care with a multimodal pain protocol. Pain was assessed before and after every session of cryotherapy using the numerical rating scale for pain (NRS-pain). The consumption of opioids was strictly noted during the first 4 postoperative days. Secondary outcomes were knee swelling, visual hematoma and patient reported outcome measures (PROMs). These parameters were measured pre-, 1, 2 and 6 weeks postoperatively., Results: In both study groups, a reduction in NRS-pain after every CAC session were seen during the postoperative period of 7 days. A mean reduction of 0.9 and 0.7 on the NRS-pain was seen for respectively the Cold- (P = 0.008) and Warm-group (n.s.). A significant (P = 0.001) lower number of opioids were used by the Cold-group during the acute postoperative phase of 4 days, 47 and 83 tablets for respectively the Cold and Warm-group. No difference could be observed for secondary outcomes and adverse effects between both study groups., Conclusions: Postoperative CAC can be in added value in patients following an outpatient surgery pathway for TKA, resulting in reduced experienced pain and consumption of opioids during the first postoperative days.

Purpose: Patient-specific instrumentation (PSI) for unicompartmental knee arthroplasty (UKA) has been available for a few years. However, limited literature is available on this subject. Hence, the aim of this cohort study is to evaluate the 2 years' results of our first experiences with the use of PSI in UKA. It is hypothesised that there is no advantage in rate of adverse events and in radiological and functional outcomes in comparison to literature on the conventional method., Methods: This cohort included 129 knees of 122 patients, operated by one surgeon. Outcome measures were the rate of adverse events (AEs); implant position as determined on radiographs; the accuracy of the default and approved planning of the implant sizes and the patient-reported outcome measures (PROMs) preoperatively, and at 3, 12 and 24 months, postoperatively., Results: A total of 6 (4.9%) AEs were observed in this study, with 4 (3.3%) tibial fractures being the main complication. The mean postoperative biomechanical axis was 176.4° and in the majority of cases, the radiographic criteria, as determined by the manufacturer, were met. The tibial component showed 20 (16.4%) outliers in the sagittal and 3 (2.5%) outliers in the frontal plane. There were no outliers of the femoral component. For the femoral and tibial components, respectively, in 125 (96.9%) and 79 (61.7%) cases, there was an agreement between approved planning and implanted component size. All PROMs improved significantly after surgery., Conclusion: Tibial fracture was the most common AE, probably related to the transition from cemented to uncemented UKA. Perioperative modifications to the surgical technique were made in order to prevent this AE. Improvements should be made to the operation technique of the uncemented tibial plateau to obtain an adequate placement and at the same time reduce the risk for tibial fracture. The PSI technique was a reliable tool for the placement of the femoral component. Functional outcome was in line with literature on the conventional method. It is strongly recommended that the surgeon approves every preoperative plan, in order to optimise the accuracy during the PSI surgery., Level of Evidence: III.

Purpose: We wished to compare the outcome of two types of cemented and uncemented modern stem design implants after hemiarthroplasty, with both an Orthopaedic Data Evaluation Panel rating of 10A., Methods: This retrospective study compares data obtained from two centres, with a total study population of 655 (n = 393 cemented, n = 262 uncemented). Patients were matched at baseline for gender, age, surgery side, American Society of Anesthesiologists score, body mass index and pre-operative haemoglobin level. Outcome measurements were prosthesis-related complications, pre- and post-operative, with reoperation rate and mortality and other complications after 1 year, surgery time, blood loss and immobility at discharge., Results: There were no significant differences in mortality after 1 year, total other complications, immobility at the time of discharge and total prosthesis-related complications between both groups. Significantly more periprosthetic fractures and post-operative infections were seen in the uncemented group with significantly more reoperations compared to the cemented group. Significant differences were seen in cardiovascular complications, blood loss and surgery time in favour of the uncemented group., Conclusions: In consequence of the significant higher prosthesis-related complications (e.g. infections, periprosthetic fractures and reoperations) in the uncemented group in this study, we recommend cemented hemiarthroplasty in patients with a femoral neck fracture., Level of Evidence: Level III, Case Controlled Study.

Background: Malnutrition after hip fracture is associated with increased rehabilitation time, complications, and mortality. We assessed the effect of intensive 3 month nutritional intervention in elderly after hip fracture on length of stay (LOS)., Methods: Open-label, randomized controlled trial. Exclusion criteria: age < 55 years, bone disease, life expectancy < 1 year, bedridden, using oral nutritional supplements (ONS) before hospitalization, and cognitive impairment. Intervention: weekly dietetic consultation, energy-protein-enriched diet, and ONS (400 mL per day) for 3 months. Control: usual nutritional care. Primary outcome: total LOS in hospital and rehabilitation clinic, including readmissions over 6 months (Cox regression adjusted for confounders); hazard ratio (HR) < 1.0 reflects longer LOS in the intervention group. Secondary outcomes: nutritional and functional status, cognition, quality of life, postoperative complications (6 months); subsequent fractures and all-cause mortality (1 and 5 years). Effect modification by baseline nutritional status was also tested., Results: One hundred fifty-two patients were randomized (73 intervention, 79 control). Median total LOS was 34.0 days (range 4-185 days) in the intervention group versus control 35.5 days (3-183 days; plogrank = .80; adjusted hazard ratio (adjHR): 0.98; 95% CI: 0.68-1.41). Hospital LOS: 12.0 days (4-56 days) versus 11.0 days (3-115 days; p = .19; adjHR: 0.75; 95% CI: 0.53-1.06) and LOS in rehabilitation clinics: 19.5 days (0-174 days) versus 18.5 days (0-168 days; p = .82; adjHR: 1.04; 95% CI: 0.73-1.48). The intervention improved nutritional intake/status at 3, but not at 6 months, and did not affect any other outcome. No difference in intervention effect between malnourished and well-nourished patients was found., Conclusions: Intensive nutritional intervention after hip fracture improved nutritional intake and status, but not LOS or clinical outcomes. Paradigms underlying nutritional intervention in elderly after hip fracture may have to be reconsidered.

