Antero-posterior (AP) pelvis and lateral x-rays are routinely prescribed for the positional diagnosis of proximal femoral fractures, however; the usefulness of the lateral x-ray has not been previously presented in the literature. In addition, the clinical advantage of internally rotated AP views has also not been tested. This study aims to define the value of the lateral x-ray, and the internally rotated AP view, in the assessment and treatment planning of proximal femoral fractures. X-rays from 359 consecutive patients with proximal femoral fractures were divided into: ‘un-positioned’ AP (greater trochanter overlying the lateral femoral neck), clear neck AP (internally rotated to show the lateral femoral neck), and lateral views. Three blinded reviewers independently assessed the x-rays in sequence and noted the positional diagnosis and displacement. This was then compared with the intra-operative diagnosis used as gold standard. The addition of a lateral x-ray to an AP view significantly increased the rate of the correct diagnosis made by the reviewers when compared to an AP view alone, in intracapsular fractures only (p < 0.013), but not for extracapsular fractures (p = 0.27). The use of clear neck AP views did not increase the rate of correctly diagnosing the type of fracture when compared to unpositioned AP views. This applies for both intracapsular (p = 0.57), and extracapsular fractures (p < 0.823). Although orthopaedic rote dictates that every fracture should be visualised in two views, this study has shown with that for the majority of hip fractures one view is adequate and safe. The lateral x-ray is only required for intracapsular fractures that appear undisplaced on the AP view and should not be performed routinely. Specially positioned AP views are not required and should be avoided due to the unnecessary pain caused and the needless cost

Aims. Cross-table lateral (CTL) radiographs are commonly used to measure acetabular component anteversion after total hip arthroplasty (THA). The CTL measurements may differ by > 10° from CT scan measurements but the reasons for this discrepancy are poorly understood. Anteversion measurements from CTL radiographs and CT scans are compared to identify spinopelvic parameters predictive of inaccuracy. Methods. THA patients (n = 47; 27 males, 20 females; mean age 62.9 years (SD 6.95)) with preoperative spinopelvic mobility, radiological analysis, and postoperative CT scans were retrospectively reviewed. Acetabular component anteversion was measured on postoperative CTL radiographs and CT scans using 3D reconstructions of the pelvis. Two cohorts were identified based on a CTL-CT error of ≥ 10° (n = 11) or < 10° (n = 36). Spinopelvic mobility parameters were compared using independent-samples t-tests. Correlation between error and mobility parameters were assessed with Pearson’s coefficient. Results. Patients with CTL error > 10° (10° to 14°) had stiffer lumbar spines with less mean lumbar flexion (38.9°(SD 11.6°) vs 47.4° (SD 13.1°); p = 0.030), different sagittal balance measured by pelvic incidence-lumbar lordosis mismatch (5.9° (SD 18.8°) vs -1.7° (SD 9.8°); p = 0.042), more pelvic extension when seated (pelvic tilt -9.7° (SD 14.1°) vs -2.2° (SD 13.2°); p = 0.050), and greater change in pelvic tilt between supine and seated positions (12.6° (SD 12.1°) vs 4.7° (SD 12.5°); p = 0.036). The CTL measurement error showed a positive correlation with increased CTL anteversion (r = 0.5; p = 0.001), standing lordosis (r = 0.23; p = 0.050), seated lordosis (r = 0.4; p = 0.009), and pelvic tilt change between supine and step-up positions (r = 0.34; p = 0.010). Conclusion. Differences in spinopelvic mobility may explain the variability of acetabular anteversion measurements made on CTL radiographs. Patients with stiff spines and increased compensatory pelvic movement have less accurate measurements on CTL radiographs. Flexion of the contralateral hip is required to obtain clear CTL radiographs. In patients with lumbar stiffness, this movement may extend the pelvis and increase anteversion of the acetabulum on CTL views. Reliable analysis of acetabular component anteversion in this patient population may require advanced imaging with a CT scan. Cite this article: Bone Joint J 2021;103-B(7 Supple B):59–65

