Aims. We aimed to assess the reliability and validity of OpenPose, a posture estimation algorithm, for measurement of knee range of motion after total knee arthroplasty (TKA), in comparison to radiography and goniometry. Methods. In this prospective observational study, we analyzed 35 primary TKAs (24 patients) for knee osteoarthritis. We measured the knee angles in flexion and extension using OpenPose, radiography, and goniometry. We assessed the test-retest reliability of each method using intraclass correlation coefficient (1,1). We evaluated the ability to estimate other measurement values from the OpenPose value using linear regression analysis. We used intraclass correlation coefficients (2,1) and Bland–Altman analyses to evaluate the agreement and error between radiography and the other measurements. Results. OpenPose had excellent test-retest reliability (intraclass correlation coefficient (1,1) = 1.000). The R. 2. of all regression models indicated large correlations (0.747 to 0.927). In the flexion position, the intraclass correlation coefficients (2,1) of OpenPose indicated excellent agreement (0.953) with radiography. In the extension position, the intraclass correlation coefficients (2,1) indicated good agreement of OpenPose and radiography (0.815) and moderate agreement of goniometry with radiography (0.593). OpenPose had no systematic error in the flexion position, and a 2.3° fixed error in the extension position, compared to radiography. Conclusion. OpenPose is a reliable and valid tool for measuring flexion and extension positions after TKA. It has better accuracy than goniometry, especially in the extension position. Accurate measurement values can be obtained with low error, high reproducibility, and no contact, independent of the examiner’s skills. Cite this article: Bone Joint Res 2023;12(5):313–320

Aims

To assess the incidence of radiological lateral osteoarthritis (OA) at 15 years after medial unicompartmental knee arthroplasty (UKA) and assess the relationship of lateral OA with symptoms and patient characteristics.

The shape of the flexion gap in 20 normal knees was evaluated by axial radiography of the distal femur, and the results compared with those obtained in a previous study by MRI. The observed asymmetry was reduced by 29% using radiography, with a mean value of 3.6° (1.5° to 6.3°) compared with that obtained by MRI of 5.1° (2.6° to 9.5°), a mean discrepancy of 1.49°. The results obtained by radiography and MRI showed a strong correlation (r = 0.78). Axial radiography is acceptable for the evaluation of the flexion gap and is less expensive and more comfortable to perform than MRI. Additionally, no metallic artefact occurs when the radiological method is used for assessment after arthroplasty

We have previously developed a radiographic technique, the oblique posterior condylar view, for assessment of the posterior aspect of the femoral condyles after total knee arthroplasty. The purpose of this study was to confirm the validity of this radiographic view based upon intra-operative findings at revision total knee arthroplasty. Lateral and oblique posterior condylar views were performed for 11 knees prior to revision total knee arthroplasty, and radiolucent lines or osteolysis of the posterior aspect of the femoral condyles were identified. These findings were compared with the intra-operative appearance of the posterior aspects of the femoral condyles. Statistical analysis showed that sensitivity and efficacy were significantly better for the oblique posterior condylar than the lateral view. This method can, therefore, be considered as suitable for routine follow-up radiographs of the femoral component and in the pre-operative planning of revision surgery

Axial radiographs were obtained under valgus and external rotation stress at 45° of knee flexion with and without contraction of the quadriceps muscle in order to assess the dynamics of patellar subluxation or dislocation. The radiography was performed on 82 knees in 61 patients with patellofemoral instability, and on 44 normal knees. The lateral patellofemoral angle and the congruence angle were measured and compared with the conventional Merchant views. Both parameters showed greater differences between symptomatic and normal knees on the stress radiographs obtained without quadriceps contraction. There was a major difference in the lateral patellofemoral angles between the groups, which clearly distinguished symptomatic knees from normal controls. Congruence angles on stress radiography had a significant correlation with the functional scores obtained after a period of conservative treatment and a positive correlation with the frequency of patellar subluxation. When the quadriceps contracted, two patterns of patellar shift were observed. While the patella reduced into the trochlear groove in all normal knees and about 70% of the symptomatic knees, contraction of the quadriceps caused further subluxation of the patella in the remaining symptomatic knees. All the knee joints which showed this displacement failed to respond to conservative treatment and eventually required surgical treatment. Thus, this technique of stress radiography is a simple, cost-effective and useful method of evaluating patellar instability and predicting the prognosis