Purpose: Patient-specific instruments (PSIs) are already in relatively common use, and their post-operative radiographic results are equal to those for total knee arthroplasty (TKA) with conventional instrumentation. PSI use requires a preoperative MRI scan, CT scan, or a combination of MRI and a long-leg standing radiograph. However, there is no consensus as to which of these modalities, MRI or CT, is the preferred imaging modality when performing TKA with PSIs., Methods: This systematic literature review and meta-analysis studied the differences in alignment outliers between CT- and MRI-based PSI for TKA. A search of the Cochrane Database of Systematic Reviews, MEDLINE/PubMed and Embase was conducted, without restriction on date of publication. Only level I evidence studies written in English that included TKA with the use of MRI- and CT-based PSI were selected. A meta-analysis was then performed of the rate of outliers in the biomechanical axis and individual femoral and tibial component alignment. Where considerable heterogeneity among studies was present or the data did not provide sufficient information for performing the meta-analysis, a qualitative synthesis was undertaken., Results: Twelve randomized controlled trials, studying 841 knees, were eligible for data extraction and meta-analysis. MRI-based PSI resulted in a significantly lower proportion of coronal plane outliers with regard to the lateral femoral component (OR 0.52, 95% CI 0.30-0.89, P = 0.02), without significant heterogeneity (n.s.). There were no significant differences regarding the biomechanical axis or frontal femoral and individual tibial component alignment., Conclusion: This systematic review and meta-analysis demonstrate that alignment with MRI-based PSI is at least as good as, if not better than, that with CT-based PSI. To prevent for malalignment, MRI should be the imaging modality of choice when performing TKA surgery with PSI., Level of Evidence: I.

Purpose: Patients with an upper brachial plexus lesion can suffer from dysfunction, joint deformities and instability of the shoulder. The goal of this study was to determine pain, shoulder function, patient satisfaction and muscle strength in shoulder arthrodesis in patients with an upper brachial plexus lesion more than 15 years after surgery., Methods: We retrospectively studied 12 patients with a brachial plexus lesion of mean age 46 years (27-61). At a mean of 19.8 years (15.4-30.3) after shoulder arthrodesis, patient-reported outcome measures (PROMs), range of motion (e.g., active and passive), patient satisfaction, strength of the affected and non-affected side (e.g., maximum isometric strength in Newton in forward and retroflexion, ab- and adduction, internal and external rotation) and position of fusion were obtained. PROMS consisted of the Visual Analogue Scale (VAS; 0-100, 0 being painless) for pain and the Disabilities of the Arm, Shoulder and Hand Score (DASH; 0-100, 0 being the best score) for function., Results: At latest follow-up, the median VAS pain score was 49 (0-96) and 0 for, respectively, the affected and unaffected side. The DASH was 15 (8-46), meaning a reasonable to good function of the upper extremity. Active and passive retroflexion was significantly different (p = 0.028). All subjects stated that in the same situation they would undergo a shoulder arthrodesis again. The unaffected side was significantly stronger in every direction. Arthrodesis showed position of fusion of 31° (12-70) abduction, 20° (10-50) forward flexion and 22° (- 14 to 58) internal rotation. The unaffected side was significantly (p ≤ 0.05) stronger in every movement direction., Conclusion: At a mean of 20 years after shoulder arthrodesis, patients with an upper brachial plexus lesion are still satisfied with a good to moderate functional improvement., Level of Evidence Iii: A retrospective cohort study.

