Inducible Displacement of a Trabecular Metal Tibial Monoblock Component

Radiostereometric analysis is a highly accurate technique that can be used for measuring micromotion at the bone-implant interface. The purpose of this study was to compare the inducible displacement of the uncemented Trabecular Metal (TM; Zimmer, Warsaw, Ind) tibial monoblock component with that of a cemented implant. Inducible displacement of 14 uncemented TM components and 11 cemented components was measured 24 to 48 months postoperatively. Longitudinal migration of the implants was also measured with radiostereometric analysis at 6, 12, and 24 months postoperatively. The uncemented TM group had significantly lower inducible displacement than the cemented components. Significant correlations were found between longitudinal migration and the inducible displacement tests. The low values of inducible displacement in the TM group indicated good fixation and a promising long-term prognosis.     

Preoperative bone mineral density of the proximal tibia and migration of the tibial component after uncemented total knee arthroplasty

Twenty-two patients with primary osteoarthrosis of the knee all operated on with insertion of an uncemented total knee arthroplasty had a preoperative measurement of bone mineral density (BMD) in the coronal plane of the proximal tibia performed by dual-photon absorptiometry. Postoperatively and with follow-up after 6 weeks (n = 21), 1 year (n = 22), and 3 years (n = 19), radiographs suitable for radiostereometric analysis of the tibial component migration were obtained. One year postoperatively, stress examinations were performed with the aim of measuring inducible displacement of the tibial component. Most of the migration, expressed as maximal total point motion (MTPM), occurred during the first year with an average migration of approximately 1 mm. Regression analysis showed a positive relation between BMD and MTPM after 6 weeks (P = .03, r = .47), 1 year (P = .0005, r = .68), and 3 years (P = .02, r = .54). Inducible displacement did not reveal any significant relation to BMD. MTPM between 1 and 3 years, which is the clinically most important parameter with respect to later loosening of the tibial component, showed a negative relation to BMD (P = .04, r = −.47). Thus, tibial components of knees with preoperative high tibial BMD showed less continuous migration.     

Contact Kinematic Differences Between Gap Balanced vs Measured Resection Techniques for Single Radius Posterior-Stabilized Total Knee Arthroplasty

Background

Measured resection (MR) and gap balancing (GB) are common surgical techniques for total knee arthroplasty (TKA). Controversy has arisen as each conceptually differs in how the knee is balanced through bone and soft tissue management. The objective of the present study was to compare both the frequency of condylar liftoff and the location of femorotibial contact from extension through midflexion between patients undergoing GB or MR TKA.

Effects of Kidney Transplantation on Valvular Heart Diseases

IntroductionIn patients with end-stage renal failure, hypervolemia frequently causes increased cardiac output, especially in patients who are under-dialyzed and those with cardiac decompensation.ObjectiveThis study aimed to examined the effect of kidney transplantation on valvular heart diseases.Patients and methodsThis retrospective data analysis included adult patients (n = 180) who underwent kidney transplantation between February 2015 and June 2018 at the Division of Organ Transplantation, University of Debrecen, Hungary. This study examined the echocardiographic parameters and laboratory results preoperatively and postoperatively (at 6 and 12 months). Statistical analyses were performed using the χ²/Fisher exact tests and Kruskal-Wallis analysis of variance test. P < .05 was considered significant.ResultsNo mitral regurgitation (MR) was observed preoperatively in 27% of the patients, while 62% had grade 1 MR, and 11% had grade 2 MR. Grade 2 MR was reduced from 11% to 2% twelve months after kidney transplantation (P = .03). Valvular calcification was detected preoperatively in 21.5% of the study population but was detected in 25.8% 6 months postoperation and in 35.5% 12 months postoperation (P = .09). At 12-month follow-up, 30.8% of patients without diabetes and 60% (P = .03) of patients with diabetes had valvular calcification.ConclusionSignificant improvement was noted in patients with moderate-stage MR because renal transplantations decrease the volume overload on the heart. After surgical intervention, elevation in the incidence of calcified valves among patients with diabetes was significant compared to patients without diabetes.     