Abstract

The outcome following arthroscopic anterior cruciate (ACL) reconstruction is dependant on a combination of surgical and non-surgical factors. Technical error is the commonest cause for graft failure, with poor tunnel placement accounting for over 80% of those errors. A routine audit of femoral and tibial tunnel positions following single bundle hamstring arthroscopic ACL reconstruction identified apparent inconsistent positioning of the tibial tunnel in the sagittal plane. Intra-operative fluoroscopy was therefore introduced (when available) to verify tibial guide wire position prior to tunnel reaming. This paper reports a comparison of tibial interference screw position measured on post-operative radiographs with known tunnel position as shown on intra-operative fluoroscopic images in 20 patients undergoing routine primary ACL reconstruction between January and June 2009. Surgery took a mean of 5 minutes longer when intra-operative fluoroscopy was used. In 3/20 patients, fluoroscopy led to re-positioning of the tibial guide wire prior to tunnel reaming. The mean tibial tunnel position as indicated by the tunnel reamer was 41 +/− 2.7 % of the total plateau depth (range 37% to 47%). The mean position projected from the tibial screw on post operative radiographs was 46 +/− 9.2% (range 38% to 76%). A paired t-test showed a significant difference (p = 0.022) between true tunnel position and tibial screw position. 6/20 patients had post operative screw positions that were > 5% more posterior than the known position of the tibial tunnel. The position of the tunnel should be measured at its mid-point where this is evident. On most early radiographic images, the margins of the tunnel are not clear and therefore a line projected from the centre of the screw is used. This audit demonstrates the potential inaccuracy associated with this

We took posteroanterior weight-bearing radiographs, both with the joint fully extended and in 30° of flexion, in a consecutive series of 50 knees in 37 patients referred for the primary assessment of pain and/or stiffness. These radiographs were reported ‘blind’ both by an orthopaedic surgeon and a radiologist. Direct measurement of the joint space, together with grading of the severity of erosion according to the Ahlback criteria, was undertaken. Any other abnormality present was also documented.

The radiographs of the knees in 30° of flexion consistently showed more advanced erosion in both the medial (p = 0.001) and the lateral (p = 0.0001) tibiofemoral compartments, when compared with those of knees in full extension. The Ahlback classification of 25 joints was altered, in some cases by several grades, by the flexed position of the joint. In every case in which another abnormality was identified on the radiograph in full extension, it was also noted on that of the knee in 30° of flexion. In a further four cases, additional pathology could only be seen in the flexed knee. Every patient was able to complete the radiological examination without difficulty. Our study supports the adoption of a weight-bearing view in 30° of flexion as the standard posteroanterior radiograph for the assessment of tibiofemoral osteoarthritis in patients over 50 years of age.

Involvement of Patellofemoral joint (PFJ) has significant bearing in the management of osteoarthritis of the knee. The aim of this study is to assess the relationship between skyline radiographs, MRI and arthroscopic findings in the patellofemoral joint.

Data was collected prospectively from fifty-three patients who underwent arthroscopy. There were 36 males and 17 females in the group with mean age of 48 years (range 18-71). Arthroscopically PFJ arthritis was classified based on Outerbridge grading system. Patients with Outerbridge grade III and IV lesions were considered to have significant arthritis of the PFJ. Kellgren-Lawrence grading system was used to assess the skyline radiographs. Radiographically patients with grade III and IV Kelgren-Lawrence changes were considered to have significant osteoarthritis of the PFJ. MRI scans were also studied to assess involvement of PFJ. Thirty-two patients had MRI scan and 20 patients had skyline views done as part of preoperative work up. Arthroscopic findings were considered as gold standard.

MRI scan had specificity of 75%, sensitivity of 81%, positive predictive value of (PPV) 77 and negative predictive value of (NPV) 80% in diagnosing significant PFJ arthritis. Skyline radiographs had specificity of 100%, sensitivity of 50%, PPV of 100% and NPV of 57%. The overall accuracy of skyline radiographs in predicting significant PFJ arthritis was 70% and for MRI was 78%. We conclude that skyline radiographs has some value in he diagnosis of PFJ arthritis, however the sensitivity and negative predictive value is very is poor.