Purpose: Patient-specific instruments (PSI) were initially developed for the alignment of both total knee- (TKA) and partial knee arthroplasty (PKA). We hypothesize that CT-based PSI for PKA-to-TKA revision surgery can restore biomechanical limb alignment and prosthetic component positioning in vivo as calculated pre-operatively, resulting in a limited percentages of outliers., Methods: An imaging analysis was performed using CT-based 3D measurement methods based on a pre- and post-revision CT scan. Imaging data were gathered on 10 patients who were operated for PKA-to-TKA revision with the use of PSI based on CT imaging. The planned femur and tibia component position in vivo were compared with the pre-revision planned component position. Outliers were defined as deviations >3.0° from pre-revision planned position for the individual implant components. Adjustments (e.g. resection level and implant size) during surgery were recorded., Results: The HKA axis was restored accurately in all patients with a mean post-operative HKA axis of 178.1° (1.4°). Five femoral (2 varus, 2 internal rotation and 1 extension) and 14 tibial guides (2 varus, 6 anterior slope, 3 internal rotation and 3 external rotation) on a total of 60 outcome measures were identified as outliers. During surgery, an intraoperative tibial resection of 2 mm extra was performed in three patients. In 80 and 70% for, respectively, the femur and tibia, the surgeon-planned size was implanted during surgery. All patient-specific guides fitted well in all patients. No intraoperative or post-operative complications related to surgery were registered., Conclusions: This study introduced a unique new concept regarding PSI, PKA-to-TKA revision surgery. Based on the results, we were unable to fully confirm our hypothesis. PSI as a "new" tool for PKA-to-TKA revision surgery appears to be an accurate tool for the alignment of the TKA femur component. The tibial guide seems more susceptible to errors, resulting in a substantial percentage of outliers., Level of Evidence: Prospective cohort study, Level II.

Purpose: The purpose of this study was to evaluate the 5-year follow-up results of the first 200 total knee arthroplasties (TKA) performed by one high-volume surgeon, using patient-specific information (PSI). To date, there has been no other research into the mid-term follow-up of TKA performed using PSI., Materials and Methods: A total of 184 consecutive patients (200 TKA) were evaluated. Outcome measures included implant survival rate, adverse events, and the following patient-reported outcome measures (PROMs); Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Oxford Knee Score (OKS), Pain Visual Analogue Score (VAS) and EuroQol-5D Score (EQ-5D)., Results: Revision surgery was performed for late secondary prosthetic joint infection (n = 1, total revision), aseptic loosening (n = 1, tibial component revision), instability (n = 1, isolated polyethylene insert exchange), and polyethylene insert breakage (n = 1, isolated polyethylene insert exchange). Other adverse events were as follows: debridement, antibiotics and implant retention for early prosthetic joint infection (n = 1), surgical debridement for haemarthrosis (n = 1), superficial wound infection (n = 2), thromboembolic events (n = 2), compartment syndrome (n = 1), and nerve injury (n = 2). All median outcome scores for patient reported outcome measures at 5 years improved significantly compared with the preoperative values (p ≤ 0.05). Median outcome scores were not significantly different between 1- and 5-year moments of follow-up, except for a significant decrease of EQ-VAS (p ≤ 0.05) between these two follow-up moments., Conclusion: PROMs are consistent for 5-year follow-up of TKA using PSI. After 5 years of follow-up, revision surgery for any reason occurred in four patients (2%)., Level of Evidence: III.

Purpose: Patient-specific instrumentation (PSI) is a technique to plan and position the prosthesis components in unicompartmental knee arthroplasty (UKA) surgery. This study assesses whether the definitive component position in the frontal, sagittal and axial plane is according to the preoperative plan, based on the hypothesis that PSI is accurate., Methods: Twenty-six patients who had PSI Oxford UKA surgery were included prospectively. The component position in vivo was determined with a postoperative CT-scan and compared with the planned component position using MRI-based digital 3D imaging. Adjustments to the preoperative plan and implanted component sizes during surgery were recorded., Results: Intraoperatively, no femoral adjustments were performed; 12 tibial re-resections were necessary. The median absolute deviation from the plan in degrees (range) in the frontal, sagittal and axial plane was 1.8° (- 1.5°-6.5°), 2.0° (- 6.5°-8.0°) and 1.0° (- 1.5°-5.0°) for the femoral component, and 2.5° (- 1.0°-6.0°), 3.0° (- 1.0°-5.0°) and 5.0° (- 6.5°-12.5°) for the tibial component. The femoral component is positioned 0.5 (- 1°-2.5°) mm more lateral and 0.8 (- 1.0°-2.5°) mm more anterior. The tibial component is positioned 2.0 (- 5.0-0.0) mm more lateral and 1.3 (- 3.0-6.0) mm more distal. The femoral and tibial default plans were changed four times (15.4%) and nine times (34.6%), respectively, before approval by the surgeon., Conclusion: PSI in Oxford UKA surgery is reliable and accurately translates the preoperative plan into the in vivo situation, except for the tibial rotational position. The preoperative planning is a crucial step in avoiding re-resections that can cause angular deviations in prosthesis position, especially in tibial component rotational position. It is advised to avoid re-resections and to consider this while planning the PSI procedure., Level of Evidence: Prospective comparative study Level II.