The Fate and Relevance of the Patella in Two-Stage Revision Total Knee Arthroplasty for Periprosthetic Joint Infection

BackgroundIt remains unclear whether reimplantation of a patellar component during a two-stage revision for periprosthetic total knee arthroplasty infection (PJI) affects patient reported outcome measures (PROMs) or implant survivorship. The purpose of this study was to evaluate whether patellar resurfacing during reimplantation confers a functional benefit or increases implant survivorship after two-stage treatment for PJI.MethodsTwo-stage revisions for knee PJI performed by three surgeons at a single tertiary care center were reviewed retrospectively. All original patellar components and cement were removed during resection and the patella was resurfaced whenever feasible during reimplantation. PROMs, implant survivorship, and radiographic measurements (patellar tilt and displacement) were compared between knees reimplanted with a patellar component versus those without a patellar component.ResultsA total of 103 patients met the inclusion criteria. Forty-three patients (41.7%) underwent reimplantation with, and 60 patients (58.3%) without a patellar component. At a mean follow-up of 33.5 months, there were no significant differences in patient demographics or PROMs between groups (P ≥ .156). No significant differences were found in the estimated Kaplan-Meier all-cause, aseptic, or septic survivorship between groups (P ≥ .342) at a maximum of 75 months follow-up. There was no significant difference in the change (pre-resection to post-reimplant) of patellar tilt (P = .504) or displacement (P = .097) between the groups.ConclusionPatellar resurfacing during knee reimplantation does not appear to meaningfully impact postoperative PROMs or survivorship. Given the risk of potential extensor mechanism complications with patellar resurfacing, surgeons may choose to leave the patella without an implant during total knee reimplantation and expect similar clinical outcomes.Level of EvidenceLevel III.     

Tibial Component Migration After Total Knee Arthroplasty With High-Viscosity Bone Cement

BackgroundHigh-viscosity (HV) bone cements have been formulated to offer potentially advantageous handling characteristics. However, alteration in the handling characteristics could influence implant fixation and survival. The primary objective of this study was to use radiostereometric analysis after total knee arthroplasty to assess the migration of the Triathlon tibial component fixed with HV cement (Simplex HV).MethodsTwenty-three patients were followed for two years with radiostereometric analysis examinations at 6 visits. Migration was compared with published thresholds and with a control group from a previously published study from the same center using the same implants fixed with a medium viscosity cement. Inducible displacement was assessed, and Oxford 12 Knee Scores and satisfaction were recorded.ResultsMean maximum total point motion migration reaching 0.40 mm (SD 0.16) at one year, and 0.41mm (SD 0.17) at two years, demonstrating a pattern of stable fixation, below published thresholds of acceptable migration, and not significantly different from the control group. One implant had continuous migration between 1 and 2 years but was clinically asymptomatic. Mean maximum total point motion inducible displacement measured at least one year postoperatively was 0.3 mm (SD 0.12). Mean Oxford 12 Knee Scores improved from 19 (SD 7) preoperatively to 42 (SD 8) 2 years postoperatively.ConclusionsThe use of HV cement demonstrated an acceptable pattern of migration at 2 years, indicating low risk for aseptic loosening.     

Axial and Sagittal Rotation of Cementless Tibial Baseplates Occurs in Bone Under Joint Loading

BackgroundThere has been a recent increase in the use of cementless fixation for primary total knee arthroplasty. While the early results of contemporary cementless implants are promising, understanding the behavior of cementless tibial baseplates under loading remains an ongoing interest. The objective of this study was to identify the pattern of displacement that occurred under loading for a single cementless tibial baseplate design at one year post operation for stable and continuously migrating implants.MethodsThere were 28 subjects from a previous trial of a pegged highly porous cementless tibial baseplate evaluated. Subjects underwent supine radiostereometric exams from two weeks through one year after surgery. At one year, subjects also underwent a standing radiostereometric exam. Fictive points on the tibial baseplate model were used to relate translations to anatomical locations. Migration over time was calculated to determine if subjects displayed stable or continuous migration. The magnitude of inducible displacement between the supine and standing exams was calculated.ResultsInducible displacement patterns were similar between stable and continuously migrating tibial baseplates. Displacements were greatest in the anterior-posterior axis followed by the lateral-medial axis. Correlation of displacements between adjacent fictive points in these axes indicated an axial rotation of the baseplate occurred under loading (r² = 0.689-0.977, P < .001). Less displacement occurred in the superior-inferior axis and correlations indicated an anterior-posterior tilt of the baseplate occurred under loading (r² = 0.178-0.226, P = .009-.023).DiscussionFrom supine to standing position the predominant pattern of displacement for this cementless tibial baseplate was axial rotation, with some subjects also displaying an anterior-posterior tilt.     