Introduction

This study investigates and compares the accuracy of pre-operative templating from the AP and lateral radiographs in total knee arthroplasty.

Abstract. Introduction. Anecdotal reports suggest some cementless Oxford Unicompartmental Knee Replacements (OUKRs) have painful early subsidence of the tibial component with valgus rotation and/or posterior tilting. The incidence of subsidence and its association with pain is poorly understood. This radiographic study aimed to evaluate the incidence of tibial subsidence and five-year patient reported outcome measures (PROMs) of a cementless OUKR cohort. Methodology. Cementless OUKRs from a high-volume centre with acceptable post-operative and five-year radiographs were included. Subsidence was determined by measuring the angle of the tibial tray/tibial axis angle and distance between the tibial tray axis and fibula head on anteroposterior and lateral radiographs using a custom MATLAB program. Analysis of 5-year PROMs assessed the relationship between subsidence and pain. Radiographs indicating tibial subsidence were validated by two observers. Results. Radiographs of 94 cementless OUKRs were analysed of which five tibial components had subsided (incidence=5%) with an average of 1.92° varus rotation and 2.97° posterior tilt. Subsidence appeared to occur within the first post-operative year with all tibial components fixed securely at 5 years. Two subsiders had moderate pain (ICOAP=20.5,15.9, AKSS Pain=20,45) and lower Oxford Knee Scores (OKS=26,31) compared to the cohort means (ICOAP=3.91, AKSS Pain=45.9, OKS = 43.6). These two subsiders had BMIs greater than 30. Conclusion. This study found 5% of cementless OUKRs in the cohort underwent tibial subsidence. Subsidence with moderate pain occurred in 2% of cases, and pain may be associated with obesity. A larger study is needed to study subsidence in greater detail

Aims. Periprosthetic joint infection (PJI) is a challenging complication of any arthroplasty procedure. We reviewed our use of static antibiotic-loaded cement spacers (ABLCSs) for staged management of PJI where segmental bone loss, ligamentous instability, or soft-tissue defects necessitate a static construct. We reviewed factors contributing to their failure and techniques to avoid these complications when using ABLCSs in this context. Methods. A retrospective analysis was conducted of 94 patients undergoing first-stage revision of an infected knee prosthesis between September 2007 and January 2020 at a single institution. Radiographs and clinical records were used to assess and classify the incidence and causes of static spacer failure. Of the 94 cases, there were 19 primary total knee arthroplasties (TKAs), ten revision TKAs (varus-valgus constraint), 20 hinged TKAs, one arthrodesis (nail), one failed spacer (performed elsewhere), 21 distal femoral endoprosthetic arthroplasties, and 22 proximal tibial arthroplasties. Results. A total of 35/94 patients (37.2%) had spacer-related complications, of which 26/35 complications (74.3%) were because of mechanical failure of the spacer construct, while 9/35 (25.7%) were due to recurrence of infection. Risk factors for internal failure were a construct where the total intramedullary spacer length was less than twice the length of the central osseous defect (p = 0.009), where proximal or distal intraosseous spacer contact was < 10%, and after tibial tubercle osteotomy (p = 0.005). The incidence of spacer complications significantly increased the time to second stage: mean 157 days (42 to 458) in those without complications versus 227 days (11 to 528) with complications (p = 0.014). Conclusion. The failure rate of static antibiotic-loaded cement spacers is much higher than anticipated. Complications of the spacer significantly increased the time to second-stage revision. The risk of mechanical failure is significantly increased if the spacer is less than double the size of the segmental defect, or if inadequate reinforcement is inserted into the residual bone. These findings serve as a guide for surgeons to avoid mechanical complications with static spacers. Cite this article: Bone Joint J 2024;106-B(10):1067–1073

