Postoperative Computed Tomography Measurements Research Articles

Imageless navigation system (Naviswiss) provides accurate component position in total hip arthroplasty with lateral decubitus position for end-stage hip osteoarthritis: a prospective cohort study with CT-validation

AimsThe Naviswiss system (Naviswiss AG, Brugg, Switzerland) is a handheld imageless navigation device used to improve the accuracy of implant positioning in total hip arthroplasty (THA). However, clinical data for leg length discrepancy and femoral offset is lacking, and the validity of the system has not been reported for patients undergoing THA in the lateral decubitus position. This study aimed to report the accuracy of the device in this patient population.MethodsPatients underwent THA in the lateral decubitus position performed by a single surgeon. Component position measured by the device intraoperatively was compared to postoperative measurements on computed tomography (CT) scans. Agreement between the navigation system and postoperative measurements was reported for acetabular cup inclination, acetabular cup version, femoral offset, and leg length discrepancy.ResultsThirty-three patients were included in the analysis. The mean difference between intraoperative and postoperative CT measurements was within 2° for angular measurements and 2 mm for leg length. Absolute differences in the two indices were up to 4° and 3 mm. The mean bias was 1°–2° overestimation for cup orientation and up to 2 mm overestimation for leg length change. However, 95% limits of agreement did not exceed absolute thresholds of 10° and 10 mm, especially after correction for bias. One case (3%) was declared intraoperatively for issues with fixation on the greater trochanter.ConclusionsThe accuracy of the Naviswiss system falls within clinically acceptable recommendations for acetabular cup placement, femoral offset, and leg length for total hip arthroplasty with a anterolateral approach in lateral decubitus position. The system could be further improved with regression-based bias correction.

CT validation of intraoperative imageless navigation (Naviswiss) for component positioning accuracy in primary total hip arthroplasty in supine patient position: a prospective observational cohort study in a single-surgeon practice

BackgroundThe aim of this study was to report on the validity of the Naviswiss handheld image-free navigation device for accurate intraoperative measurement of THA component positioning, in comparison with the three-dimensional (3D) reconstruction of computed tomography (CT) images as the gold standard.MethodsA series of patients presenting to a single-surgeon clinic with end-stage hip osteoarthritis received primary hip arthroplasty with the anterolateral muscle-sparing surgical approach in the supine position. Imageless navigation was applied during the procedure with bone-mounted trackers applied to the greater trochanter and ASIS. Patients underwent routine CT scans before and after surgery and these were analyzed by using three-dimensional reconstruction to generate cup orientation, offset and leg length changes, which were compared to the intraoperative measurements provided by the navigation system. Estimates of agreement between the intraoperative and image-derived measurements were assessed with and without correction for bias and declared cases with potential measurement issues.ResultsThe mean difference between intraoperative and postoperative CT measurements was within 2° for angular measurements and 2 mm for leg length. Absolute differences for the two indices were between 5° and 4 mm. Mean bias was 1.9°–3.6° underestimation for cup orientation and up to 2 mm overestimation for leg length change, but absolute thresholds of 10° and 10 mm were not exceeded by 95% limits of agreement (LOA), especially after correction for bias. Four cases (12%) were declared intraoperatively for issues with fixation on the greater trochanter. Inclusion of these cases generated acceptable accuracy overall and their omission failed to improve between-case variability in accuracy or LOA for both offset and leg length.ConclusionsThe accuracy of the Naviswiss system applied during primary THA in a supine position and anterolateral surgical approach falls within clinically acceptable recommendations for acetabular cup placement, femoral offset, and length. With refinements to surgical technique to adapt to the navigation hardware, the system could be further improved with regression-based bias correction.Trial registrationRegistered with the Australian New Zealand Clinical Trials Registry (ACTRN12618000317291)

Influences of Increasing Pedicle Screw Diameter on Widening Vertebral Pedicle Size during Surgery in Spinal Deformities in Children and Adolescents without Higher Risk of Pedicle and Vertebral Breaches.