颈椎弓根螺钉置入固定治疗颈椎不稳的疗效和安全性分析

目的分析颈椎弓根螺钉置入固定治疗颈椎不稳的临床结果，总结其临床疗效和安全性。方法颈椎弓根螺钉固定治疗颈椎不稳19例，平均随访时间为16．3个月。分析术前及术后6个月随访时JOA评分，采用颈椎残障功能量表（neck disability index，NDI）评价患者日常生活障碍程度变化。测量术后6个月及末次随访时颈椎屈伸侧位X线片，观察融合节段的稳定性。结果术后6个月随访时JOA评分较术前增加4．2±1．3（P〈0．05），平均改善率为61％。NDI评分术前为34．2±11．4，术后6个月为18．8±9．5（P〈0．01），随访时融合节段稳定。椎弓根螺钉骨皮质穿破率为7．6％，未出现神经、血管损伤。结论术前仔细研究影像学资料，颈椎弓根螺钉置入固定治疗颈椎不稳可以获得满意的临床疗效和安全性。     

Migration and clinical outcome of mobile-bearing versus fixed-bearing single-radius total knee arthroplasty

Background and purpose — Mobile-bearing total knee prostheses (TKPs) were developed in the 1970s in an attempt to increase function and improve implant longevity. However, modern fixed-bearing designs like the single-radius TKP may provide similar advantages. We compared tibial component migration measured with radiostereometric analysis (RSA) and clinical outcome of otherwise similarly designed cemented fixed-bearing and mobile-bearing single-radius TKPs.

Patients and methods — RSA measurements and clinical scores were assessed in 46 randomized patients at baseline, 6 months, 1 year, and annually thereafter up to 6 years postoperatively. A linear mixed-effects model was used to analyze the repeated measurements.

Results — Both groups showed comparable migration (p = 0.3), with a mean migration at 6-year follow-up of 0.90?mm (95% CI 0.49–1.41) for the fixed-bearing group compared with 1.22?mm (95% CI 0.75–1.80) for the mobile-bearing group. Clinical outcomes were similar between groups. 1 fixed-bearing knee was revised for aseptic loosening after 6 years and 2 knees (1 in each group) were revised for late infection. 2 knees (1 in each group) were suspected for loosening due to excessive migration. Another mobile-bearing knee was revised after an insert dislocation due to failure of the locking mechanism 6 weeks postoperatively, after which study inclusion was preliminary terminated.

Interpretation — Fixed-bearing and mobile-bearing single-radius TKPs showed similar migration. The latter may, however, expose patients to more complex surgical techniques and risks such as insert dislocations inherent to this rotating-platform design.     

Tibiofemoral Relationship 3 Weeks After Anatomic Triple-Bundle Anterior Cruciate Ligament Reconstruction With 10 N of Initial Tension Is Closer to Normal Knee Versus That With 20 N of Initial Tension

PurposeThis study aimed to clarify the effect of initial graft tension on the ensuing tibiofemoral relationship and on 2-year clinical outcomes after anatomic triple-bundle anterior cruciate ligament (ACL) reconstruction.MethodsA total of 31 patients with primary unilateral ACL rupture (mean age, 25.1 years) were enrolled. Anatomic triple-bundle ACL reconstruction was performed using semitendinosus tendon autografts, and patients were grouped according to the total initial tension at graft fixation: 20 N for 16 patients between January 2012 and December 2012 and 10 N for 15 patients between January 2013 and December 2013. Three-dimensional computed tomography scans were performed preoperatively and at 3 weeks and 6 months postoperatively. The side-to-side difference of the 3-dimensional tibial position relative to the femur was compared at each time point. The side-to-side difference in anterior laxity was sequentially compared preoperatively, immediately after surgery, and at 6 months and 2 years postoperatively. Clinical outcomes at 2 years were likewise compared.ResultsOne patient in each group was excluded because of secondary ACL injury. At 3 weeks postoperatively, 2.5 ± 1.3 and 1.0 ± 1.3 mm of posterior tibial displacement and 3.8° ± 2.4° and 2.0° ± 1.7° of external rotation were observed in the 20- and 10-N initial tension groups, respectively, with significant differences (P = .006 and .033). At 6 months postoperatively, anterior displacement was 0.1/0.1 mm and external rotation was 0.8°/0.4° in both groups, without any significant differences. The 2-year clinical outcomes were satisfactory, including mean side-to-side difference in anterior knee laxity of 0.5 mm in both groups.ConclusionThe tibiofemoral relationship 3 weeks after anatomic triple-bundle ACL reconstruction with 10 N of initial tension is less constrained than that with 20 N. Six-month tibiofemoral relationship and 2-year clinical outcomes are satisfactory in both groups.Level of EvidenceIII, retrospective comparative trial     

