Prosthesis Stem Research Articles

Reverse shoulder arthroplasty and synthetic mesh for reconstruction of the shoulder joint after malignant bone tumor resection

Abstract Introduction: A wide resection of malignant tumor including the deltoid insertion in the proximal humerus significantly worsens shoulder function. There are several reports about the reconstruction of the shoulder joint using reverse shoulder arthroplasty (RSA) after tumor resection. However, there have been no reports of reconstruction using RSA and a polypropylene mesh in combination with the modified L’Episcopo procedure. Patient concerns: An 83-year-old man complained of pain in his right shoulder. Diagnosis: The patient was diagnosed with dedifferentiated chondrosarcoma in the proximal humerus based on pathological assessment. Interventions: We excised the tumor with the proximal humerus including the deltoid attachment and reconstructed it with deltoid muscle by suturing it to polypropylene mesh covering the implant stem. We then performed a tendon transfer with the latissimus dorsi and teres major muscles in place of dissected posterior rotator cuffs as a modified L’Episcopo procedure. Outcomes: The pathological diagnosis confirmed a negative margin. His shoulder function improved at the 1-year follow-up. Conclusion: Reconstruction of the deltoid insertion using a polypropylene mesh surrounding the stem of an internal prosthesis during RSA is an easy technique and achieves relatively favorable shoulder function.

A comparison of short-stem prostheses and conventional stem prostheses in primary total hip arthroplasty: a systematic review and meta-analysis of randomized controlled trials.

BackgroundIn total hip arthroplasty (THA), short-stem prostheses (SS) were designed to achieve better preservation of proximal femoral bone stock and stability than conventional stem prostheses (CS), however these effects are controversial. We aimed perform a systematic review and meta-analysis to evaluate the effectiveness of SS and CS in primary THA.MethodsRelevant randomized controlled trials (RCTs) involving the comparison of SS and CS in primary THA were screened using the electronic databases PubMed, Embase and Web of Science. Data were analyzed with the RevMan 5.3 software program and evaluated with mean difference (MD), risk ratio (RR) and 95% confidence intervals (CIs) by random or fixed-effect models.ResultsSixteen RCTs involving 1,233 patients (1,486 hips) were included. Compared with CS, the incidence of thigh pain was significantly reduced with Proxima SS (RR 0.13, 95% CI, 0.03–0.51; P=0.004). Bone mineral density (BMD) with femoral neck-preserved SS [SS (I)] showed less decrease in Gruen zone 1 (MD 14.60, 95% CI, 10.67–18.54; P<0.00001) and Gruen zone 7 (MD 9.72, 95% CI, 5.21–14.23; P<0.0001) than CS. However, the changes of BMD were not significantly different between the SS without femoral neck preservation group [SS (II)] and the CS group. In addition, no significant differences were found in the revision rate, Harris Hip Score (HHS), or maximum total point motion (MTPM) between the SS and CS groups.ConclusionsThe results of this study showed that compared with CS, Proxima SS decreased the incidence of thigh pain and that SS (I) provided better proximal bone remodeling than CS. But the revision rates, HHS, and MTPM between SS and CS were similar. However, the findings of this meta-analysis require further verification in high-quality RCTs.

Onlay versus inlay reverse total shoulder arthroplasty: a retrospective comparison of radiographic and clinical outcomes