Purpose: Postoperative urinary retention (POUR), defined as the inability to empty the bladder voluntary after surgery, is a commonly reported complication. This study reports the incidence and possible risk factors for POUR after elective fast-track hip or knee arthroplasty when using a nurse-led bladder scan protocol., Methods: This retrospective cohort study included data from 803 patients who underwent unilateral hip or knee arthroplasty. Patients' digital clinical records were reviewed for eligibility. Patients with incomplete data registration, preoperative bladder volume >250 ml, preexisting bladder catheterization, and/or patients following the outpatient pathway were excluded. Bladder volumes were assessed at different moments pre- and postoperatively. The outcome was the incidence of POUR, defined as the inability to void spontaneously with a bladder volume >600 ml, treated with indwelling catheterization. Further analysis between POUR and non-POUR patients was performed to detect possible risk factors for POUR., Results: Six hundred and thirty-eight patients operated on primary unilateral hip or knee arthroplasty were analyzed. The incidence of POUR was 12.9% (n = 82, 95% CI 9.4-15.5). Gender, age, BMI, ASA classification, preoperative bladder volume, type of anesthesia, type of arthroplasty, and perioperative fluid administration were not significant different between POUR and non-POUR patients. Patients with a bladder volume of >200 ml at the recovery room were at higher risk (OR 5.049, 95% CI 2.815-9.054) for POUR., Conclusions: When using a nurse-led bladder scan protocol in fast-track hip and knee arthroplasty, the incidence of POUR was 12.9%, with a bladder volume of >200 ml at the recovery room as a risk factor for POUR., Level of Evidence: A retrospective cohort study, Level III.

Purpose: The aim of this multicentre cohort study was to evaluate the midterm outcomes and survival after cementless stemless resurfacing arthroplasty (CSRA) in a series of 33 shoulders in 27 patients with primary osteoarthritis., Methods: Clinical outcome assessment included: Constant-Murley score (CMS); Simple Shoulder Test (SST); Disability of Arm, Shoulder, Hand (DASH); EuroQol-5D (EQ-5D) utility scores; Numerous Rating Scale (NRS) for pain. Radiographs were assessed by two independent observers for oversizing, radiolucency, glenohumeral subluxation, glenoid erosion and subsidence. Correlations between the clinical and radiological outcomes were calculated. Complications were registered, and revision and survival rates were calculated., Results: Mean age at time of surgery and mean follow-up time were, respectively, 67.7 (range 50.2-85.1) and 7.2 years (range 5.7-9.3 years). Means (SD) for CMS, age- and gender-adjusted CMS, SST, DASH and EQ-5D utility scores were: 56.4 (20.2), 76.5 (25.0), 54.0 (29.8), 37.6 (23.3) and 0.8 (0.1), respectively. NRS for pain was 2.0 and 3.8, respectively, in rest and during activities. Radiographic assessment of the CSRAs showed oversizing in 54.5%; radiolucency in 18.2%; superior glenohumeral subluxation in 33.3%; glenoid erosion in 45.5%; and subsidence in 3.0%. Perioperative complications did not occur. Revision surgery was performed in one patient (3.0%)., Conclusion: For primary osteoarthritis, the CSRA showed good clinical but poor radiological outcomes at midterm follow-up.

Purpose: To compare the patients ability to forget the artificial knee joint in everyday life who were randomized to be operated for mobile- or fixed-bearing total knee arthroplasty (TKA)., Methods: This single-center randomized controlled trial evaluated the 3-year follow-up of the cemented mobile- and fixed-bearing TKA from the same brand in a series of 41 patients. Clinical examination was during the pre-, 6-week, 6-month, 1-, 2- and 3-year follow-up containing multiple patient-reported outcome measures (PROMs) including the 12-item Forgotten Joint Score (FJS-12) at 3 years. Effect size was calculated for each PROM at 3-year follow-up to quantify the size of the difference between both bearings., Results: At 3-year follow-up, general linear mixed model analysis showed that there were no significant or clinically relevant differences between the two groups for all outcome measures. Calculated effect sizes were small (<0.3) for all the PROMs except for the FJS-12; these were moderate (0.5)., Conclusion: The results of this study demonstrate that joint awareness was slightly lower in patients operated with the MB TKA with comparable improved clinical outcome and PROMs at 3-year follow-up. Measuring joint awareness with the FJS-12 is useful and provides more stringent information at 3-year follow-up compared to other PROMs and should be the PROM of choice at each follow-up after TKA., Level of Evidence: Level I, randomized controlled trial.

Background: To determine whether computed tomography (CT) or magnetic resonance imaging (MRI) is more suitable for the patient-specific instrumentation (PSI) systems for total knee arthroplasty (TKA)., Methods: PubMed, Embase, and the Cochrane Library were searched from inception to June 2016 for prospective comparative trials that compared CT- versus MRI-based PSI systems for TKA. Our predefined primary outcome was the outliers incidence of coronal overall limb alignment., Results: Six studies with a total of 336 knees meeting the eligibility criteria, and four trials were included in the meta-analysis. Compared with MRI-based PSI systems, CT-based PSI systems were associated with a higher outliers incidence of coronal overall limb alignment (risk ratio: 1.67; 95% confidence interval (CI): 1.03-2.72; P = 0.04), more angular errors of coronal overall limb alignment (mean difference (MD): 1.01°; 95% CI: 0.47-1.56; P = 0.0003), and longer operation time (MD: 5.02 min; 95% CI: 1.26-8.79; P = 0.009). While no significant differences in the coronal/sagittal alignment of the femoral/tibial component outliers, the angular errors of coronal overall limb alignment, the angular errors of the femoral/tibial component in coronal plane, or incidence of change of implant size of the femoral/tibial component were observed., Conclusions: The current limited evidence suggests that MRI-based PSI systems exhibit higher accuracy for TKA regarding the coronal limb axis than CT-based PSI systems. However, well-designed studies comparing CT-versus MRI-based PSI systems for TKA are warrant to confirm these results before widespread use of this technique can be recommended., (Copyright © 2017 Royal College of Surgeons of Edinburgh (Scottish charity number SC005317) and Royal College of Surgeons in Ireland. Published by Elsevier Ltd. All rights reserved.)