The purpose of this study was to devise a simple but reliable radiological method of identifying a lumbosacral transitional vertebra (LSTV) with a solid bony bridge on sagittal MRI, which could then be applied to a lateral radiograph. The vertical mid-vertebral angle (VMVA) and the vertical anterior vertebral angle (VAVA) of the three most caudal segments of the lumbar spine were measured on MRI and/or on a lateral radiograph in 92 patients with a LSTV and 94 controls, and the differences per segment (Diff-VMVA and Diff-VAVA) were calculated. The Diff-VMVA of the two most caudal vertebrae was significantly higher in the control group (25° (. sd. 8) than in patients with a LSTV (type 2a+b: 16° (. sd. 9), type 3a+b: -9° (. sd. 10), type 4: -5° (. sd. 7); p < 0.001). A Diff-VMVA of ≤ +10° identified a LSTV with a solid bony bridge (type 3+4) with a sensitivity of 100% and a specificity of 89% on MRI and a sensitivity of 94% and a specificity of 74% on a lateral radiograph. A sensitivity of 100% could be achieved with a cut-off value of 28° for the Diff-VAVA, but with a lower specificity (76%) on MRI than with Diff-VMVA. Using this simple method (Diff-VMVA ≤ +10°), solid bony bridging of the posterior elements of a LSTV, and therefore the first adjacent mobile segment, can be easily identified without the need for additional imaging. Cite this article: Bone Joint J 2013;95-B:1533–7

Introduction. Patients with abnormal spinopelvic mobility are at increased risk for hip instability. Measuring the change in sacral slope (ΔSS) with standing and seated lateral radiographs is commonly used to determine spinopelvic mobility pre-operatively. Sacral slope should decrease at least 10 degrees to demonstrate adequate accommodation. Accommodation of <10 deg necessitates acetabular component position change or use of a dual mobility implant. There is potential for different ΔSS measurements in the same patient based on sitting posture. Methods. 78 patients who underwent THA were reviewed to quantify the variability in pre-operative spinopelvic mobility when two different seated positions (relaxed sitting v. pre-rise sitting) were used in the same patient. Results. 34 patients had standardized pre-rise sitting x-rays, while 44 patients had standardized relaxed sitting x-rays. Of the 44 patients with relaxed sitting x-rays, the mean ΔSS (ΔrSS) was 20.4 degrees. No patients exhibited an increase in sacral slope when sitting (ie; reverse accommodation). Of the 34 patients with pre-rise sitting x-rays, the mean pre-rise sit-stand change (ΔprSS) was only 1.85 degrees with 47% (16/34) showing reverse accommodation, actually increasing the seated sacral slope compared to standing sacral slope. 18 patients had both pre-rise and relaxed sitting x-rays. In patients with both seated x-rays, the mean relaxed sit-stand change in sacral slope (ΔrSS) was 18.1 ± 6.1 degrees and only 3.0 ± 10.5 degrees for pre-rise sit-stand (ΔprSS), with a mean ΔSS difference of the 15.1 degrees (p <0.0001). Conclusion. A 15 degrees error could be made in pre-operative planning depending on the seated posture of the patient. Since decisions on component position or use of dual-mobility are made on pre-operative lateral sit-stand radiographs, postural standardization is critical. The relaxed seated radiograph is the preferred posture at the time of the seated lateral radiograph. For any tables or figures, please contact the authors directly

The radiological evaluation of the anterolateral femoral head is an essential tool for the assessment of the cam type of femoroacetabular impingement. CT, MRI and frog lateral plain radiographs have all been suggested as imaging options for this type of lesion. The alpha angle is accepted as a reliable indicator of the cam type of impingement and may also be used as an assessment for the successful operative correction of the cam lesion. We studied the alpha angles of 32 consecutive patients with femoroacetabular impingement. The angle measured on frog lateral radiographs using templating tools was compared with that measured on CT scans in order to assess the reliability of the frog lateral view in analysing the alpha angle in cam impingement. A high interobserver reliability was noted for the assessment of the alpha angle on the frog lateral view with an intraclass correlation coefficient of 0.83. The mean alpha angle measured on the frog lateral view was 58.71° (32° to 83.3°) and that by CT was 65.11° (30° to 102°). A poor intraclass correlation coefficient (0.08) was noted between the measurements using the two systems. The frog lateral plain radiograph is not reliable for measuring the alpha angle. Various factors may be responsible for this such as the projection of the radiograph, the positioning of the patient and the quality of the image. CT may be necessary for accurate measurement of the alpha angle