IntroductionRecent innovations in reverse shoulder arthroplasty (RSA) have presented 2 distinct humeral stem designs: an onlay system that rests above the anatomic neck and an inlay component that rests within the metaphysis. The purpose of this study is to compare clinical and radiographic outcomes between inlay and onlay-designed humeral stems in lateral center of rotation RSA implant systems. MethodsA retrospective cohort study was performed on primary RSA patients treated by 2 surgeons at 2 separate hospitals with a minimum 2-year follow-up. Patients were categorized based on treatment with an onlay or inlay humeral design and matched 1:1 by indication and age. Patient-reported outcome measures (PROMs), including the Simple Shoulder Test, American Shoulder and Elbow Surgeons, and Visual Analog Score for pain, as well as active motion (forward elevation, internal rotation) were recorded at pre- and postoperative intervals. An Inlay-Onlay index assessed the degree of inset or offset of each particular implant referencing the anatomic neck. Radiographic analysis focused on scapular notching, bone resorption around the humeral stem, and acromion stress fractures. ResultsA total of 92 patients participated in the 1:1 matched analysis (46 each group). Cohorts were similar in age, gender, indication, follow-up length, and preoperative PROMs, with the exception of Simple Shoulder Test. At the most recent follow-up, there were no differences in all PROMs between groups. There were no differences in active internal rotation, but patients with an onlay-configuration demonstrated greater external rotation (P< .001) and forward flexion (P< .001). Greater tuberosity and calcar resorption occurred in 34 (74%) and 18 (39%) patients with an onlay-designed prosthesis, compared to 13 (28%) and 1 (2%) in the inlay group, respectively (P< .0001). Both groups had low rates of scapular notching (P= 1.0), while acromial fractures occurred in 6 patients with an onlay stem and in 4 patients with the inlay stem (P= .73). ConclusionThere were no differences in clinical outcomes or incidence of acromial fractures following RSA with an onlay- or inlay-style humeral stem prosthesis. Bone resorption of the proximal humerus occurred more frequently in patients with an onlay prosthesis, suggesting that an inlay prosthesis may afford better prevention of humeral stress shielding. Level Of EvidenceLevel III; Retrospective Comparative Study

RESULTS OF MATHEMATICAL MODELING OF TENSION-DEFORMED CONDITION OF COMPONENTS OF KNEE JOINT ENDOPROSTHESIS IN CONDITIONS OF PRESENCE OF DEFECT EFFECTS

Summary. Gonarthrosis is reported in 50.6–54.5% of cases among patients with the lower extremities large joints’ dystrophic diseases. In 86% of cases, it affects people of working age, and in 6.5–14.6% - leads to disability. That is why, gonarthrosis is an acute medical and social problem. However, despite the large number of surgeries, the matter of choosing a method (bone plastic, metal insertion) to cover a bone bed’s defects for total knee arthroplasty (KJ) is still ambiguous. Objective: to conduct a computer simulation of strains occurring upon a regular and extended tibial stem of a knee prosthesis, depending on different tibial condylar defects. Materials and methods: the laboratory of biomechanics of the SI “ITO NAMS of Ukraine” created a computer model to study stress-deformed conditions of a KJ endoprosthesis upon a varus deformity of an extremity and knee arthroplasty with a regular and an extended tibial stem, if a bone defect has been replaced with a bone autograft of 5 and 10 mm. Results. It was determined that if a knee arthroplasty occurs upon conditions of a varus deformity, with an internal tibial condyle’s defect, the defect can be filled with an autograft insert up to 5 mm high, and a regular (short) prosthetic stem is suitable. If such a lesion is from 5 mm to 13.5 mm, an extended prosthetic stem is biomechanically justified. If a height of the defect exceeds 13.5 mm, it must be replaced with a massive metal insert. Practical essence: the study will be helpful to elaborate a differentiated approach to various tibial condyles’ defects treatment in the course of the total knee arthroplasty. Conclusions. The implementation of recommendations resulting from this study will increase the efficiency of treatment to this severe category of patients.

Postoperative Trends of Serum C-Reactive Protein Levels after Primary Shoulder Arthroplasty-Normal Trajectory and Influencing Factors.

Background—Postoperative serum C-reactive protein (CRP) is an important diagnostic parameter for systemic inflammation and reflects surgical trauma. While trends and normal trajectories after total knee (TKA) or hip arthroplasty (THA) are established, there is no reference standard for shoulder arthroplasty (SA). Therefore, the aim of this study was to research CRP trends and influencing factors following SA. Methods—This retrospective study analyzed postoperative serum CRP levels and trajectories in 280 patients following SA. Influence of prosthesis design, sex, operating time, BMI, and humeral augmentation with bone cement were analyzed using descriptive statistics and (non-) parametric testing. Results—There is a CRP trend with a peak on day two or three, with a subsequent decrease until day seven. Reverse and stemmed prostheses show a statistically higher CRP peak than stemless prostheses or hemiarthroplasties (HA). There was no influence of gender, body mass index (BMI), operating time, or bone cement. Conclusion—The presented findings may contribute to a better understanding of the postoperative CRP course after SA. The results of this retrospective study should be validated by a prospective study design in the future.