Purpose: Patients-specific instruments (PSI) for implantation of total knee arthroplasty (TKA) can be used to predict the implant size for both the femur and the tibia component. This study aims to determine the impact of approval of the PSI planning for TKA on the frequency of, and reason for intraoperative changes of implant sizes., Methods: The clinical records of 293 patients operated with MRI- (90.4 %) and CT-based (9.6 %) PSI were reviewed for actual used implant size. Preoperative default planning from the technician and approved planning by the operating surgeon were compared with the intraoperative implanted component size for both the femur and tibia. Intraoperative reason for not following the default sizes was outdated. Furthermore, MRI- and CT-based PSI were compared for these outcomes., Results: In 93.9 and 91.1 % for, respectively, the femur and tibia (n.s.), the surgeon planned size was implanted during surgery. The predicted size of the femur (p < 0.00) and the tibia (p < 0.00) component planned by a technician differed from the implanted component sizes in 62 (21.2 %) and 51 (17.4 %) patients, respectively. In 17 cases, the femoral component size was adapted intraoperative based on the expert opinion of the operating surgeon. In 26 cases, the tibia component was changed during the surgery because of a mediolateral overhang, sclerotic bone, medial or lateral release, limited extension and/or fixed varus deformity. The results between the MRI- and CT-based PSI did not differ (n.s.)., Conclusions: PSI is a tool to help the surgeon to achieve the best possible results during TKA. The planning made by a technician should always be validated and approved by the operating surgeon who has the ultimate responsibility regarding the operation. With PSI, the operating surgeon is able to minimize intraoperative implant size errors in advance to improve operating room efficiency with possible lowering hospital costs per procedure., Levels of Evidence: III.

Purpose: Previous studies have compared weight-bearing mechanical leg axis (MLA) measurements to non-weight-bearing measurement modalities. Most of these studies compared mean or median values and did not analyse within-person differences between measurements. This study evaluates the within-person agreement of MLA measurements between weight-bearing full-length radiographs (FLR) and non-weight-bearing measurement modalities (computer-assisted surgery (CAS) navigation or MRI)., Materials and Methods: Two independent observers measured the MLA on pre- and postoperative weight-bearing FLR in 168 patients. These measurements were compared to non-weight-bearing measurements obtained by CAS navigation or MRI. Absolute differences in individual subjects were calculated to determine the agreement between measurement modalities. Linear regression was used to evaluate the possibility that other independent variables impact the differences in measurements., Results: A difference was found in preoperative measurements between FLR and CAS navigation (mean of 2.5° with limit of agreement (1.96 SD) of 6.4°), as well as between FLR and MRI measurements (mean of 2.4° with limit of agreement (1.96 SD) of 6.9°). Postoperatively, the mean difference between MLA measured on FLR compared to CAS navigation was 1.5° (limit of agreement (1.96 SD) of 4.6°). Linear regression analysis showed that weight-bearing MLA measurements vary significantly from non-weight-bearing MLA measurements. Differences were more severe in patients with mediolateral instability (p = 0.010), age (p = 0.049) and ≥3° varus or valgus alignment (p = 0.008)., Conclusion: The clinical importance of this study lies in the finding that there are within-person differences between weight-bearing and non-weight-bearing measurement modalities. This has implications for preoperative planning, performing total knee arthroplasty (TKA), and clinical follow-up after TKA surgery using CAS navigation or patient-specific instrumentation., Level of Evidence: III.

Purpose and Hypothesis: The purpose of this study was to 'objectively' measure improvement of physical activity with the use of an activity monitor between patients who followed an enhanced recovery- or outpatient surgery pathway after total knee arthroplasty (TKA). It was hypothesized that both pathways will have comparable physical activity after TKA at 6-week follow-up., Methods: This prospective observational comparative case study was designed to investigate activity parameters (e.g. physical activity, number of steps, sit-stand transfers) of two different pathways after 6 weeks with the use of a non-invasive triaxial accelerometer activity monitor. This study included 20 patients with a mean age of 65.5 years (SD 6.1) undergoing TKA who were allocated to follow one of the two pathways: enhanced recovery (n = 10) or outpatient surgery (n = 10). Patients were monitored for 4 days pre-, 4 days during and 4 days after 5 weeks postoperatively. Patient-reported outcome measures (PROMs) and range of knee motion were obtained pre- and 6 weeks postoperatively., Results: The activity parameters recovered steeply during the first 4 postoperative days and continued to improve within both pathways (n.s.). Preoperative and during the first 4 days and 5 weeks postoperative, activity parameters were comparable (n.s.) between both pathways but did not reach preoperative levels of physical activity and range of motion (n.s.). PROMs improved within each pathway, and no difference between both pathways was observed (n.s.)., Conclusions: This study demonstrates that the early physical activity parameters of patients after TKA, following the outpatient surgery pathway, were similar to patients who followed the standard enhanced recovery pathway. The activity monitor is an added value for a more detailed and objective analysis of the physical performance in patients after TKA., Level of Evidence: III.