Aims. Patients with abnormal spinopelvic mobility are at increased risk for instability. Measuring the change in sacral slope (ΔSS) can help determine spinopelvic mobility preoperatively. Sacral slope (SS) should decrease at least 10° to demonstrate adequate posterior pelvic tilt. There is potential for different ΔSS measurements in the same patient based on sitting posture. The purpose of this study was to determine the effect of sitting posture on the ΔSS in patients undergoing total hip arthroplasty (THA). Methods. In total, 51 patients undergoing THA were reviewed to quantify the variability in preoperative spinopelvic mobility when measuring two different sitting positions using SS for planning. Results. A total of 32 patients had standardized relaxed sitting radiographs, while 35 patients had standardized flexed sitting images. Of the 32 patients with relaxed sitting views, the mean ΔSS was 20.7° (SD 8.9°). No patients exhibited an increase in SS during relaxed sitting (i.e. anterior pelvic tilt or so-called reverse accommodation). Of the 35 patients with flexed sitting radiographs, the mean ΔSS was only 2.1° (SD 9.7°) with 16/35 (45.71%) showing anterior pelvic tilt, or so-called reverse accommodation, unexpectedly increasing the sitting SS compared to the standing SS. Overall, 18 patients had both relaxed sitting and flexed sitting radiographs. In patients with both types of sitting radiographs, the mean relaxed sit to stand ΔSS was 18.06° (SD 6.07°), while only a 3.00° (SD 10.53°) ΔSS was noted when flexed sitting. There was a mean ΔSS difference of 15.06° (SD 7.67°) noted in the same patient cohort depending on sitting posture (p < 0.001). Conclusion. A 15° mean difference was noted depending on the sitting posture of the patient. Since decisions on component position can be made on preoperative lateral sit-stand radiographs, postural standardization is crucial. If using ΔSS for preoperative planning, the relaxed sitting radiograph is preferred. Cite this article: Bone Joint J 2020;102-B(7 Supple B):41–46

Background. One of the basic principles in the primary survey of a trauma patient is immobilisation of the cervical spine till cleared of any injury. Lateral cervical spine radiograph is the gold standard initial radiographic assessment. More than often additional radiographs like the Swimmer's view are necessary for adequate visualisation of the cervical spine. How good is the Swimmer's view in visualisation of the cervical spine after an inadequate lateral cervical spine radiograph?. Materials & methods. 100 Swimmer's view radiographs randomly selected over a 2 year period in trauma patients were included for the study. All the patients had inadequate lateral cervical spine radiographs. The radiographs were assessed with regards to their adequacy by a single observer. The criteria for adequacy were adequate visualisation of the C7 body, C7/T1 junction and the soft tissue shadow. Results. Only 55% of the radiographs were adequate. None of the inadequate radiographs provided adequate visualisation of the C7 body and the C7/T1 junction. In 19% radiographs the soft tissue shadow was unclear. Poor exposure accounted for 53% of the inadequacies while overlapping bones accounted for the rest. Conclusion. Clearing the cervical spine prior to removing triple immobilisation is essential in a trauma patient. This needs adequate visualisation from C1 to C7/T1 junction. In our study Swimmer's views did not satisfactorily provide adequate visualisation of the cervical spine in trauma patients. We recommend screening the cervical spine by a CT scan when the cervical spine lateral radiographs and Swimmer's views are inadequate

Aims. The primary aim of this study was to report the radiological outcomes of patients with a dorsally displaced distal radius fracture who were randomized to a moulded cast or surgical fixation with wires following manipulation and closed reduction of their fracture. The secondary aim was to correlate radiological outcomes with patient-reported outcome measures (PROMs) in the year following injury. Methods. Participants were recruited as part of DRAFFT2, a UK multicentre clinical trial. Participants were aged 16 years or over with a dorsally displaced distal radius fracture, and were eligible for the trial if they needed a manipulation of their fracture, as recommended by their treating surgeon. Participants were randomly allocated on a 1:1 ratio to moulded cast or Kirschner wires after manipulation of the fracture in the operating theatre. Standard posteroanterior and lateral radiographs were performed in the radiology department of participating centres at the time of the patient’s initial assessment in the emergency department and six weeks postoperatively. Intraoperative fluoroscopic images taken at the time of fracture reduction were also assessed. Results. Patients treated with surgical fixation with wires had less dorsal angulation of the radius versus those treated in a moulded cast at six weeks after manipulation of the fracture; the mean difference of -4.13° was statistically significant (95% confidence interval 5.82 to -2.45). There was no evidence of a difference in radial shortening. However, there was no correlation between these radiological measurements and PROMs at any timepoint in the 12 months post-injury. Conclusion. For patients with a dorsally displaced distal radius fracture treated with a closed manipulation, surgical fixation with wires leads to less dorsal angulation on radiographs at six weeks compared with patients treated in a moulded plaster cast alone. However, the difference in dorsal angulation was small and did not correlate with patient-reported pain and function. Cite this article: Bone Jt Open 2024;5(2):132–138