A very common technique for treating spinal deformities in children and adolescents is the use of segmental screws. In order to obtain proper stability and the best possible correction, the screws must first be precisely inserted. Additional factors influencing the quality and success of the operation are the size and quality of the bone, the skills of the surgeon, and biomechanical factors, i.e., the width and length of the screws used during surgery. Our study was focused on evaluating the effect of increasing the diameter of the instrumented pedicles by pedicle screws and assessing the safety of expanding these pedicles with screws of various sizes in children with spinal deformities during the growth period, using preoperative magnetic resonance imaging and postoperative computed tomography (CT) to assess and compare preoperative size measurements from MRI to postoperative CT measurements. We obtained data for evaluation from the available medical records and treatment histories of patients aged 2 to 18 who underwent surgical treatment of spinal deformities in the years 2016-2023. In 230 patients (28 male and 202 female), 7954 vertebral bodies were scanned by preoperative MRI, and 5080 pedicle screws were inserted during surgery, which were then assessed by postoperative CT scan. For the most accurate assessment, patients were classified into three age groups: 2-5 years (Group 1), 6-10 years (Group 2), and 11-18 years (Group 3). In addition, we studied implant subgroups: vertebral bodies with inserted pedicles of screw sizes 5.0 mm and 5.5 mm (Group S), and pedicles of screw sizes 6.0 mm, 6.5 mm, and 7.0 mm (Group L). The morphology of pedicles (Lenke classification) analyzed before surgery using MRI was 55.2% type A, 33.8% type B, 4.7% type C, and 6.3% type D. The postoperative lateral and medial breaches were noted, and these did not cause any complications requiring revision surgery. The mean pedicle diameter before surgery for T1-L5 vertebral pedicles was between 3.79 (1.44) mm and 5.68 (1.64) mm. The mean expanding diameter of pedicles after surgery for T1-L5 vertebral pedicles ranged from 1.90 (0.39) mm to 2.92 (0.28) mm, which corresponds to the extension of the pedicle diameter in the mean range of 47% (4.1)-71% (3.0). We noted that the mean vertebral pedicle expansion was 49% in Group 1, 52% in Group 2, and 62% in Group 3 (N.S.), and the mean expansion for 7.0 mm screw pedicles was 78%. Our study confirms that there is a wide range of expansion of the vertebral pedicle during screw insertion (up to 78%) with a low risk of lateral or medial breaches and without an increased risk of complications. The larger the diameter of the screw inserted into the pedicle, the more the pedicle expands. Pedicle measurements by preoperative MRI may be helpful for sufficient reliability in preoperative planning.

Error of intraoperative measurement of stem anteversion is decreased by measuring in neutral hip position during total hip arthroplasty

BackgroundIntraoperative stem anteversion, which is the angle between the lower leg axis and the trial-stem axis with hip flexion and adduction, is generally evaluated by the surgeon's visual estimation during total hip arthroplasty (THA). However, the conventional approach can be influenced by knee osteoarthritis or uncertain surgeon's observation point. Therefore, we developed a new method for measuring the stem anteversion angle in the neutral hip position using an original rod attached to the trial-stem perpendicular to the long axis and parallel to the stem neck. This study aimed to assess the accuracy of our method in comparison with the conventional method of measuring intraoperative stem anteversion angle. MethodsWe measured the intraoperative stem anteversion angle in consecutive 106 hips of 106 patients who underwent cementless primary THA with a tapered wedge stem. Absolute error in the stem anteversion angle was expressed as the difference between intraoperative (common vs. neutral hip positions) and postoperative computed tomography measurements, i.e., true stem anteversion. Additionally, we investigated the factors affecting these errors. ResultsThe absolute error of measurement was significantly smaller in the neutral hip position than in the common position (3.0° ± 2.5° vs. 8.0° ± 3.9°; p < 0.0001). The factor associated with the error was advanced knee osteoarthritis in the common position, whereas it was not statistically significant in the neutral hip position. ConclusionsThis study suggests that the error in the intraoperative measurement of stem anteversion is decreased by measuring in the neutral hip position during THA.