Abstract. Introduction. Changes in posterior tibial slope (PTS) and patellar height (PH) following proximal tibial osteotomies have been a recent focus for knee surgeons. Increased PTS and decreased PH following medial opening wedge high tibial osteotomy (MOWHTO) have been repeatedly reported in the literature. However, this has been disputed in more recent biomechanical studies. Methodology. A total of 62 cases who underwent MOWHTO were included. Surgery was performed using a dedicated step-by-step protocol focusing on the risks of unintentional slope changes. Clinically, all patients were evaluated preoperatively and at 2 years follow-up with the KOOS scores and UCLA physical activity scale. Preoperative and postoperative radiographic lower limb alignment parameters were measured on full-length lower limb radiographs, including (HKA), (MPTA), (mLDFA), proximal posterior tibial angle (PPTA), (JLCA) and(JLO). PH measurements were assessed on radiographs. Results. There was a significant change in the coronal plane alignment; the mMPTA changed from 84.38° to 90.39°, and the HKA changed from 172.19° to 180.15° (Both P < 0.0001). There was no significant change in the PTS as evidenced by a postoperative PPTA of 80.56 ° from a preoperative of 80.36°. And no significant change in the PH with all the indices; preoperative Caton Deschamps, Insall Salvati, and Schröter indices measured 0.95, 1.03, and 1.56, respectively. In comparison to postoperative measures of 0.93, 1.03, and 1.54, respectively. Conclusion. MOWHTO does not change the PTS or PH when accurate preoperative planning and precise intraoperative freehand technique are adopted. Involuntary modification of these anatomic parameters should be considered surgical errors

Abstract. Introduction. Patient selection is key to the success of medial unicondylar knee arthroplasty (UKA). Progression of arthritis is the most common indication for revision. Various methods of assessing the lateral compartment have been used including stress radiography, radioisotope bone scanning, MRI, and visualisation at the time of surgery. Arthroscopy is another means of assessing the integrity of the lateral compartment. Methods. We used per-operative arthroscopy as a means to confirm suitability for UKA in a consecutive series of 279 Oxford medial UKA. This study reports the long-term results of a previously published cohort of knees. Our series of UKA with per-operative arthroscopy (Group 1) was compared to all Oxford UKA (Group 2) and all UKA in the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) (Group 3). Results. The 14-year cumulative percentage revision (CPR) was 18.5% (95% CI 12.7, 26.4) for group 1, 19.7% (95% CI 18.8, 20.6) for group 2, and 19.2% (95% CI 18.5, 19.8) for group 3. There was no statistically significant difference in the (CPR) for the entire period when group 1 was compared to groups 2 or 3. Progression of arthritis was the indication for revision in similar proportions for the three groups (Group 1: 32.3%, Group 2: 35.7% and Group 3: 33.5%). Following per-operative arthroscopy 21.6% (77/356) of knees underwent a change of surgical plan from UKA to TKA. Conclusion. Per-operative arthroscopy may improve medium-term medial unicompartmental knee survivorship but does not improve long-term survivorship nor reduce revision due to progression of arthritis

Abstract. Introduction. Total knee replacement (TKR) in patients with skeletal dysplasia is technically challenging surgery due to deformity, joint contracture, and associated co-morbidities. The aim of this study is to follow up patients with skeletal dysplasia following a TKR. Methodology. We retrospectively reviewed 22 patients with skeletal dysplasia who underwent 31 TKRs at our institution between 2006 and 2022. Clinical notes, operative records and radiographic data were reviewed. Results. Achondroplasia was the most common skeletal dysplasia (8), followed by Chondrodysplasia punctata (7) and Spondyloepiphyseal dysplasia (5). There were fourteen men and eight women with mean age of 51 years (28 to 73). The average height of patients was 1.4 metres (1.16–1.75) and the mean weight was 64.8 Kg (34.3–100). The mean follow up duration was 68.32 months (1–161). Three patients died during follow up. Custom implants were required in twelve patients (38.71%). Custom jigs were utilised in six patients and two patients underwent robotic assisted surgery. Hinged TKR was used in seventeen patients (54.84%), posterior stabilised TKR in nine patients (29.03%), and cruciate retaining TKR in five patients (16.13%). One patient underwent a patella resurfacing for persistent anterior knee pain and another had an intra-operative medial tibial plateau fracture which was managed with fixation. No revisions occurred during the follow up period. Conclusion. Despite the technical challenges and complexity of TKR within this unique patient group, we demonstrate good implant survivorship during the study period. Cross sectional imaging is recommended preoperatively for precise planning and templating