Purpose: The purpose of this study is to provide an additional tool to determine the stability of AO 31A2 pertrochanteric hip fractures. This study is based on the lateral hip radiograph, which has been ignored in the current debate over stability. Method: One-hundred and thirty-one patients were identified through medical records with a diagnosis of pertrochanteric hip fracture treated with sliding hip screw from 2003–2008. Thirty-nine patients had AO 31A2 hip fractures, cross-table lateral injury films, intra-operative fluoroscopy and follow-up films. Only 23 had follow-up films beyond discharge. The landmarks of interest were angulation and translation between the femoral shaft and neck on cross-table lateral injury films. The neck was defined in three ways: the anterior cortex, two key points in the anterior cortex and the neck bisector. The most consistent measure was used. Translation of the neck was measured as a percentage of the shaft diameter. Measurements were taken by two blinded researchers with different levels of experience. Film sequence was randomized. The primary outcome was shortening of the sliding hip screw greater than one centimetre. This is the exact midpoint between 0.61 centimetres, which is not associated with reduced patient mobility, and 1.34 centimetres which is associated with reduced patient mobility, as described by Muller-Farber. The hip screw was measured from its tip to the point it enters the barrel. The diameter of the hip screw was known and provided scale. The measurement from intra-operative fluoroscopy films with the leg in traction, represented zero shortening. Results: The average follow up was 190 days. Using the neck bisector to measure angulation was most consistent (95% of measurements available versus 89% and 88% with other methods). More than 30° angulation and/or 30% translation on the lateral predicted shortening greater than one centimetre with 91% specificity and 33% sensitivity. The average shortening in this group was 1.6 centimeters, which is greater than shortening associated with reduced patient mobility (1.34 centimeters). Agreement between two researchers was 91% and considered “substantial” (kappa 0.71) as per Landis and Koch criteria. Conclusion: This is a highly specific and reproducible tool to detect a subset of AO 31A2 hip fractures which acquire unwanted collapse if treated with a sliding hip screw. This information adds clarity to the debate over stability of some AO 31A2 fracture cases, at no additional cost for the surgeon and facility. The “30/30 rule” (30° angulation and 30% translation) should not be used in isolation due to low sensitivity. Other factors may affect shortening, such as the degree of comminution and the antero-posterior film should still be considered

Aims. The aim of this study was to assess the prognostic value of the modified three-group Stulberg classification, which is based on the sphericity of the femoral head, in patients with Perthes’ disease. Methods. A total of 88 patients were followed from the time of diagnosis until a mean follow-up of 21 years. Anteroposterior pelvic and frog-leg lateral radiographs were obtained at diagnosis and at follow-up of one, five, and 21 years. At the five- and 21-year follow-up, the femoral heads were classified using a modified three-group Stulberg classification (round, ovoid, or flat femoral head). Further radiological endpoints at long-term follow-up were osteoarthritis (OA) of the hip and the requirement for total hip arthroplasty (THA). Results. There were 71 males (81%) and 17 females. A total of 13 patients had bilateral Perthes’ disease; thus 101 hips were analyzed. At five-year follow-up, 37 hips were round, 38 ovoid, and 26 flat. At that time, 66 hips (65%) were healed and 91 (90%) were skeletally immature. At long-term follow-up, when the mean age of the patients was 28 years (24 to 34), 20 hips had an unsatisfactory outcome (seven had OA and 13 had required THA). There was a strongly significant association between the modified Stulberg classification applied atfive-year follow-up and an unsatisfactory outcome at long-term follow-up (p < 0.001). Between the five- and 21-year follow-up, 67 hips (76%) stayed in their respective modified Stulberg group, indicating a strongly significant association between the Stulberg classifications at these follow-ups (p < 0.001). Conclusion. The modified Stulberg classification is a strong predictor of long-term radiological outcome in patients with Perthes’ disease. It can be applied at the healing stage, which is usually reached five years after the diagnosis is made and before skeletal maturity. Cite this article: Bone Joint J 2021;103-B(12):1815–1820