Restoration of Global Offset and Limb Length in Primary Unilateral Total Hip Arthroplasty When Preoperative Templating is not Applied

Background: Preoperative templating is an essential step before performing any total hip arthroplasty (THA). Restoration of global offset (GO) and limb length (LL) were among the templating purposes. Thus, we aimed to perform THA without preoperative templating based on clinical examination and intra-operative anatomical landmarks to restore hip biomechanics.Patients and Methods: This prospective observational study was conducted on 40 patients with primary THA through the posterior approach. The lesser trochanter was used to determine the level of femoral neck cut, the femoral component insertion depth, and version, along with adjusting the level of the center of the femoral head to the tip of the greater trochanter. The transverse acetabular ligament (TAL) was used as a reference for the acetabular component version and inclination. To optimize the LL, preoperative clinical assessment, intra-operative comparison with the normal side, soft tissue tension, and shuck test were used. GO was adjusted using the depth of acetabulum after reaming, placing the acetabular component fit or 10% overhang from the ridge and gluteus medius muscle tension. Postoperatively, computed tomography (CT) scan was used for measuring the GO (acetabular offset (AO) + femoral offset (FO)) and limb length discrepancy (LLD) and compared to the sound side. Pre and postoperatively, LL was measured using a tape measure from the anterior superior iliac spine (ASIS) to the medial malleolus.Results: Depending on postoperative CT measurements, there was no significant difference between the mean normal and operative GO (P=0.894). The mean LL difference between the two sides was 0.38 cm (P=0.007). Clinically, the mean LLD (comparing the normal side with the operated side preoperatively) was 1.001 cm, while the mean LLD was 0.722 cm (P=0.0455).Conclusions: This study demonstrated that when the preoperative templating step is omitted, depending on intraoperative landmarks, neither the GO nor the AO and FO of the operated side were significantly affected. The mean radiological and clinical postoperative LLD was almost consistent, and the mean difference was &lt; 1 cm, which is within the acceptable range. Do not use abbreviations in abstract and conclusions.

P133. Measuring the radiographic efficacy of indirect decompression following minimally invasive lumbar interbody fusion: a computed tomography (CT) analysis study

<h3>BACKGROUND CONTEXT</h3> The advancement of MIS techniques has led to increased reliance on indirect decompression techniques. The latest generation of MIS TLIF cages are typically expandable cages that restore disc height and achieve ligamentum flavum unbuckling with associated increased central canal area. While prior studies have measured the extent of indirect decompression associated with ALIF and LLIF, the degree of decompression achieved via MIS-TLIF has not been described. <h3>PURPOSE</h3> Assess the degree of indirect decompression following minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). <h3>STUDY DESIGN/SETTING</h3> Single-center, multi-surgeon, retrospective review. <h3>PATIENT SAMPLE</h3> Patients undergoing MIS-TLIF without direct decompression between 3/2017 and 3/2021. Patients were included if they had a pre- and postoperative CT scan. <h3>OUTCOME MEASURES</h3> Pre- and postoperative CT scans were used to measure disc height, foraminal area (left and right) and central canal area at the operative level(s). The most recent postoperative patient reported outcome measures (PROMs) between 6 months and 2 years were used to compare against preoperative values. <h3>METHODS</h3> Postoperative CT was performed at 1-43 months based on surgeon-specific protocols. Both pre- and postoperative CT measurements were performed by two observers. PROMs were collected in a prospectively maintained database. Paired tests were used to compare changes in CT measurements and PROMs. Bivariate analysis was also done to assess correlations between the changes in CT measures and PROMs improvement. <h3>RESULTS</h3> A total of 40 patients (48 operative levels) were assessed; 16 (33.3%) of the subjects were female and 24 (50%) were male. The average age was 56.6 ± 15.9 years. The average length of follow-up was 17.9 ± 7.9 months for PROMs and 13.5 ± 9.3 months for postoperative CT imaging. There were 32 (80%) single-level and 8 (20%) two-level cases, with 23 (47.9%) operated at L4L5 and 25 (52.1%) at L5S1. Disc height, foraminal area, and central canal area all increased significantly (p < 0.001). Mean disc height increased 50%, from 4.2 to 6.3mm. Right sided foraminal area increased 23%, from 144 .5 to 177.8mm2, the left increased 21.4% from 142.8 to 173.4mm2, and the central canal increased 16.4% from 228.6 to 266 mm2. All PROMs except for SF12-MCS (p=0.439) showed a statistically significant improvement (p < 0.05). There was no correlation between each change in PROM and the increase in cross sectional canal area. <h3>CONCLUSIONS</h3> MIS-TLIF provides a significant degree of indirect decompression. Disc height, foraminal area and central canal area were all increased following insertion of the interbody cage via the MIS-TLIF technique. PROMs by 2 years demonstrated a statistically significant improvement. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

CT-based Abdominal Adipose Tissue Area Changes in Patients Undergoing Adrenalectomy Due to Cushing's Syndrome and Non-functioning Adenomas.