Biomechanical evaluation of the docking nail concept in periprosthetic fracture fixation around a stemmed total knee arthroplasty

Intramedullary femoral nails provide an ideal mechanical axis for periprosthetic fracture fixation. Slotted nails allow a connection to a total knee arthroplasty (TKA) stem. This study aims to compare implant and construct stiffness, interfragmentary movement and cycles to failure between an antegrade slotted femoral nail construct docked to a TKA stem and a distal femoral locking plate in a human periprosthetic femoral fracture model.In eight pairs of fresh-frozen human femora with stalked TKA, a 10 mm transverse osteotomy gap was set simulating a Rorabeck type II, Su type I fracture. The femora were pairwise instrumented with either an antegrade slotted nail coupled to the prosthesis stem, or a locking plate. Cyclic testing with a progressively increasing physiologic loading profile was performed at 2 Hz until catastrophic construct failure. Relative movement at the osteotomy site was monitored by means of optical motion tracking. In addition, four-point bending implant stiffness, torsional implant stiffness and frictional fit of the stem-nail connection were investigated via separate non-destructive tests.Intramedullary nails exhibited significantly higher four-point bending and significantly lower torsional implant stiffness than plates, P < 0.01. Increasing difference between nail and stem diameters decreased frictional fit at the stem-nail junction. Nail constructs provided significantly higher initial axial bending stiffness and cycles to failure (200 ± 83 N/mm; 16'871 ± 5'227) compared to plate constructs (93 ± 35 N/mm; 7'562 ± 1'064), P = 0.01. Relative axial translation at osteotomy level after 2'500 cycles was significantly smaller for nail fixation (0.14 ± 0.11 mm) compared with plate fixation (0.99 ± 0.20 mm), P < 0.01.From a biomechanical perspective, the docking nail concept offers higher initial and secondary stability under dynamic axial loading versus plating in TKA periprosthetic fracture fixation.

Improved functional outcome and tuberosity healing in patients treated with fracture stems than nonfracture stems during shoulder arthroplasty for proximal humeral fracture: a meta-analysis and systematic review

Proximal humeral fractures are difficult injuries to treat and obtain satisfactory outcomes. For those treated with arthroplasty, humeral fracture stems have been popular due to better ability for reduction and fixation of tuberosities. This study aims to investigate the outcomes of fracture stems in shoulder arthroplasty for proximal humeral fracture and the comparison of outcomes between fracture vs. nonfracture stems. A meta-analysis was conducted with a multidatabase search (PubMed, OVID, EMBASE, Medline) according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines on May 19, 2020. Data from all published literature meeting inclusion criteria were extracted and analyzed. Eleven studies were included for analysis, including 383 hemiarthroplasties (HA) (294 fracture stems, 89 nonfracture stems) and 358 reverse total shoulder arthroplasties (RTSA) (309 fracture stems, 49 nonfracture stems). At the final follow-up, meta-analysis shows favorable overall ASES score in all fracture stem prosthesis (mean = 74.0, 95% confidence interval [CI]: 69.3-78.7), Constant-Murley score (mean = 67.2, 95% CI: 61.6-72.8), external rotation (mean difference [MD] = 7°, 95% CI: 3°-10°, P < .001), and forward flexion (MD = 17°, 95% CI: 10°-25°, P < .001). Pooled proportion (PP) of greater tuberosity healing (PP = 0.786, 95% CI: 0.686-0.886) was high, whereas all-cause revisions (PP = 0.034, 95% CI: 0.018-0.061) remained low. With the exception of RTSA scapular notching (PP = 0.109, 95% CI: 0.020-0.343), other complication metrics had PP of ≤0.023. In the 4 studies comparing fracture (138 HA, 54 RTSA) vs. nonfracture stems (89 HA, 49 RTSA), fracture stems had statistically significant better American Shoulder and Elbow Surgeons scores (MD = 14.29, 95% CI: 8.18-20.41, P < .001), external rotation (MD = 6°, 95% CI: 2°-9°, P = .003), forward flexion (MD = 16°, 95% CI: 7°-24°, P < .001), and greater tuberosity healing (odds ratio = 2.20, 95% CI: 1.28-3.77, P = .004). There was no statistically significant difference in complications. Fracture stems showed promising overall clinical outcomes with low complication rates in treating proximal humeral fractures. The use of fracture stems is also associated with greater chance of tuberosity healing compared with nonfracture stems. There is increasing evidence to suggest the superiority of fracture stems over nonfracture stems in clinical outcomes, while maintaining similar complication rates.