Aims. Pelvic tilt (PT) can significantly change the functional orientation of the acetabular component and may differ markedly between patients undergoing total hip arthroplasty (THA). Patients with stiff spines who have little change in PT are considered at high risk for instability following THA. Femoral component position also contributes to the limits of impingement-free range of motion (ROM), but has been less studied. Little is known about the impact of combined anteversion on risk of impingement with changing pelvic position. Methods. We used a virtual hip ROM (vROM) tool to investigate whether there is an ideal functional combined anteversion for reduced risk of hip impingement. We collected PT information from functional lateral radiographs (standing and sitting) and a supine CT scan, which was then input into the vROM tool. We developed a novel vROM scoring system, considering both seated flexion and standing extension manoeuvres, to quantify whether hips had limited ROM and then correlated the vROM score to component position. Results. The vast majority of THA planned with standing combined anteversion between 30° to 50° and sitting combined anteversion between 45° to 65° had a vROM score > 99%, while the majority of vROM scores less than 99% were outside of this zone. The range of PT in supine, standing, and sitting positions varied widely between patients. Patients who had little change in PT from standing to sitting positions had decreased hip vROM. Conclusion. It has been shown previously that an individual’s unique spinopelvic alignment influences functional cup anteversion. But functional combined anteversion, which also considers stem position, should be used to identify an ideal THA position for impingement-free ROM. We found a functional combined anteversion zone for THA that may be used moving forward to place total hip components. Cite this article: Bone Jt Open 2021;2(10):834–841

Aims

In this study, we aimed to visualize the spatial distribution characteristics of femoral head necrosis using a novel measurement method.

Aims. Eight-plates are used to correct varus-valgus deformity (VVD) or limb-length discrepancy (LLD) in children and adolescents. It was reported that these implants might create a bony deformity within the knee joint by change of the roof angle (RA) after epiphysiodesis of the proximal tibia following a radiological assessment limited to anteroposterior (AP) radiographs. The aim of this study was to analyze the RA, complemented with lateral knee radiographs, with focus on the tibial slope (TS) and the degree of deformity correction. Methods. A retrospective, single-centre study was conducted. The treatment group (n = 64 knees in 44 patients) was subclassified according to the implant location in two groups: 1) medial hemiepiphysiodesis; and 2) lateral hemiepiphysiodesis. A third control group consisted of 25 untreated knees. The limb axes and RA were measured on long standing AP leg radiographs. Lateral radiographs of 40 knees were available for TS analysis. The mean age of the patients was 10.6 years (4 to 15) in the treatment group and 8.4 years (4 to 14) in the control group. Implants were removed after a mean 1.2 years (0.5 to 3). Results. No significant differences in RA (p = 0.174) and TS (p = 0.787) were observed. The limb axes were significantly corrected in patients with VVD (p < 0.001). The change in tibial slope (∆TS) did not correlate (r = -0.026; p = 0.885) to the plate’s position on the physis when assessed by lateral radiographs. Conclusion. We were not able to confirm the reported change in the bony morphology of the proximal tibia on AP radiographs in our patient population. In addition, no significant change in TS was detected on the lateral radiographs. A significant correction of the VVD in the lower limb axes was evident. Position of the implant did not correlate with TS change. Therefore, eight-plate epiphysiodesis is a safe and effective procedure for correcting VVD in children without disturbing the knee joint morphology. Cite this article: Bone Joint J 2020;102-B(10):1412–1418