The majority of Cushing's syndrome (CS) cases constitute patients with functional adrenal adenomas. In adrenal CS, visceral adipose tissue (VAT) area, VAT/subcutaneous adipose tissue (SAT), and VAT/total adipose tissue (TAT) ratios are expected to decrease in response to adrenalectomy, although no change is expected in non-functioning adrenal adenomas (NFA). To evaluate the changes in VAT, SAT, TAT areas and VAT/SAT, VAT/TAT ratios using computed tomography (CT) in patients who underwent adrenalectomy due to adenomas. Preoperative and postoperative CT of 32 patients (16 with CS and 16 with NFA) were retrospectively evaluated. The VAT, SAT, TAT areas were obtained from CT at the level of L1-2 intervertebral disc space, and the VAT/SAT, VAT/TAT ratios were calculated. The postoperative parameter changes in both groups were evaluated compared to the preoperative values. The level of statistical significance was considered as p<0.05. The time interval between preoperative and postoperative CT measurements were 10.37 months (6-17) in CS and 9.75 months (7-15) in NFA groups (p=073). Preoperative CT indicated that the patients with CS had larger VAT and TAT areas (p=0.03, p=0.02) but SAT remained unchanged (p=0.08). However, postoperative CT revealed that there was no difference between the two groups in terms of VAT, TAT, and SAT areas (p=0.87, p=0.36, p=0.14). Postoperatively, in patients with CS, there was a decrease in VAT and TAT areas (p=0.01 for both) and VAT/SAT and VAT/TAT ratios (p=0.03, p=0.02) but SAT remained unchanged (p=0.10). In patients with NFA, no change was detected in the postoperative SAT, TAT, and VAT areas (p=0.12, p=0.40, p=0.99) or the VAT/SAT and VAT/TAT ratios (p=0.38, p=0.62). Adrenalectomy is an effective treatment method leading to a decrease in the VAT, TAT areas, and VAT/SAT and VAT/TAT ratios in patients with cortisol producing adrenocortical adenoma. Thus, CT facilitates quantitative demonstration of the changes while evaluating the response of these patients to treatment.

Clinical results of a short stem with flat tapered wedge design in primary total hip arthroplasty for hip dysplasia in Asians.

Cementless femoral reconstruction is challenging in hip dysplasia due to deformity of the proximal femur causing insufficient stem fixation and/or inadequate neck anteversion. Strategies to address these problems include the use of a modular stem or a distal fixation stem, but both stems have some characteristic disadvantages. We studied the postoperative clinical outcomes in primary total hip arthroplasty in 257 hips using the flat tapered wedge short femoral stem for hip dysplasia in an Asian population (postoperative follow-up period: 2 years to 6 years and 11 months; mean 4 years and 5 months). We took advantage of the characteristic of high flexibility in stem placement because of its low volume, positioning it while performing some varus/valgus and rotational alignment adjustments. Favorable clinical functional outcomes were obtained, including the radiographic outcome of biological fixation achieved in all stems. Regarding complications, there was no case of split fracture of the femoral calcar region during stem insertion, and the rate of postoperative dislocation was also low at 0.4% (1 case). In the pre- and postoperative computed tomography measurements, the variability in stem anteversion postoperatively was significantly reduced compared to preoperative anatomical anteversion. This flat-shaped short low-volume stem likely has high flexibility in positioning in cases of hip dysplasia and can be easily positioned to avoid fractures while still achieving secure fixation.

CT Validation of Intraoperative Implant Position and Knee Alignment as Determined by the MAKO Total Knee Arthroplasty System.