Abstract. Introduction. Fractures of the articular surface of the patella or the lateral femoral condyle usually occur following acute dislocation of the patella. This study looked at the radiological and functional outcomes of fixation of osteochondral fractures. Methods. Twenty-nine patients (18 male, 11 female) sustained osteochondral fractures of the knee following patellar dislocation. All patients had detailed radiographic imaging and MRI scan of the knee preoperatively. An arthroscopic assessment was done, followed by fixation using bio-absorbable pins or headless screws either arthroscopically or mini-open arthrotomy. VMO plication or MPFL repair were done if necessary. MRI scan was done at follow-up to assess for healing of the fixed fragment prior to patient discharge. Results. The mean age of the patients was 21 yrs (9–74), 11 had osteochondral fracture of the patella (38%), while 18 were from the lateral femoral condyle (62%). 13 patients needed additional VMO plication. Mean follow up period was 7.7 years (1 to 12 years). As per Tegner activity scale, all patients returned to their pre-injury activity level (Mean score 7) and sports. None of the patients had a further episode of patellar dislocation. Mean postoperative IKDC score was 86.5 (SD 17.3), Kujala was 91.1(SD 15.5) and Tegner- lysholm was 88.7 (SD 14.4). All patients had statistically significant (p < 0.05) improvement. Post-operative MRI scan showed satisfactory union in all cases (100%). Conclusion. It is extremely important to identify this group of injury and treat them early to have satisfactory knee function and avoid long term complications of arthritis

Abstract. The radiographic or bony landmark techniques are the two most common methods to determine Medial patellofemoral ligament (MPFL) femoral tunnel placement. Their intra/inter-observer reliability is widely debated. The palpation technique relies on identifying the medial epicondyle (ME) and adductor Tubercle (AT). The central longitudinal artery and associated vessels (CLV) are consistently seen in the surgical dissection during MPFL reconstruction. The aim of this study was to investigate the anatomic relationship of CLV to ME-AT and thereby use CLV as an important vascular landmark during MPFL reconstruction. A retrospective review of MRI scans in skeletally mature patients presenting to a tertiary referral knee clinic was undertaken. Group-N consisted of any presentation without patellofemoral instability or malalignment (PFI). Group-P with PFI. MRI's were reviewed and measured by two Consultant Radiologists for the CLV-ME-AT anatomy and relationship. Following exclusions 50 patients were identified in each group. The CLV passed anterior to the AT and ME in all patients. ME morphology did not differ greatly between the groups except in the tubercle height, where there was a statically but not clinically significant difference (larger in the non-PFI group, 2.95mm vs 2.52mm, p=0.002). The CLV to ME Tip distance was consistent between the groups (Group PFI group 3.8mm & ‘normal’ non-PFI Group 3.9mm). The CLV-ME-AT relationship remained consistent despite patients presenting pathology. The CLV consistently courses anterior to ME and AT. The CLV could be used as a vascular landmark assisting femoral tunnel placement during MPFL reconstruction

Introduction. The purpose of this study was to compare the radiographic outcomes of manual versus robotic-assisted medial unicompartmental knee arthroplasty (UKA). Materials & Methods. Postoperative radiographic outcomes from 86 consecutive robotic-assisted UKAs (RAUKA group) from a single academic center were retrospectively reviewed and compared to 253 manual UKAs (MUKA group) drawn from a prior study at our institution. Femoral coronal and sagittal angles (FCA, FSA), tibial coronal and sagittal angles (TCA, TSA), and implant overhang were radiographically measured to identify outliers. Clinical results at 4–6 weeks postoperative were compared to a control cohort of total knee arthroplasty (TKA) patients from our institution. Results. When assessing the accuracy of RAUKAs, 91.6% of all alignment measurements and 99.2% of all overhang measurements were within the target range. All alignment and overhang targets were simultaneously met in 68.6% of RAUKAs. When comparing radiographic outcomes between the RAUKA and MUKA groups, statistically significant differences were identified for combined outliers in FCA (2.3% vs. 12.6%, p=0.006), FSA (17.4% vs. 50.2%, p<0.001), TCA (5.8% vs. 41.5%, p<0.001), and TSA (8.1% vs. 18.6%, p=0.023), as well as anterior (0.0% vs. 4.7%, p=0.042), posterior (1.2% vs. 13.4%, p=0.001), and medial (1.2% vs. 14.2%, p<0.001) overhang outliers. RAUKA demonstrated statistically significant improvements in pain and outcomes compared to TKA at 4–6 weeks (p<0.05). Conclusions. Robotic navigation decreases alignment and overhang outliers compared to manual UKA and improves clinical results compare to TKA in the early postoperative period. Given the association between component placement errors and revision in UKA, this strong significant improvement in accuracy is likely to improve implant survival