This study was conducted to investigate the characteristics, complications, radiologic features and clinical course of patients undergoing reduction of forearm fractures in order to better inform patient prognosis and postoperative management. We conducted a retrospective cohort study of 1079 pediatric patients treated for forearm fractures between January 2014 and September 2021 in a 327 bed regional medical center. A preoperative radiological assessment and chart review was performed. Percent fracture displacement, location, orientation, comonution, fracture line visibility and angle of angulation were determined by AP and lateral radiographs. Percent fracture displacement was derived by: (Displacement of Bone Shafts / Diameter) x 100% = %Fracture Displacement. Angle of angulation and percent fracture displacement were calculated by averaging AP and lateral radiograph measurements. 80 cases, averaging 13.5±8.3 years, were identified as having a complete fracture of the radius and/or ulna with 69 receiving closed reduction and 11 receiving fixation via an intramedullary device or percutaneous pinning. Eight patients (10%) experienced complications with four resulting in a refracture and four resulting in significant loss of reduction (LOR) without refracture. Fractures in the proximal ⅔s of the radius were associated with a significant increase in complications compared to fractures in the distal ⅓ of the radius (31.6% vs 3.4%) (P=.000428). Likewise, a higher percent fracture displacement was associated with a decreased risk of complications (28.7% vs 5.9% displacement)(P=0.0403). No elevated risk of complications was found based on fracture orientation, angulation, fracture line visibility, forearm bone(s) fractured, sex, age or arm affected. Our result highlights radius fracture location and percent fracture displacement as markers with prognostic value following forearm fracture. These measurements are simply calculated via pre-reduction radiographs, providing an efficient method of informing risk of complications following forearm fracture

Aims. To determine the effectiveness of prone traction radiographs in predicting postoperative slip distance, slip angle, changes in disc height, and lordosis after surgery for degenerative spondylolisthesis of the lumbar spine. Methods. A total of 63 consecutive patients with a degenerative spondylolisthesis and preoperative prone traction radiographs obtained since 2010 were studied. Slip distance, slip angle, disc height, segmental lordosis, and global lordosis (L1 to S1) were measured on preoperative lateral standing radiographs, flexion-extension lateral radiographs, prone traction lateral radiographs, and postoperative lateral standing radiographs. Patients were divided into two groups: posterolateral fusion or posterolateral fusion with interbody fusion. Results. The mean changes in segmental lordosis and global lordosis were 7.1° (SD 6.7°) and 2.9° (SD 9.9°) respectively for the interbody fusion group, and 0.8° (SD 5.1°) and -0.4° (SD 10.1°) respectively for the posterolateral fusion-only group. Segmental lordosis (ρ = 0.794, p < 0.001) corrected by interbody fusion correlated best with prone traction radiographs. Global lumbar lordosis (ρ = 0.788, p < 0.001) correlated best with the interbody fusion group and preoperative lateral standing radiographs. The least difference in slip distance (-0.3 mm (SD 1.7 mm), p < 0.001), slip angle (0.9° (SD 5.2°), p < 0.001), and disc height (0.02 mm (SD 2.4 mm), p < 0.001) was seen between prone traction and postoperative radiographs. Regression analyses suggested that prone traction parameters best predicted correction of slip distance (Corrected Akaike’s Information Criterion (AICc) = 37.336) and disc height (AICc = 58.096), while correction of slip angle (AICc = 26.453) was best predicted by extension radiographs. Receiver operating characteristic (ROC) cut-off showed, with 68.3% sensitivity and 64.5% specificity, that to achieve a 3.0° increase in segmental lordotic angle, patients with a prone traction disc height of 8.5 mm needed an interbody fusion. Conclusion. Prone traction radiographs best predict the slip distance and disc height correction achieved by interbody fusion for lumbar degenerative spondylolisthesis. To achieve this maximum correction, interbody fusion should be undertaken if a disc height of more than 8.5 mm is attained on preoperative prone traction radiographs. Level of Evidence: Level II Prognostic Study. Cite this article: Bone Joint J 2020;102-B(8):1062–1071