Robotic-assisted technology in total knee arthroplasty (TKA) aims to increase implantation accuracy, with real-time data being used to estimate intraoperative component alignment. Postoperatively, Perth computed tomography (CT) protocol is a valid measurement technique in determining both femoral and tibial component alignments. The aim of this study was to evaluate the accuracy of intraoperative component alignment by robotic-assisted TKA through CT validation. A total of 33 patients underwent TKA using the MAKO robotic-assisted TKA system. Intraoperative measurements of both femoral and tibial component placements, as well as limb alignment as determined by the MAKO software were recorded. Independent postoperative Perth CT protocol was obtained (n = 29) and compared with intraoperative values. Mean absolute difference between intraoperative and postoperative measurements for the femoral component were 1.17 degrees (1.10) in the coronal plane, 1.79 degrees (1.12) in the sagittal plane, and 1.90 degrees (1.88) in the transverse plane. Mean absolute difference between intraoperative and postoperative measurements for the tibial component were 1.03 degrees (0.76) in the coronal plane and 1.78 degrees (1.20) in the sagittal plane. Mean absolute difference of limb alignment was 1.29 degrees (1.25), with 93.10% of measurements ≤3 degrees of postoperative CT measurements. Overall, intraoperatively measured component alignment as estimated by the MAKO robotic-assisted TKA system is comparable to CT-based measurements.

A Pilot Study of Augmented Reality Technology Applied to the Acetabular Cup Placement During Total Hip Arthroplasty

BackgroundWe developed an acetabular cup placement device, the AR-HIP system, using augmented reality (AR). The AR-HIP system allows the surgeon to view an acetabular cup image superimposed in the surgical field through a smartphone. The smartphone also shows the placement angle of the acetabular cup. This preliminary study was performed to assess the accuracy of the AR-HIP system for acetabular cup placement during total hip arthroplasty (THA). MethodsWe prospectively measured the placement angles using both a goniometer and AR-HIP system in 56 hips of 54 patients undergoing primary THA. We randomly determined the order of intraoperative measurement using the 2 devices. At 3 months after THA, the placement angle of the acetabular cup was measured on computed tomography images. The primary outcome was the absolute value of the difference between intraoperative and postoperative computed tomography measurements. ResultsThe measurement angle using AR-HIP was significantly more accurate in terms of radiographic anteversion than that using a goniometer (2.7° vs 6.8°, respectively; mean difference 4.1°; 95% confidence interval, 3.0-5.2; P < .0001). There was no statistically significant difference in terms of radiographic inclination (2.1° vs 2.6°; mean difference 0.5°; 95% confidence interval, −1.1 to 0.1; P = .13). ConclusionIn this pilot study, the AR-HIP system provided more accurate information regarding acetabular cup placement angle than the conventional method. Further studies are required to confirm the utility of the AR-HIP system as a navigation tool.

The Directive Growth Approach for Nonsyndromic, Unicoronal Craniosynostosis: Patient and Clinical Outcomes.

Deformities of the cranium in patients with nonsyndromic single-suture synostosis occur because of growth restriction at fused sutures and growth over compensation at normal sutures. Traditional surgery includes ostectomies of the synostotic suture to release these restricted areas and osteotomies to enable immediate cranial remodeling. In the process of reshaping the cranium, traditional approaches usually involve obliteration of both the normal functioning suture and the pathologic suture. The directive growth approach (DGA) is a new, simpler, more natural way to repair deformities caused by single-suture cranial synostosis. The DGA works by reversing the original deforming forces by temporarily restricting growth in areas of over compensation and forcing growth in areas of previous synostotic restriction. Most importantly, it preserves a normal functioning suture to allow for improved future cranial growth. Eighteen consecutive nonsyndromic patients with unilateral coronal synostosis were used to illustrate the efficacy of the DGA. Ten patients who underwent DGA treatment were compared with a control group of 8 patients treated with traditional frontal orbital advancement. Postoperative three-dimensional computed tomography (CT) comparison measurements were taken, including bilateral vertical and transverse orbital dimensions, lateral orbital rim to external auditory canal, and forehead measurements from the superior aspect of the orbital rim to the pituitary fossa. The traditional treatment group showed absence of the coronal sutures bilaterally on long-term CT scans. The DGA group showed normal coronal sutures on the unaffected sides. Postoperative CT measurements showed no statistical difference between the 2 techniques (P < 0.05).

Clinical Outcome and Postoperative CT Measurements of Microendoscopic Decompression for Lumbar Spinal Stenosis.