A randomized prospective study comparing migration of hydroxyapatite and non-hydroxyapatite coated glenoid components using radiostereometric analysis

BackgroundPrimary shoulder arthroplasty can significantly improve quality of life; however, the glenoid baseplate remains the most common component to loosen, which may result in implant failure and subsequent revision surgery. Radiostereometric analysis (RSA) is considered the gold standard for accurate measurement of micro-motion between implant and bone. The aims of this study were to compare migration of the Lima SMR porous titanium hydroxyapatite (HA) coated and non-hydroxyapatite (non-HA) coated glenoid components through a prospective, randomized 2-arm trial using RSA, whilst also comparing clinical and functional outcomes.MethodsTwenty patients were randomized into 2 equal (HA and non-HA coated) groups with all patients undergoing primary anatomic shoulder arthroplasty, at which time tantalum beads were also inserted. RSA imaging was performed immediately postoperatively, then at 3, 6, 12, and 24 months postprocedure. These images were digitized and analyzed using model-based RSA software. All patients completed Oxford Shoulder Score (OSS), American Shoulder and Elbow Surgeons (ASES) score, Constant Score (CS) and Visual Analogue Scale (VAS) pain scores pre-and postoperatively at the aforementioned time points. Unpaired t-tests were used for clinical outcome data; Mann-Whitney U tests were used for RSA data. Significance levels were set at P < .05.ResultsMean age for the HA group was 72.3 years; 69.5 years for the non-HA group. Mean follow-up for both groups was above 36 months. No significant differences in glenoid migration were observed at each of the postoperative time points; the only exception being at 12 months (non-HA group displaying significantly greater rotation in the z-axis). The HA group displayed fractionally more translation in the x- and z-axes at all time points (not significant). Rotation in the z-axis was marginally greater at all postoperative time points in the non-HA group. Median total migration values revealed greater motion for the non-HA group at 3, 6, and 12 months (not significant). All clinical outcome measures improved significantly within each group; no statistical differences were observed between the groups for any outcome measure. One patient in each group underwent revision surgery to reverse shoulder arthroplasty due to unexplained pain (HA group) and cuff failure (non-HA group) only. Radiolucent lines were noted in 2 patients who are still under follow-up.ConclusionThis study has revealed promising early results of both HA coated and non-HA coated implants, however, hydroxyapatite coating of glenoid components does not significantly improve outcome scores nor provide extra stability compared to non-hydroxyapatite coated implants at 2 years postprocedure.Level of evidenceLevel II; Randomized Controlled Trial     

Increased bone turnover as reflected by biochemical markers in patients with potentially unstable fixation of the tibial component

Introduction Whether biochemical markers of bone metabolism can be used in assessing the conditions of implant fixation is unknown. In this study, the serum levels of three bone markers were measured prospectively in patients undergoing total knee arthroplasty (TKA) to determine if patients with different fixation conditions of the tibial component showed any differences in the levels of the markers.Materials and methods The fixation of the tibial component in 40 knees (40 patients, 14 male and 26 female, average age 71 years) was assessed by radiostereometric analysis (RSA), and based upon the pattern of migration, implants with stable fixation (n=25) and potentially unstable fixation (n=15) were identified. Serum levels of carboxyterminal propeptide of type I procollagen (PICP), osteocalcin (OC) and cross-linked carboxyterminal telopeptide of type I collagen (ICTP) were assessed and compared between the two fixation groups. Blood samples were obtained preoperatively (baseline) and repeated postoperatively at 1 week, 3, 6, 12, and 24 months.Results The baseline levels of the markers were statistically the same (p>0.05) between the two fixation groups. Postoperatively, ICTP levels in the unstable group were significantly higher than in the stable group from 6 to 24 months (p=0.02). Levels of OC in the unstable group were higher at 12 and 24 months compared with the stable group, reaching statistical significance only at 12 months (p=0.03). No difference in the levels of PICP was found between the two groups.Conclusion The findings indicate a more active bone turnover probably at the bone-cement/implant interface in knees with potentially unstable fixation. It reveals the potential value for biochemical markers in monitoring implant fixation and aseptic loosening and suggests a possibility for improving implant fixation by drugs which inhibit osteolysis.     