Aims. The aim of the study was to compare two methods of calculating pelvic incidence (PI) and pelvic tilt (PT), either by using the femoral heads or acetabular domes to determine the bicoxofemoral axis, in patients with unilateral or bilateral primary hip osteoarthritis (OA). Methods. PI and PT were measured on standing lateral radiographs of the spine in two groups: 50 patients with unilateral (Group I) and 50 patients with bilateral hip OA (Group II), using the femoral heads or acetabular domes to define the bicoxofemoral axis. Agreement between the methods was determined by intraclass correlation coefficient (ICC) and the standard error of measurement (SEm). The intraobserver reproducibility and interobserver reliability of the two methods were analyzed on 31 radiographs in both groups to calculate ICC and SEm. Results. In both groups, excellent agreement between the two methods was obtained, with ICC of 0.99 and SEm 0.3° for Group I, and ICC 0.99 and SEm 0.4° for Group II. The intraobserver reproducibility was excellent for both methods in both groups, with an ICC of at least 0.97 and SEm not exceeding 0.8°. The study also revealed excellent interobserver reliability for both methods in both groups, with ICC 0.99 and SEm 0.5° or less. Conclusion. Either the femoral heads or acetabular domes can be used to define the bicoxofemoral axis on the lateral standing radiographs of the spine for measuring PI and PT in patients with idiopathic unilateral or bilateral hip OA. Cite this article: Bone Joint J 2021;103-B(8):1345–1350

Aims. Excessive posterior pelvic tilt (PT) may increase the risk of anterior instability after total hip arthroplasty (THA). The aim of this study was to investigate the changes in PT occurring from the preoperative supine to postoperative standing position following THA, and identify factors associated with significant changes in PT. Methods. Supine PT was measured on preoperative CT scans and standing PT was measured on preoperative and one-year postoperative standing lateral radiographs in 933 patients who underwent primary THA. Negative values indicate posterior PT. Patients with > 13° of posterior PT from preoperative supine to postoperative standing (ΔPT ≤ -13°) radiographs, which corresponds to approximately a 10° increase in functional anteversion of the acetabular component, were compared with patients with less change (ΔPT > -13°). Logistic regression analysis was used to assess preoperative demographic and spinopelvic parameters predictive of PT changes of ≤ -13°. The area under receiver operating characteristic curve (AUC) determined the diagnostic accuracy of the predictive factors. Results. PT changed from a mean of 3.8° (SD 6.0°)) preoperatively to -3.5° (SD 6.9°) postoperatively, a mean change of -7.4 (SD 4.5°; p < 0.001). A total of 95 patients (10.2%) had ≤ -13° change in PT from preoperative supine to postoperative standing. The strongest predictive preoperative factors of large changes in PT (≤ -13°) from preoperative supine to postoperative standing were a large posterior change in PT from supine to standing, increased supine PT, and decreased standing PT (p < 0.001). Flexed-seated PT (p = 0.006) and female sex (p = 0.045) were weaker significant predictive factors. When including all predictive factors, the accuracy of the AUC prediction was 84.9%, with 83.5% sensitivity and 71.2% specificity. Conclusion. A total of 10% of patients had > 13° of posterior PT postoperatively compared with their supine pelvic position, resulting in an increased functional anteversion of > 10°. The strongest predictive factors of changes in postoperative PT were the preoperative supine-to-standing differences, the anterior supine PT, and the posterior standing PT. Surgeons who introduce the acetabular component with the patient supine using an anterior approach should be aware of the potentially large increase in functional anteversion occurring in these patients. Cite this article: Bone Joint J 2024;106-B(3 Supple A):74–80

Aims. This study aims to determine the proportion of patients with end-stage knee osteoarthritis (OA) possibly suitable for partial (PKA) or combined partial knee arthroplasty (CPKA) according to patterns of full-thickness cartilage loss and anterior cruciate ligament (ACL) status. Methods. A cross-sectional analysis of 300 consecutive patients (mean age 69 years (SD 9.5, 44 to 91), mean body mass index (BMI) 30.6 (SD 5.5, 20 to 53), 178 female (59.3%)) undergoing total knee arthroplasty (TKA) for Kellgren-Lawrence grade ≥ 3 knee OA was conducted. The point of maximal tibial bone loss on preoperative lateral radiographs was determined as a percentage of the tibial diameter. At surgery, Lachman’s test and ACL status were recorded. The presence of full-thickness cartilage loss within 16 articular surface regions (two patella, eight femoral, six tibial) was recorded. Results. According to articular cartilage loss and ACL status, 195/293 (67%) were suitable for PKA or CPKA: medial unicompartmental knee arthroplasty (UKA) 97/293 (33%); lateral UKA 25 (9%); medial bicompartmental arthroplasty 31 (11%); lateral bicompartmental arthroplasty 12 (4%); bicondylar-UKA 23 (8%); and patellofemoral arthroplasty (PFA) seven (2%). The ACL was intact in 166 (55%), frayed in 82 (27%), disrupted in 12 (4%), and absent in 33 (11%). Lachman testing was specific (97%) but poorly sensitive (38%) for disrupted/absent ACLs. The point of maximal tibial bone loss showed good interclass correlation (ICC 0.797, 0.73 to 0.85 95% confidence interval (CI); p < 0.001) and was more posterior when the ACL was absent. Maximum tibial bone loss occurring at > 55% of the anterior to posterior distance predicted ACL absence with 93% sensitivity and 91% specificity (area under the curve 0.97 (0.94 to 0.99 95% CI; p < 0.001). Conclusion. ACL status can be reliably determined from a lateral radiograph using the location of maximal tibial bone loss. According to regions of cartilage loss and ACL status, two-thirds of patients with end-stage knee OA could potentially be treated with PKA or CPKA. Cite this article: Bone Joint J 2020;102-B(6):716–726