This was a retrospective case series. To retrospectively evaluate the clinical outcome of microendoscopic decompression for lumbar spinal stenosis (LSS) including an evaluation of the extent of decompression using computed tomography. Microendoscopic decompression has been a widely applied procedure to treat LSS with satisfactory outcomes and comparatively fewer complications and revision. However, few reports showed computed tomography (CT) measurements of the lumbar spine to assess the postoperative decompression. This study included 103 patients (55 males and 48 females; mean age, 69 y) who underwent microendoscopic decompression for treatment of LSS between January 2009 and January 2011. All patients underwent preoperative CT and postoperative CT at 6 months and 2 years of follow-up to measure the vertebral canal area and the sagittal diameter of the lateral recess at the outer rim. The Japanese Orthopedic Association (JOA) scale, Oswestry Disability Index, and Visual Analogue Scale were used to evaluate clinical efficacy. The mean vertebral canal area and sagittal diameter of the lateral recess were significantly larger at 6 months and 2 years after surgery compared with 1 day before surgery (P<0.001). The mean JOA scale scores were significantly higher at 6 and 24 months following surgery compared with before surgery (P<0.001). The mean Oswestry Disability Index scores and Visual Analogue Scale scores at 6 months and 2 years after surgery were significantly lower compared with before surgery (both P<0.001). The mean JOA recovery rates at 6 months and 2 years of follow-up were 61% and 64.3%, respectively. The results confirm that microendoscopic decompression for LSS is safe and effective. This study is one of the first to obtain CT measurements of the lumbar spine to assess the postoperative decompression of this procedure.

Application of a computer-assisted surgical navigation system in temporomandibular joint ankylosis surgery: a retrospective study

This retrospective study evaluated the effect of surgical computer-assisted navigation in temporomandibular joint (TMJ) ankylosis gap arthroplasty. Eighteen patients (25 sides) with bony ankylosis who underwent surgical treatment under computer-assisted navigation (navigation group) from May 2011 to April 2013 were assessed, along with 19 such patients (25 sides) treated without computer-assisted navigation (non-navigation group) from March 2009 to April 2011. The navigation group patients underwent surgery with the preservation of ≥3mm bone thickness in the skull base and anterior wall of the external auditory canal. Postoperatively, computed tomography (CT) was used to measure the residual bone thickness in the skull base and anterior wall of the external auditory canal. Maximum mouth opening (MMO) changes were evaluated at >1 year of follow-up. Postoperative CT measurements showed that the lowest skull base thickness in the navigation group was significantly lower than that in the non-navigation group (3.86±1.95mm vs. 6.01±3.07mm, P=0.009). The lowest thicknesses of the anterior wall of the external auditory canal were similar in the two groups. Postoperative follow-up showed similar average MMO in the two groups. Therefore, with the navigation system, TMJ ankylosis gap arthroplasty can achieve more extensive removal of the ankylosed bone, at least towards the skull base, under the premise of ensuring a safety distance of 3mm.

EACMFS Prizes and Awards

To describe a new glenoid fossa bone graft technique, and to evaluate its effect on the stability of stock fossa prosthesis implantation in total alloplastic joint replacement surgery.Eight patients who underwent total joint replacement surgery with a Biomet stock prosthesis (Biomet, Warsaw, IN, USA) from November 2013 to April 2014 were included in this study. ProPlan CMF 1.4 software (Materialise NV, Leuven, Belgium) was used to choose the prosthesis size and place it in the right position. The depth of the fossa was measured, and the osteotomy line was designed to cut the bone which overlapped the fossa prosthesis. A bone graft, taken from the bottom of the articular eminence or the condylar neck, was used to fill in the fossa and make a flat plane in combination with the residual eminence for the positioning of the fossa prosthesis. The stability of the fossa prosthesis was evaluated both intra-operatively and postoperatively with computed tomography (CT) scanning after at least 6 months of follow-up. The bone contact area of the fossa prosthesis and the volume of the grafted bone were measured.Fossa prostheses were intra-operatively stable after bone grafting. All patients had stable occlusion after surgery and at follow-up. Postoperative measurement showed that the bone contact area with the fossa prosthesis increased from 52.8% to 88.5% after bone grafting. Postoperative CT measurements (at an average of 9 months after surgery) showed that the bone graft volume decreased by 11.1%.Bone grafts in the glenoid fossa help to improve the stability of Biomet stock fossa prosthesis implantation.