Mobile- vs. fixed-bearing total knee replacement

Background and purpose — It is unclear whether mobile-bearing (MB) total knee arthroplasties reduce the risk of tibial component loosening compared to fixed-bearing (FB) designs. This randomized study investigated implant migration, periprosthetic bone mineral density (BMD), and patient-reported outcomes (Oxford knee score)—all at 2 years—for the P.F.C. Sigma Cruciate Retaining total knee arthroplasty.

Patients and methods — 50 osteoarthritis patients were allocated to either FB or MB tibial articulation.

Resultsand interpretation — At 2 years, the mean total translation (implant migration) was higher for the FB implant (0.30 mm, SD 0.22) than for the MB implant (0.17 mm, SD 0.09) (p = 0.04). BMD decreased between baseline and 1-year follow-up. At 2-year follow-up, BMD was close to the baseline level. The knee scores of both groups improved equally well. The FB tibial implant migrated more than the MB, but this was not clinically significant. The mobile polyethylene presumably partly absorbs the force transmitted to the metal tibial tray, thereby reducing micromotion.     

Reoperation rate and implant survivorship compared between cementless and cemented bipolar hemiarthroplasty in femoral neck fracture patients with chronic kidney disease

BackgroundChronic kidney disease (CKD) is commonly associated with aging and disorders of mineral and bone metabolism. Femoral neck fracture (FNF) is one of the most common fractures among older adults with coexisting CKD, and bipolar hemiarthroplasty (BHA) is a preferred treatment. However, the optimal method of stem fixation has not been conclusively determined. Accordingly, this study aimed to investigate the reoperation rate and implant survivorship compared between cementless and cemented BHA in FNF patients with CKD.MethodsA total of 183 FNF patients with moderate to severe CKD who underwent BHA during 2003 to 2019 were recruited and divided into either the cemented (CT group, n = 56) or cementless (CL group, 127) groups. Demographic data, preoperative laboratory investigations, preoperative radiographic outcomes, perioperative outcomes, and 90-day morbidity, mortality, and reoperation rates for any reason were recorded and compared between groups. Kaplan-Meier survival analysis was used to compare implant survivorship between the CT and CL groups. Cox proportional hazards regression model was used to identify independent risk factors for implant survivorship.ResultsThere were no significant differences in patient characteristics or preoperative data between groups, except for Dorr's classification of proximal femoral geometry. The CT group had a significantly lower proportion of Dorr type A (p = 0.020), and a higher proportion of Dorr type C (p<0.001). The CT group also had significantly more intraoperative blood loss (p<0.01). No significant differences in morbidity or mortality were observed. The median follow-up time in the CT group and CL group was 22.6 months (range: 0–151) and 22.6 months (range 0–154), respectively (p = 0.607). The reoperation rate was 5.4% and 4.7% among CT and CL patients, respectively (p = 1.000). There was no significant difference in the mean survival time between the CT (139.5 ± 6.3 months, 95%CI: 127.1–151.8) and CL (142.5 ± 4.7 months, 95%CI: 133.2–151.7) groups (p = 0.880). Univariate and multivariate analyses revealed no independent risk factors for implant survivorship.ConclusionThe results of this study showed no significant differences in the reoperation rate or implant survivorship between cemented and cementless BHA for treating FNF in moderate to severe CKD patients. A well-designed larger and longer-term study is needed to confirm these results.     

Monoblock versus modular polyethylene insert in uncemented total knee arthroplasty

Background and purpose — Backside wear of the polyethylene insert in total knee arthroplasty (TKA) can produce clinically significant levels of polyethylene debris, which can lead to loosening of the tibial component. Loosening due to polyethylene debris could theoretically be reduced in tibial components of monoblock polyethylene design, as there is no backside wear. We investigated the effect of 2 different tibial component designs, monoblock and modular polyethylene, on migration of the tibial component in uncemented TKA.