Aims. The aim of this study was to evaluate the reliability and validity of a patient-specific algorithm which we developed for predicting changes in sagittal pelvic tilt after total hip arthroplasty (THA). Methods. This retrospective study included 143 patients who underwent 171 THAs between April 2019 and October 2020 and had full-body lateral radiographs preoperatively and at one year postoperatively. We measured the pelvic incidence (PI), the sagittal vertical axis (SVA), pelvic tilt, sacral slope (SS), lumbar lordosis (LL), and thoracic kyphosis to classify patients into types A, B1, B2, B3, and C. The change of pelvic tilt was predicted according to the normal range of SVA (0 mm to 50 mm) for types A, B1, B2, and B3, and based on the absolute value of one-third of the PI-LL mismatch for type C patients. The reliability of the classification of the patients and the prediction of the change of pelvic tilt were assessed using kappa values and intraclass correlation coefficients (ICCs), respectively. Validity was assessed using the overall mean error and mean absolute error (MAE) for the prediction of the change of pelvic tilt. Results. The kappa values were 0.927 (95% confidence interval (CI) 0.861 to 0.992) and 0.945 (95% CI 0.903 to 0.988) for the inter- and intraobserver reliabilities, respectively, and the ICCs ranged from 0.919 to 0.997. The overall mean error and MAE for the prediction of the change of pelvic tilt were -0.3° (SD 3.6°) and 2.8° (SD 2.4°), respectively. The overall absolute change of pelvic tilt was 5.0° (SD 4.1°). Pre- and postoperative values and changes in pelvic tilt, SVA, SS, and LL varied significantly among the five types of patient. Conclusion. We found that the proposed algorithm was reliable and valid for predicting the standing pelvic tilt after THA. Cite this article: Bone Joint J 2024;106-B(1):19–27

Aims. The aim of this study was to evaluate the ability of a machine-learning algorithm to diagnose prosthetic loosening from preoperative radiographs and to investigate the inputs that might improve its performance. Methods. A group of 697 patients underwent a first-time revision of a total hip (THA) or total knee arthroplasty (TKA) at our institution between 2012 and 2018. Preoperative anteroposterior (AP) and lateral radiographs, and historical and comorbidity information were collected from their electronic records. Each patient was defined as having loose or fixed components based on the operation notes. We trained a series of convolutional neural network (CNN) models to predict a diagnosis of loosening at the time of surgery from the preoperative radiographs. We then added historical data about the patients to the best performing model to create a final model and tested it on an independent dataset. Results. The convolutional neural network we built performed well when detecting loosening from radiographs alone. The first model built de novo with only the radiological image as input had an accuracy of 70%. The final model, which was built by fine-tuning a publicly available model named DenseNet, combining the AP and lateral radiographs, and incorporating information from the patient’s history, had an accuracy, sensitivity, and specificity of 88.3%, 70.2%, and 95.6% on the independent test dataset. It performed better for cases of revision THA with an accuracy of 90.1%, than for cases of revision TKA with an accuracy of 85.8%. Conclusion. This study showed that machine learning can detect prosthetic loosening from radiographs. Its accuracy is enhanced when using highly trained public algorithms, and when adding clinical data to the algorithm. While this algorithm may not be sufficient in its present state of development as a standalone metric of loosening, it is currently a useful augment for clinical decision making. Cite this article: Bone Joint J 2020;102-B(6 Supple A):101–106