A CT-based method to compute femur remodelling after total hip arthroplasty

ABSTRACT Bone remodelling after total hip arthroplasty has been largely observed and investigated. Most studies rely on projective images and only few obtain 3D information with limited spatial resolution. This study proposes a method to provide quantitative, 3D high-resolution data about femur bone density variations, by means of CT volume processing. This would offer a tool for further research and clinical studies. Five patients subjected to primary, cementless total hip arthroplasty were considered. Calibrated CT volumes were acquired before, just after surgery and 1 yr later. Bone remodelling hinders accurate alignment of femur volumes acquired after a year; instead, prosthesis stem remains unchanged. Thus, after metal artefact reduction, prosthesis was segmented, and stem-based accurate alignment was obtained. A test to exclude prosthesis migration was performed by considering specific femur anatomical landmarks. Bone density error due to artefact reduction and realignment was estimated. Quantitative differences in bone mineral density were computed for each voxel, providing a resolution of about 1 mm. Preliminary results showed that the femur underwent consistent remodelling after a year. Widespread bone density losses appeared in those areas where strain-adaptive remodelling is normally expected, particularly about the calcar. Conversely, distal areas with clear stem-bone contact showed considerable density gains.

Biomechanical evaluation of retrograde docking nailing to a total hip arthroplasty stem in a periprosthetic femur fracture model

IntroductionSlotted nails allow a connection to a total hip arthroplasty (THA) stem and act as intramedullary load carrier. This study compares construct stiffness, cycles to failure and failure load between a retrograde slotted femur nail construct docked to a THA stem and a lateral locking plate in a human periprosthetic femur fracture model. Materials and methodsIn seven pairs of fresh-frozen human anatomic femora with cemented THA, a transverse osteotomy was set simulating a Vancouver type B1 fracture. The femora were instrumented pairwise with either a retrograde slotted nail coupled to the prosthesis stem, or a locking plate plus a locking attachment plate. Four-point mediolateral bending, torsional and axial bending construct stiffness was investigated via non-destructive tests. Cyclic testing under progressively increasing physiologic loading was performed at 2 Hz until catastrophic construct failure. ResultsMediolateral bending stiffness did not differ significantly between the two groups (P=0.17) but exhibited a biphasic profile with significantly increased stiffness in both groups (P<0.01). Nail constructs provided a significantly lower torsional stiffness (0.49 ± 0.66 Nm/°) than plate constructs (1.70 ± 0.86 Nm/°), P=0.03. Axial bending stiffness did not differ significantly between the groups (Nail: 605 ± 511 N/mm; Plate: 381 ± 428 N/mm), P=0.61. Cycles to failure and failure load were significantly higher for the plate constructs (25’700 ± 8’341; 3’070 ± 1334 N) compared with the nail constructs (20’729 ± 7’949; 2’573 ± 1295 N), P=0.04. ConclusionThe docking nail construct provides an intramedullary fixation with connection to the prosthesis stem; however, it is biomechanically weaker in stable fractures compared to the plate construct.