Patients and methods — In this randomized study, 53 patients (mean age 61 years), 32 in the monoblock group and 33 in the modular group, were followed for 2 years. Radiostereometric analysis (RSA) was done postoperatively after weight bearing and after 3, 6, 12, and 24 months. The primary endpoint of the study was comparison of the tibial component migration (expressed as maximum total point motion (MTPM)) of the 2 different implant designs.

Results — We did not find any statistically significant difference in MTPM between the groups at 3 months (p = 0.2) or at 6 months (p = 0.1), but at 12 and 24 months of follow-up there was a significant difference in MTPM of 0.36?mm (p = 0.02) and 0.42?mm (p = 0.02) between groups, with the highest amount of migration (1.0?mm) in the modular group. The difference in continuous migration (MTPM from 12 and 24 months) between the groups was 0.096?mm (p = 0.5), and when comparing MTPM from 3–24 months, the difference between the groups was 0.23?mm (p = 0.07).

Interpretation — In both study groups, we found the early migration pattern expected, with a relatively high initial amount of migration from operation to 3 months of follow-up, followed by stabilization of the implant with little migration thereafter. However, the modular implants had a statistically significantly higher degree of migration compared to the monoblock. We believe that the greater stiffness of the modular implants was the main reason for the difference in migration, but an initial creep in the polyethylene metal-back locking mechanism of the modular group could also be a possible explanation for the observed difference in migration between the 2 study groups.     

Contact Kinematics Correlates to Tibial Component Migration Following Single Radius Posterior Stabilized Knee Replacement

Background

Contact kinematics between total knee arthroplasty components is thought to affect implant migration; however, the interaction between kinematics and tibial component migration has not been thoroughly examined in a modern implant system.

A Biomechanical Comparison of the Effect of Baseplate Design and Bone Marrow Fat Infiltration on Tibial Baseplate Pullout Strength

BackgroundEarly clinical results of a new total knee arthroplasty (TKA) implant design show promise for improved outcomes and patellofemoral function scores. However, reports of early tibial component-cement interface debonding requiring revision have been published. This study investigated the biomechanical properties of three different tibial baseplates to understand potential causes of failure.MethodsPFC Sigma (control), Attune (1st generation) and Attune S+ (2nd generation) tibial baseplates were implanted into 4th generation sawbone tibia models using a standardized technique. Three of each baseplate were cemented with and without additional bovine bone marrow fat. All models were tested to failure with measured axial distraction force. Implant type, presence or absence of bovine marrow and load to failure were all recorded and compared. Two-way ANOVA followed by post-hoc pairwise comparisons were used to determine statistical significance, which was set to P < .05.ResultsThe 2nd generation tibial baseplates required significantly more force to failure. The presence of bovine marrow significantly reduced the pullout force of the implant designs overall. No significant difference was detected between the 1st generation and control baseplates. Failure mode for each model was also noted to be different irrespective of the presence or absence of bone marrow fat.ConclusionThe 2nd generation baseplates required significantly more force to failure compared with older designs. The presence of bone marrow during cementation of a tibial base plate significantly decreased axial pullout strength of a tibial baseplate in this laboratory model. All 1st generation baseplates exhibited debonding at the cement-implant interface.     

Valgus Subsidence of the Tibial Component Caused by Tibial Component Malpositioning in Cementless Oxford Mobile-Bearing Unicompartmental Knee Arthroplasty

BackgroundValgus subsidence (VS) of the tibial component is a rare complication of unicompartmental knee arthroplasty (UKA), and surgeons might consider revision surgery. The present study aimed to identify the factors related to VS of the tibial component after cementless Oxford mobile-bearing UKA.MethodsThe study included 120 patients who underwent Oxford mobile-bearing UKA using a cementless tibial component in our center between September 2015 and September 2016. Six showed VS of >2° after surgery. Patients were stratified into 2 groups according to the occurrence of VS of the tibial component (VS group, n = 6; no-subsidence group, n = 114). Postoperative radiographic evaluations were conducted to assess the varus/valgus alignment, rotation, and mediolateral position of the tibial and femoral components. The Oxford Knee Score (OKS) was assessed at 3, 6, and 12 months postoperatively. Positional parameters and sequential change in OKS were compared between the two groups using unpaired t-test (P < .05, statistically significant).ResultsAt 3 months postoperatively, an average VS of 3.4° in the VS group was observed, with a significant decrease in OKS. VS was associated with a significantly more medial position and external rotation of the tibial component. After 3 months, VS stopped, and the OKS gradually improved without revision surgery.ConclusionsVS might be caused by the malpositioning of the tibial component. VS of the tibial component after UKA appears to stop, with simultaneous pain relief, even without revision after 3 months postoperatively.     