Background: Short-segment pedicle-screw instrumentation is frequently used to stabilize thoracolumbar burst fractures. A recognized disadvantage of this procedure is recurrent kyphosis from intervertebral disc creep into the fractured central endplate. Balloon Assisted Endplate Reduction (BAER) using Tricalcium Phosphate bone cement (TCP) enables elevation of the centrally depressed endplate. Our objective was to evaluate the bone-tissue response to TCP and to analyse whether BAER using TCP can prevent recurrent kyphosis after removal of the instrumentation., Methods: Fourteen patients with traumatic thoracolumbar burst fractures were operated with BAER using TCP in combination with short-segment instrumentation. Nine months after surgery, instrumentation was removed and transpedicular biopsies were taken for histological and histochemical analysis. Roentgenograms pre- and postoperatively and at latest follow-up after removal of the instrumentation were evaluated., Results: Average follow-up was 2.6 years. Analysis of the biopsies showed a variable degree of bone remodelling with incorporation of TCP into newly formed bone matrix. No extensive foreign body reactions, inflammation, granulomatous responses or tissue necrosis were observed. Wedge-angle, kyphosis-angle and both the anterior-posterior and central-posterior vertebral body height ratios improved significant postoperatively (p < 0.001). After removal of the instrumentation no significant differences in wedge-angle or height ratios were seen (p = 0.12). The kyphosis-angle increased four degrees (p = 0.01)., Conclusion: TCP showed good histological osseointegration with no adverse events. TCP can therefore be safely used and could be beneficial in treatment of thoracolumbar burst fractures. BAER with TCP in combination with short-segment instrumentation might reduce recurrence of deformity even after removal of the instrumentation in comparison to short-segment instrumentation alone., Trial Registration: This study is registered at the at the Dutch Trial Registry (NTR3498).

Purpose: There has been increasing interest in accelerated programs for knee arthroplasty. We examined the efficacy and safety of an outpatient surgery (OS) pathway in patients undergoing unicompartmental knee arthroplasty (UKA)., Methods: This case-controlled study evaluates patients operated for UKA in an OS pathway (n = 20) compared to rapid recovery (RR), the current standard (n = 20). We investigated whether patients could be discharged on the day of surgery, resulting in comparable or better outcome by means of adverse events (AEs) in terms of pain (numerical rating scale, NRS), incidences of postoperative nausea and vomiting (PONV) and opiate use (<48 h postoperatively), complication and readmission rates (<3 months postoperatively). Patient-reported outcome measures (PROMS) were obtained preoperatively and 3 months postoperatively., Results: Postoperative pain (NRS > 5) was the most common reason for prolonged hospital stay in the OS pathway. Eighty-five per cent of the patients were discharged on the day of surgery, whereas 95 % of the patients were discharged on postoperative day 3 in the RR pathway. Overall, median pain scores in both pathways did not exceed a NRS score of 5, without significant differences (RR vs. OS) in the number of patients with PONV (4 vs. 2) and opiate use (11 vs. 9) <48 h postoperatively. At 3 months postoperatively, no significant differences were found for AEs and PROMS between both pathways., Conclusion: The results of this study illustrates that an OS pathway for UKA is effective and safe with acceptable clinical outcome. Well-established and adequate standardized protocols, inclusion and exclusion criteria and a change in mindset for both the patient and the multidisciplinary team are the key factors for the implementation of an OS pathway., Level of Evidence: Case-control study, Level III.

Purpose: A concern that arises with any new prosthesis is whether it will achieve satisfactory long-term implant stability. The gold standard of assessing the quality of fixation in a new or relatively new implant is to undertake a randomized controlled trial using radiostereometric analysis. It was hypothesized that both mobile-bearing total knee arthroplasty and fixed-bearing total knee arthroplasty have comparable migration patterns at 2-year follow-up. This study investigated two types of cemented total knee arthroplasty, the mobile- or fixed-bearing variant from the same family with use of radiostereometric analysis., Methods: This prospective, patient-blinded, randomized, controlled trial was designed to investigate early migration of the tibia component after two years of follow-up with use of radiostereometric analysis. A total of 50 patients were randomized to receive a mobile- or fixed-bearing TKA from the same family. Patients were evaluated during 2-year follow-up, including radiostereometric analysis, physical and clinical examination and patient reported outcome measures (PROMs)., Results: At two-year follow-up, the mean (±SD) maximum total point motion (MTPM) in the fixed-bearing group was 0.82 (±1.16) versus 0.92 mm (±0.64) in the mobile-bearing group (p = n.s) with the largest migration seen during the first 6 weeks (0.45 ± 0.32 vs. 0.54 ± 0.30). The clinical outcome and PROMs significantly improved within each group, not between both groups., Conclusions: Measuring early micromotion is useful for predicting clinical loosening that can lead to revision. The results of this study demonstrate that early migration of the mobile-bearing is similar to that of the fixed-bearing component at two years and was mainly seen in the first weeks after implantation., Level of Evidence: Randomized, single-blind, controlled trial, Level I.