Accuracy of Preoperative Templating in Total Hip Arthroplasty With Special Focus on Stem Morphology: A Randomized Comparison Between Common Digital and Three-Dimensional Planning Using Biplanar Radiographs

BackgroundAccurate preoperative planning is a key component of successful total hip arthroplasty (THA). The purpose of the present study was to compare the accuracy and reliability of three-dimensional (hipEOS) and common digital two-dimensional (TraumaCad) templating with special focus on stem morphology. Methods51 patients undergoing THA were randomized to two groups. Preoperative planning was performed on 23 patients with hipEOS (3D) and on 28 patients with TraumaCad (2D) planning software. Planning results were compared with the implanted component size. Inter- and intraobserver reliability as well as planning accuracy of both planning methods with special focus on straight and short stem design were recorded. ResultsIntraobserver reliability of both planning methods was good for component planning (ICC2,1: 0.835-0.967). Interobserver ICC2,1 for stem and cup planning were higher for 3D templating (3D ICC2,1: 0.906-0.918 vs. 2D ICC2,1: 0.835-0.843). Total stem and cup size predictions were within 2 sizes for 3D and within 3 sizes for 2D planning. Comparing short stem planning accuracy of both planning methods, absolute difference between implanted and planned component size was significantly lower in 3D planning (P = .029). There was no significant difference in straight stem (P = .935) and cup (P = .954) planning accuracy. ConclusionOur findings suggest that 3D templating with hipEOS software has a good overall reliability and may have a better planning accuracy of short stem prostheses than digital templating with TraumaCad software. Assuming that the number of implanted short stem prostheses will further increase in coming years, a more precise planning with 3D technique can contribute to improve surgery outcome.

The Sensitivity Analysis in Topology Optimization of Hip Stem Prosthesis Using Finite Element Method

This paper discusses the results of the parameters employed sensitivity analysis in the optimization of hip stem prosthesis geometry using topology optimization techniques based on finite element methods. The study was carried out to examine the relationship of finite element parameters, such as mesh size and stress distribution, and topology optimization parameters, such as percent to retain, to the final geometry of the prosthesis stem. Topology optimization was performed using ANSYS software for hip stem prosthesis, a type of Anatomic Medullary Locking, made from titanium alloy. The results obtained from this study indicate that the selection of finite element parameters and topology optimization parameters will have a significant effect on the shape and geometry of the hip stem. The results of this analysis can be the basis for the development of hip stem shape and geometry through topology optimization techniques.

Comparison of cylindrical and tapered stem designs for femoral revision hip arthroplasty

BackgroundBoth cylindrical and tapered stems are commonly used in revision total hip arthroplasty. However, whether the geometry of prosthesis stem has an effect on patient prognosis is unclear. We assume that the tapered stem results in better clinical outcome than the cylindrical stem.MethodsA multicenter review of 120 femoral revisions with Paprosky I, II, and III defects using cobalt chrome cylindrical stem (54 hips) or titanium tapered stem (66 hips) was performed with an average follow-up of 6 years. Demographic data were comparable between groups.ResultsNo significant group differences were found in surgery time, bleeding volume, postoperative Harris Hip Score, level of overall satisfaction, and 8-year cumulative survival. However, intraoperative fractures occurred significantly less in the tapered group (4.5%) than in the cylindrical group (14.8%), and stem subsidence was significantly less in the tapered group (2.17 mm) than in the cylindrical group (4.17 mm). A higher ratio of bone repair and lower bone loss were observed in the tapered group compared with the cylindrical group. The postoperative thigh pain rate was higher in the cylindrical group (12.9%) than in the tapered group (4.5%).ConclusionBoth cylindrical stem and tapered stem can achieve satisfactory mid-term clinical results in revision total hip arthroplasty. The tapered stem has better bone restoration of proximal femur, lower incidence of intraoperative fractures, and lower postoperative thigh pain rate compared with the cylindrical stem.

Is diaphyseal fixation of short neck-retaining stem prostheses related to the size of the implant?

Short-stem hip prostheses present variable proximal femoral bone radiological findings. The aims of this study were to analyse, in our patients with implanted collum femoris-preserving (CFP) stems, cancellous bone remodelling, cortical distal hypertrophy and pedestal formation, and the relationship between those radiological changes that suggest distal fixation with the size of the stem. From October 2001 to December 2012 a total of 199 consecutive primary total hip arthroplasties in 180 patients were performed at our department using the CFP stem and followed up for a minimum of 5 years until December 2017. Stress shielding was present in 74% of oversized stems cases, but in normal or undersized stems, stress shielding was present in 8.5%. Cortical hyperthrophy was observed in 49% of the oversized stems and in 6% of the normal or undersized ones. Finally, non-statistically significant differences (p = 0.089) in pedestal formation were found, present in 16.3% of the oversized stems and in 6% of normal or undersized ones. Oversized stems cause more stress shielding and distal cortical hypertrophy in the distal part of the stem, which indicates distal fixation in bigger sizes of stem.