Accuracy of patient-specific instrumentation in total ankle arthroplasty: A comparative study

BackgroundPatient-specific instrumentation (PSI) for TAA is a novel technology with several potential benefits. The primary goal of this study was to compare the use of PSI with the standard referencing guide (SRG) in regards to accuracy of tibial implant positioning. Operative time, fluoroscopy time and accuracy of PSI preoperative reports were also evaluated.MethodsA retrospective analysis of 99 patients who underwent a primary TAA with the INFINITY prosthesis (Wright Medical, Memphis, TN) was performed. Patients were divided in two groups based on the type of instrumentation used during the TAA (75 in the PSI group vs 24 in the SRG group). There was no significant difference between groups in regards to age at the time of surgery (P = 0.122), sex (P = 0.138), number of concomitant procedures performed during surgery (P = 0.567) and etiology (P = 0.841). However, preoperative deformity was significantly smaller in the PSI group (P = 0.002).ResultsTibial implant positioning was similar between groups. In the coronal plane, the absolute deviation of the tibial implant from the intended alignment was 1.7 ± 1.4° for the SRG and 1.6 ± 1.2° for PSI (P = 0.710). In the sagittal plane, the absolute alignment deviation of the tibial implant was 1.8 ± 1.4° for the SRG and 1.9 ± 1.5° for PSI (P = 0.675). Operative time (167 vs 190 min, P = 0.040) and fluoroscopy time (85 vs 158 s, P < 0.001) were significantly decreased in the PSI group. The PSI preoperative plan report correctly predicted the implant size in 73% of cases for the tibial component and in 51% of cases for the talar component.ConclusionsPSI provided similar tibial component alignment as standard instrumentation. Additionally, PSI preoperative plan reports were poor predictors of implant sizing. Therefore, the final decision should always be based on surgeon’s experience in order to prevent errors in implant sizing and positioning.Level of evidenceLevel III, retrospective comparative study.     

Early versus delayed weight bearing after intramedullary nailing for tibial shaft fracture: A multicenter,propensity score-matched study,the TRON study

ObjectivesThe purpose of this multicenter study was to assess the differences in the rates of implant failure and bone union by X-ray examination, and walking ability between an early weight-bearing group (EWB) and a non-weight-bearing group (NWB) following treatment with intramedullary nailing (IMN) for tibial shaft fractures with a propensity score-matching method.Material and MethodsWe collected data from 336 patients with tibia fractures that were treated surgically. We excluded patients lost to follow-up and polytrauma patients. Finally, 263 patients were included who were divided into two groups, the early weight-bearing (EWB) group, in which partial weight-bearing walking within four weeks was encouraged, and a non-weight-bearing (NWB) group, in which no weight bearing was allowed for more than four weeks. To adjust for baseline differences between groups, a propensity score algorithm was used to match the EWB group with the NWB group in a 1:1 ratio of 75 cases each. After matching, we compared the rate of implant failure, the rate of bone union at six months and one year after surgery, and walking ability at the last follow-up between the two groups.ResultImplant failure occurred in 0 of 75 patients in the EWB group vs. 1 of 75 in the NWB group (P = 1.0). Delayed bone union at six months occurred in 20 of 75 (26%) vs. 13 of 75 (17%) patients, and that at one year occurred in 5 of 75 (6.7%) vs. 3 of 75 (4%) patients. The median New Mobility Score was 9 (4–9) vs. 9 (0–9) points.ConclusionsThere were no statistically significant differences in the rate of implant failure, the rates of the bone union at six months and one year after surgery, and walking ability between the EWB group and NWB group. We suggest that instruction in early weight-bearing after IMN nailing for tibial shaft fracture may not be harmful.