Background: Hypothermia is an important complication in joint arthroplasty. Commonly, forced air warming (FAW) devices are used intraoperatively to maintain body temperature in patients undergoing surgery. However, it is believed that these convective warming systems could increase the risk of deep surgical site infections due to disruption of unidirectional downward laminar airflow. Conductive warming devices have no noticeable effect on ventilation airflow. Nevertheless, the effectiveness of the self-warming (SW) blanket, a novel conductive warming device, on postoperative hypothermia in elective joint arthroplasty is unknown., Purpose: The purpose of this study was to evaluate the effectiveness of early warming with SW blankets in the prevention of postoperative hypothermia in elective total hip (THA) and knee arthroplasty (TKA) compared with FAW devices., Methods: Patients who underwent elective THA or TKA between May and June 2014 were assigned in the FAW or SW group. A total of 105 patients were enrolled into the study. In the FAW group, the FAW devices were applied after disinfection of the surgical site. In the SW group, the SW blankets were already applied in the orthopaedic department. The duration of warming with SW blankets before anesthetic induction was documented. The body temperature was measured preoperatively upon arrival in the orthopaedic department and postoperatively upon arrival in the postanesthesia care unit. The patient's body temperature was measured at the tympanic membrane, and hypothermia was defined as a body temperature of less than 35.5°C., Results: The SW blankets were applied for a median of 86.8 minutes (78.8-94.8) before anesthetic induction. Postoperative hypothermia was observed in 15 (31.3%) and eight (14.0%) patients in the FAW group and the SW group, respectively (p = .029). The median postoperative body temperature was 35.59°C (35.44-35.74) and 35.95°C (35.83-36.06) in the FAW group and the SW group, respectively (p < .001)., Conclusion: Early warming with SW blankets was more effective than FAW devices in the prevention of postoperative hypothermia in elective THA and TKA.

Background: In this case report, we describe a left-arm both-bone forearm fracture in a 15-year-old girl who fell off a swing. Conservative treatment with an above-elbow cast failed, resulting in a malunion with functional impairment. The pro- and supination were 90/0/10, respectively. The patient complained of difficulties performing daily activities. For this pediatric case, a corrective osteotomy was proposed using a CT-guided technique aiming for maximum anatomical and functional outcome. It was the first time this technique was used in our hospital., Methods: A corrective osteotomy of the patient's left arm was performed using 3D printed templates to guide the osteotomy orientation. These templates were produced using specialized software in which CT images of her malunited left forearm were overlaid with the mirrored images of her healthy right forearm., Results: The postoperative CT-scan showed a near-anatomical reduction with close to 1° correction in all three planes, as compared to the preoperative planning. Three months after surgery, the patient had regained full function of her left forearm., Conclusion: Although this was the first time this technique was used in our hospital, it resulted in excellent anatomical and functional outcomes making it a safe, reliable and precise treatment option that may be useful for even more complex corrections., Level of Evidence: Level V., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Purpose: To assess whether there is a significant difference between the alignment of the individual femoral and tibial components (in the frontal, sagittal and horizontal planes) as calculated pre-operatively (digital plan) and the actually achieved alignment in vivo obtained with the use of patient-specific positioning guides (PSPGs) for TKA. It was hypothesised that there would be no difference between post-op implant position and pre-op digital plan., Methods: Twenty-six patients were included in this non-inferiority trial. Software permitted matching of the pre-operative MRI scan (and therefore calculated prosthesis position) to a pre-operative CT scan and then to a post-operative full-leg CT scan to determine deviations from pre-op planning in all three anatomical planes., Results: For the femoral component, mean absolute deviations from planning were 1.8° (SD 1.3), 2.5° (SD 1.6) and 1.6° (SD 1.4) in the frontal, sagittal and transverse planes, respectively. For the tibial component, mean absolute deviations from planning were 1.7° (SD 1.2), 1.7° (SD 1.5) and 3.2° (SD 3.6) in the frontal, sagittal and transverse planes, respectively. Absolute mean deviation from planned mechanical axis was 1.9°. The a priori specified null hypothesis for equivalence testing: the difference from planning is >3 or <-3 was rejected for all comparisons except for the tibial transverse plane., Conclusion: PSPG was able to adequately reproduce the pre-op plan in all planes, except for the tibial rotation in the transverse plane. Possible explanations for outliers are discussed and highlight the importance for adequate training surgeons before they start using PSPG in their day-by-day practise., Level of Evidence: Prospective cohort study, Level II.

Purpose: General consensus of patient selection criteria for outpatient joint arthroplasty is lacking, which is paramount to prevent prolonged hospital stay, adverse events and/or readmissions. This review highlights patient selection criteria for OJA based on the current literature and expert opinion., Methods: A search of the English and International electronic healthcare databases including MEDLINE/PubMed, EMBASE, AMED and the Cochrane library was performed in November 2015 to include studies published during the last 10 years. Furthermore, a survey of physicians from different specialties was performed., Results: Fourteen studies described results regarding outpatient joint arthroplasty. Studies on outpatient hip and/or knee arthroplasty resulted in similar outcome in preselected patients. Patients who are able and willing to participate, with a low ASA classification (II), bleeding disorders, poorly controlled and/or severe cardiac (e.g. heart failure, arrhythmia) or pulmonary (e.g. embolism, respiratory failure) comorbidities, uncontrolled DM (type I or II), a high BMI (>30 m 2 /kg), chronic opioid consumption, functional neurological impairments, dependent functional status, chronic/end-stage renal disease and/or reduced preoperative cognitive capacity should be excluded from outpatient joint arthroplasty. The expert opinion-based selection criteria were comparable to literature with a further extension of exclusion for patients with practical issue's, urologic medical history and/or severe mobility disorders., Conclusion: Based on the current literature, the presented patient selection criteria provide a basis for outpatient joint arthroplasty and can be useful when selecting patients. Together with a change in mindset, a multidisciplinary approach and literature-based protocols, outpatient joint arthroplasty can be applied in daily orthopaedic practice while ensuring patients' safety., Level of Evidence: Clinical review, Level III.