Short stems for total hip replacement among middle-aged patients.

The purpose of the present study was to investigate the role of short stem implants for primary total hip arthroplasty in middle-aged patients. For this purpose,a meta-analysisof the current literature was conducted. The focus was onclinical outcomes,radiological parameters, and further complications of both components. The studywas performed according to the PRISMA guidelines.All randomized and non-randomized clinical trials comparing short stem versus standard stem prosthesesfor THA were considered for inclusion. Only studies reporting data concerning uncemented stems for primary total hip arthroplasty were included. Only studies reporting data concerning patients with a mean age of 45 to 69 were included. A total of 2197 procedures in 2116 patients were analysed. The mean follow-up was 30.2months. The short stem group showed a statistically significant higher WOMAC score and a reduced total estimated blood loss compared with the standard stem group. The short stem group showed a reduced rate of femoral fractures, dislocations, and revision, but without statistical significance. According to the main findings of this meta-analysis and current evidence, we encourage the use of the uncemented short stems during primary total hip arthroplasty in middle-aged patients.

Evaluation of Heat Transfer on Bone Cemented Hip Replacement

Evaluation of observable response of heat of bone cement in hip replacement was studied. In an exothermic reaction, bone cementing in a polymerization reaction between the liquid and the powder monomer, provides the bonding mechanism between the prosthesis stem and the femur cavity. This is of concern to biomechanics engineers on the mechanism of heat transfer between the femur bone, the cement and the prosthesis stem. The ANSYS software together with Autodesk software was used to model the scenario, steady state thermal structural analysis was used to simulate it. From the observation, the PMMA polymer (used as bone cement) temperature from the exothermic reaction raised the temperature in the assembly thereby creating a flow of heat amounting to 5.11x10-7W/m2 in which only 2.83x10-7 W/m2reached to the femur bone as others has been absorbed by the femur bone and prosthesis stem.0.59kJ/kg.K and 1.297kJ/kg. Kare the values of specific heat capacities of femur bone and PMMA respectively while the values of young modulus for femur bone and PMMA are 18.79GPa and 28.78GPa respectively. This result shows how possible it is to determine these properties from the studies of simulation.

Outcome of short- to medium-term migration analysis of a cementless short stem total hip arthroplasty using EBRA-FCA: a radiological and clinical study.

Stress shielding may lead to aseptic loosening which is a common reason for implant failure. An established method to identify implants with risk of implant failure caused by aseptic loosening is to measure early migration of the stem with the "Ein Bild Roentgen Analyse" femoral component analysis (EBRA-FCA). Therefore, the aim of this study was to measure the migration of a cementless short stem prosthesis via EBRA-FCA to predict the future performance. A total collective of 71 patients were treated with a cementless short hip stem prosthesis. Indications for surgery were primary coxarthrosis, dysplasia coxarthrosis or femoral head necrosis. After surgery, the patients were followed-up immediately after 3, 6, 12, 24, 36, and 48months and X-ray images for EBRA-FCA measurements were taken. Axial caudal migration as well as the varus/valgus tilting of the prosthesis was determined. Possible influencing factors like BMI, age, diagnosis, gender or Harris Hip Score (HHS) on the migration of the stem were assessed. HHS increased significantly direct postoperatively (p < 0.001). At the second follow-up the average caudal migration was 0.42 ± 0.52mm (range: 0.00-2.85mm) (p < 0.001). A total of 14 patients underwent a caudal migration greater than 1.5mm until 48months. The initial varus and valgus tilts within the first 3months were significant (p < 0.001). No correlations between BMI, age, diagnosis, gender or HHS and the migration as well as the tilting of the cementless short hip stem prosthesis were found. Although initial axial caudal migration as well as tilting tendencies in varus or valgus position can be detected, there is no marked migration of the examined prosthesis after the first 48months. Likewise, no aseptic early loosening was detected throughout the study period, which indicates good osseointegration of the short stem prosthesis.