Background. Secondary osteonecrosis of the knee (SOK) generally occurs in relatively young patients in their working years; at advanced stages of SOK, the only viable surgical option is total knee arthroplasty (TKA). We conducted a retrospective study to investigate implant survivorship, clinical and radiographic outcomes, and complications of cemented TKA with/without patellar resurfacing for SOK. Methods. Thirty-eight cemented TKAs in 27 patients with non-traumatic SOK with a mean age 43 years (range 17–65) were retrospectively reviewed. Twenty-one patients (78%) were female. Mean body mass index was 31 kg/m. 2. (range 20–48); 11 patients (41%) received bilateral TKAs. Twenty patients (74%) had a history of corticosteroid use and 18% had a history of alcohol abuse. Patellar osteonecrosis was coincidentally found in six knees (16%), all of which had no anterior knee pain and had no patellofemoral joint collapse. The mean follow-up was 7 years (range 2–12). Knee Society Score (KSS) and radiographic outcomes were evaluated at 6 weeks, 1 year, then every 2–3 years thereafter. Results. Ninety-two percent had implant survivorship free from revision with significant improvement in KSS. Causes of revision included aseptic tibial loosening (one), deep infection (one), and instability with patellofemoral issues (one). Four of six cases also with patellar osteonecrosis received resurfacing, including one with a periprosthetic patellar fracture after minor trauma, with satisfactory clinical results after conservative treatment. None of the unrevised knees had progressive radiolucent lines or evidence of loosening. Non-resurfacing of the patella, use of a stem extension or a varus-valgus constrained prosthesis constituted 18%, 8% and 3% of knees, respectively. Conclusion. Cemented TKAs with selective stem extension in patients with SOK had satisfactory implant survivorship and reliable outcomes at a mean of 7 years. Patellar resurfacing is unnecessary in younger patients with no symptoms of anterior knee pain and no patellar collapse radiographically. For any figures or tables, please contact the authors directly

Introduction. Up to 15 % of patients report anterior knee pain (AKP) after a total knee arthroplasty (TKA). The correlation of radiographic patellar measurements and post-operative AKP remains controversial. The purpose of this study was to determine whether any radiographic measurements can predict anterior knee pain after TKA. Methods. We performed a retrospective analysis of data on 343 patients who underwent a primary unilateral TKA between 2009–2012 at a single institution. Post-operative radiographs were evaluated with standing anteroposterior, lateral, and merchant views. Radiographic assessment was performed to assess posterior offset, Insall Salvati ratio, Blackburne, PP angle, Patella thickness, Congruence angle, Patella tilt, and patella displacement. Clinical function was assessed by the Kujala anterior knee pain scale at a minimum of 5 years. Patients were asked if they currently had anterior knee pain post-operatively by responding “yes” or “no.” There were 264 females and 79 males; the mean age at surgery was 64.2 ± 9.7 (range, 42–92 years) years; the mean BMI 31±5.8 kg/m. 2. (range, 18.8–49 kg/m. 2. ). Results. Of the 343 patients, 46 patients (13.4%) patients suffered persistent AKP at a minimum 5 years follow-up. Radiographic measurements were performed. Although we had large variations in congruence angle, patellar tilt and patellar displacement, these variations had no correlation with anterior knee pain (p=0.885). We were not able to detect statistical significance among clinical outcome Kujala score and patient reported AKP (p=0.713) at minimum 5 year follow-up. Discussion. Persistent anterior knee pain is troubling to patients and surgeons. Clinicians often get concerned when they see variability in these radiographic findings. Our findings suggest that variations in radiographic parameters do not predict anterior knee pain following total knee replacement surgery. For figures, tables, or references, please contact authors directly