Purpose: Local infiltration analgesia (LIA) is widely applied in patients undergoing total knee arthroplasty (TKA). In daily practice, adrenaline is added to the LIA mixture to achieve vasoconstriction. However, adrenaline has some possible negative side effects (e.g. tissue necrosis). This trial investigated whether ropivacaine alone is at least as effective for postoperative pain relief after LIA., Methods: Fifty patients scheduled for primary TKA were included in this prospective randomized, double-blind, controlled pilot study receiving high-volume (150 mL) single-shot intra-capsular LIA with ropivacaine (2 %) with (Ropi+) or without (Ropi-) adrenaline (0.01 %). All patients received the same pre-, peri- and postoperative care with multimodal oral pain protocol. Postoperative pain was assessed before and after the first mobilization and during the first 48 h postoperative using the visual analogue scale (VAS). Secondary outcomes were rescue medication use, early mobilization, length of hospital stay, adverse events (AE's) and readmission rates. Patient reported outcomes measures (PROMS); Oxford Knee Score and WOMAC, were obtained preoperative and 3 months postoperative., Results: VAS scores were not significantly different before (n.s.) and after the first mobilization (n.s.), neither over the first 48 h postoperative (n.s.). Patients who needed rescue medication (n.s.), who mobilized <6 h postoperative (n.s.), who were discharged before postoperative day 3 (n.s.), AE's and readmission rate (n.s.) were comparable between both groups. At 3-month follow-up, PROMS significantly improved within both groups., Conclusion: To prevent possible negative side effects (e.g. tissue necrosis), adrenaline should be omitted from the LIA mixture. Single-shot LIA with ropivacaine alone results in clinical acceptable adequate pain control and can be used in daily TKA practice., Level of Evidence: Randomized, double-blind, prospective clinical trial, Level I.

Purpose: Although fewer tibial radiolucent lines are observed in cementless Oxford unicompartmental knee arthroplasty (UKA) compared with cemented Oxford UKA, an independent comparative study on this topic is lacking., Methods: In this multicentre retrospective study, a cohort of 60 consecutive cases of cementless Oxford UKA is compared with a cohort of 60 consecutive cases of cemented Oxford UKA. Radiolucent lines, survival, perioperative data and clinical results were compared., Results: No complete tibial radiolucent lines were observed in either group. Seventeen per cent of partial tibial radiolucent lines were observed in the cementless group versus 21 % in the cemented group (n.s.). The percentage of tibial radiolucent zones was 4 versus 9 %, respectively (p = 0.036). Survival rates were 90 % at 34 months for the cementless group and 84 % at 54 months for the cemented group (n.s.). Mean operation time was 10 min shorter in the cementless group (p < 0.001), and clinical results were not significantly different., Conclusions: Although no significant differences in radiolucent lines were found between both groups, they appear to be more common in the cemented group. This confirms previous results from reports by prosthesis designers. The presence of radiolucent lines after cemented Oxford UKA does not correlate with clinical outcome or survival., Level of Evidence: III.

Purpose: Implant position is an important factor in unicompartmental knee arthroplasty (UKA) surgery. Results on conventional UKA alignment are commonly described in literature. Patient-specific guiding (PSG) is a new technique for positioning the Oxford UKA. Our hypothesis is that PSG improves component position without affecting the HKA angle., Methods: This prospective study compares the results of our first thirty cases of cementless Oxford UKA using PSG with thirty cases using conventional outlining. Baseline characteristics for both groups were identical. Details on handling of the guide, estimated blood loss and operation time were recorded. Postoperative screened radiographs and standing long-leg radiographs of both groups were compared., Results: Median AP position of the femoral component was 3 degrees varus (-5 to 9) using PSG versus 2 degrees varus (-10 to 8) for the conventional group. For the femoral flexion, this was 9 degrees flexion (0-16) using PSG versus 12 degrees flexion (0-20). The tibial median AP position was 1 degree varus (-3 to 7) using PSG versus 2 degrees varus (-5 to 10). The median tibial posterior slope was 5 degrees (1-10) using PSG versus 5 degrees (0-12). All guides aligned well. No conversion to conventional outlining was performed, and no significant changes had to be made to the original approved plan. Operation time, estimated blood loss and postoperative haemoglobin drop were not significantly different between both groups., Discussion: Implant position was not different between both groups, even in the early phase of the learning curve. Perioperative results were not different between both groups., Level of Evidence: III.