Complication inhabituelle à 20 ans d’une arthroplastie trapézo-métacarpienne

Trapeziometacarpal joint arthroplasty is a reliable method for treating TM osteoarthritis, with the major benefit of rapid pain relief and recovery after surgery. Despite recent advances in prosthetic design, with a 90% survival rate at 10 years, there remain complication risks that cannot be ignored. The most common complications are prosthetic dislocation and trapezial cup loosening. To our knowledge, flexor tendon rupture has not been reported after TM joint arthroplasty. We report a unique case of total asymptomatic trapeziometacarpal prosthesis dislocation, accidentally discovered after the occurrence of a rupture of the index flexor tendons more than 20 years after surgery in an 82-year-old woman. Formal testing was informative and confirmed the lack of normal function of the superficial and profundus flexor tendons of her left index finger. There was no sign of carpal tunnel compression. She showed satisfactory thumb mobility with a Kapandji score of 8/10 and a grip strength of 10 kg. She had near-comparable mobility to the contralateral healthy side. X-rays showed a total dislocation of the prosthesis stem, whose proximal end was located next to the carpal tunnel. We undertook surgical exploration via a carpal tunnel approach. The prosthesis stem was located at the radial base of the carpal tunnel. Both index flexor tendons were ruptured. The stem was removed and not replaced. The reconstruction of the index profundus flexor tendon was performed by transfer of the ring finger flexor superficialis tendon using the Pulvertaft technique in zone 3. Immobilization was considered unnecessary. Active and passive rehabilitation were performed daily and initiated on postoperative day 1. Follow-up at 6 months showed satisfactory motion of the thumb without any pain, a Kapandji score of 8/10, a grip strength of 12 kg, satisfactory flexion of the index and ring fingers, and a Quick-DASH score of 29.55/100. We noticed a clinical shortening of the thumb explained by significant shortening of M1 on radiographs. This case presents a rare case of complication of trapeziometacarpal joint arthroplasty, since dislocation went unnoticed for a considerable time. Our strategy was to avoid any loss of range of motion. Prosthesis removal was efficient and ring finger superficial flexor tendon transposition allowed immobilization to be avoided. This observation adds a new clinical complication of the trapeziometacarpal prosthesis, and shows an example of how it was promptly managed.

Total Hip Arthroplasty with Modular Stem for Dysplastic Hips in South Asian Population.

Optimum component positioning and orientation is required to optimize the functional result during total hip arthroplasty for dysplastic hips. Sixty-two patients (66 hips) including 33 males and 29 females underwent total hip arthroplasty using modular stem prosthesis at an average age of 40.6 years (range 17 to 49 years). Nineteen hips were classified as Type I, 24 hips as Type II, 13 hips as Type III and 10 hips as Type IV dysplastic hips according to Crowe's classification. Eighteen hips (27.2%) underwent sub trochanteric osteotomy and 23 hips (34.8%) required adductor tenotomy at the time of surgery. Sixty-one patients (65 hips) were available for the latest follow up. The median follow-up was 57.4 months (range12 to 100 months). The mean Harris Hip Score was 90.6 (range 72 to 96), which was significant improvement from the preoperative Score of 44.8 (range 38 to 62). The clinical outcome was graded as excellent in 39, good in 13, fair in 7 patients and poor in 2 patients respectively. Only one hip (1.5%) had underwent revision surgery for the stem at 18 months following the index surgery. Postoperative dislocation following a fall was seen in one hip of a female patient who was operated on both sides. The radiographs revealed that all the remaining 65 hips had stable femoral component and the osteotomy sites were healed. The Kaplan-Meier survivorship with revision as endpoint (including open reduction for dislocation) was found to be 96.4% at 100 months (95% Confidence Interval; 86.3-99.1). This study in South-Asian patients using the modular stem strengthened the premise that cementless modular total hip arthroplasty provides a satisfactory outcome in treating secondary osteoarthritis due to dysplastic hips.