Lack of agreement between computer navigation and post-operative 2-dimensional computed tomography (CT) measurements for component and limb alignment in total knee arthroplasty (TKA)

BackgroundThe purpose of this study was to assess the degree of mismatch between intraoperative navigation data using imageless computer navigation and post-operative CT scan measurements with respect to bone cuts, component and limb alignment during TKA. MethodsIntraoperative navigation data including bone cut verification and overall limb alignment during TKA was compared to postoperative CT measurements of component and limb alignment according to the Perth protocol. The proportion of cases with mismatch between navigation and CT measurements at two and three degree thresholds was identified. ResultsIn a total sample of 50 primary TKAs, 20% of cases showed a mismatch of more than two degrees between navigation and CT obtained measurements for coronal femoral alignment, 42% for femoral rotation, 16% for tibial component coronal alignment and 32% for overall limb alignment. ConclusionMismatch between intraoperative navigation data and postoperative CT measurements suggests that postoperative CT scan alignment data should be interpreted with caution. A surgeon should consider a multitude of factors when analysing component and limb alignment postoperatively.

Application of fossa bone graft to stabilize stock total joint prosthesis in temporomandibular joint surgery.

To describe a new glenoid fossa bone graft technique, and to evaluate its effect on the stability of stock fossa prosthesis implantation in total alloplastic joint replacement surgery. Eight patients who underwent total joint replacement surgery with a Biomet stock prosthesis (Biomet, Warsaw, IN, USA) from November 2013 to April 2014 were included in this study. ProPlan CMF 1.4 software (Materialise NV, Leuven, Belgium) was used to choose the prosthesis size and place it in the right position. The depth of the fossa was measured, and the osteotomy line was designed to cut the bone which overlapped the fossa prosthesis. A bone graft, taken from the bottom of the articular eminence or the condylar neck, was used to fill in the fossa and make a flat plane in combination with the residual eminence for the positioning of the fossa prosthesis. The stability of the fossa prosthesis was evaluated both intra-operatively and postoperatively with computed tomography (CT) scanning after at least 6 months of follow-up. The bone contact area of the fossa prosthesis and the volume of the grafted bone were measured. Fossa prostheses were intra-operatively stable after bone grafting. All patients had stable occlusion after surgery and at follow-up. Postoperative measurement showed that the bone contact area with the fossa prosthesis increased from 52.8% to 88.5% after bone grafting. Postoperative CT measurements (at an average of 9 months after surgery) showed that the bone graft volume decreased by 11.1%. Bone grafts in the glenoid fossa help to improve the stability of Biomet stock fossa prosthesis implantation.

Degrees of Tolerance in Post-Traumatic Orbital Volume Correction: The Role of Prefabricated Mesh

To identify factors influencing the volumetric correction of orbital fractures, and evaluate the use of prefabricated titanium mesh in their repair. We included patients with unilateral orbital fractures and floor or medial-wall defects, subsequently reconstructed with titanium mesh, and subject to adequate follow-up with multislice, digitalized computed tomography (CT) images. Medical records were reviewed, and demographics, operative details, and postoperative course were recorded as prognostic variables. Moreover, orbital volume, apex-to-globe distance, and orbital rim area were measured using postoperative CT. Univariate analysis and a multiple-regression model were used to identify associated factors. A total of 32 patients fulfilled the inclusion criteria. Postoperative clinical evaluation and CT images were obtained in a mean +/- SD of 12.3 +/- 7.2 months after surgery. Clinically, 20 patients were considered normal (63%), and 12 manifested some ocular dystopia (37%). On postoperative CT, the mesh was in good position in 44% of cases, and in an insufficient position in 56% of cases. There was a significant difference between fractured and normal orbits in relation to orbital volume and apex-globe distance. Clinical evaluation significantly correlated with CT mesh placement, but there was no correlation between clinical evaluation and any of the variables measured on CT. The most important factors influencing postoperative orbital volume correction were type of fracture, affected walls, and use of prefabricated mesh. Volumetric and lineal symmetry between fractured and normal orbits are very difficult to achieve. In this study, postoperative CT measurements did not correlate with subjective clinical assessment. The clinical-radiological disagreement may be explained by measurement accuracy problems, clinical bias, or normal differences between orbits. The most important identified modifiable factor was the use of prefabricated mesh.