Cable plate fixation for Vancouver Type-B1 periprosthetic femoral fractures-Our experience and identification of a subset at risk of non-union

IntroductionManagement of periprosthetic femoral fractures is challenging. Vancouver classification is universally accepted for fracture description and management algorithm. Guidelines for the treatment of type B1 fracture is open reduction and internal fixation. The difficulty involved in managing this group is evidenced by the array of treatment options described in the literature. MethodsThirty two patients with Vancouver type B1 fracture treated with osteosynthesis using cable plate (between 2007 and 2015) were reviewed retrospectively. There were 21 females and 11 males with an average age of 81yrs (56–96 years). The average follow-up was 21 months. All patients were reviewed clinically and radiologically until fracture united or patient re-operated. Postoperative protocol followed was six weeks toe touch weight bearing, 6 weeks partial weight bearing and then full weight bearing if there was no displacement. Post-operative radiographs were evaluated for fracture union. Statistical analysis was done using contingency tables with Fishers exact test and a p-value < 0.05 for significance. ResultsIn twenty four patients fracture union was achieved. Non-union was recorded in four patients. Comparing the different fracture patterns all non-unions occurred in the fractures which were short oblique or transverse at the cemented stem tip (p = 0.001). Fractures were more common in female patients and associated more with the uncemented femoral stems, but it was not associated with increased rate of non-union (p = 0.68). All failed osteosynthesis were revised successfully using long stem prosthesis. Two patients died within 2 months, one patient died within 4 months, one patient was lost to follow-up. ConclusionTransverse or short oblique periprosthetic fractures around tip of cemented femoral stems can have high failure rates with just internal fixation. Revision arthroplasty may be the preferred option if possible otherwise may need to supplement fixation with cortical onlay graft. We should consider subcategorising Vancouver type B1 periprosthetic fractures into groups based on the pattern and fracture level in relation to the femoral stem.

Application of bone-retaining femoral stem prosthesis in young patients with Dorr C femoral medullary cavity

To assess the clinical efficacy of Tri-Lock bio-short prosthesis in artificial total hip arthroplasty(THA) in young patients with Dorr type C femoral medullary cavity. From January 2010 to January 2014, 35 young patients(37 hips) with in the chimney-like femoral medullary cavity received Tri-Lock BPS prosthesis of THA, including 18 males(20 hips) and 17 females with an average age of (32.2±3.0) years old ranging from 21.2 to 38.5 years old. There were 16 cases of rheumatoid hip arthritis (17 hips), 8 cases of rheumatoid arthritis (9 hips), and 11 cases of aseptic necrosis of femoral head (11 hips). All cases were complicated with different degrees of osteoporosis. According to Singh index, 26 cases were classified as Grade III and 9 cases as Grade II. Biological prostheses were used for the acetabulum, with ceramic lining and full ceramic femoral head. The proximal femoral medullary cavity was Dorr type C on anteroposterior X-ray. After replacement, X-ray examination was performed to locate the prosthesis stem. Engh and Harris criteria were used to evaluate the stability of bone-prosthesis interface and hip function, respectively. Changes of hip movement pre-operation and at last follow-up were compared. All patients were followed up for 18 to 45 months(means 33.8 months). Harris hip scores in 35 cases (37 hips) increased significantly from preoperative 61.8±3.0 (51.2 to 73.5) to 93.3±6.5 (92.5 to 98.8) points at last follow-up (t=54.745, P<0.01). The hip mobility increased from (46.5±8.0)°(0° to 55°) before surgery to(101.2±10.5)°(85° to 130°) at the last follow-up, the difference was statistically significant(t=133.091, P<0.01). Immediately after surgery, the prostheses were tightly packed with the medullary cavity. At the final follow-up, 17 hips had significant femur cortical bone thickening;12 hips had varying degrees of stress occlusal bone resorption at proximal femoral, including 9 degree I(low femur density, round and blunt) and 3 degree II(involving small rotor) hips. Meanwhile, 15 hips had significant femur cortical bone thickening without thigh pain. The cone-shaped short Tri-lock biological short-stem can fill Dorr C chimney-like medullary cavity and effectively retain good proximal femoral bone mass. Titanium microporous coating on the surface can effectively increase the friction of the prosthesis. The short-stem end in the medullary cavity can effectively avoid the occurrence of coxa varus.