Aim: This study was performed to review the early results of the use of a semi-constrained acetabular component in the treatment of recurrent hip dislocation at Palmerston North Hospital. Method: A retrospective case study of patients who underwent acetabular component revision with a semi-constrained cup for recurrent dislocation of the hip was performed. Results: Between April 1999 and July 2000, 10 patients with an average age of 75 years underwent acetabulum revision with a semi-constrained cup. There was an average of four dislocations before revision surgery, per patient. At follow-up between three and 18 months after the revision, there had been no dislocations. Aggressive post-operative rehabilitation was permitted, allowing discharge at an average of seven days postoperatively. Conclusion: The use of a semi-constrained acetabular cup was successful as a means of treatment for recurrent hip dislocation. This is an early review of the use of the implant. There are no published data on long term survival of this implant. The semi-constrained cup provides a simple yet effective option for dealing with the elderly recurrent hip dislocation

Introduction. The Flexible Nichidai Knee (FNK) System (Nakashima Medical, Japan) was designed to fit Asian knees. Especially, the posterior stabilized(PS) prosthesis was designed as semi-constrained posterior stabilized system that had a large tibial post and femoral articulation. We hypothesized that the semi-constrained PS implant design would have a positive influence on vivo kinematics after total knee arthroplasty (TKA). Materials and Methods. A total of 16 patients (21 knees) who had undergone TKA using PS implant were randomly recruited from our database. Of the 16 patients, all patients were women. Fourteen patients had osteoarthritis and 2 patients had rheumatoid arthritis. The average age was 72.3± 9.5 years, and the average postoperative duration was 23.4 ± 19.3 months. The subject performed sequential deep knee bends under WB from 0° to maximum flexion under fluoroscopic monitoring in the sagittal plane. Conversely, under NWB, the patient sat on a chair and was asked to perform active assisted knee flexion. To estimate spatial position and orientation of the artificial knee prosthesis, a 2D to 3D registration technique was used. We evaluated knee range of motion, femoral axial rotation relative to the tibial component, and anteroposterior translation of the femorotibial contact point for both medial and lateral sides. Closest distances between femoral cam and tibial post engagement were measured,. Results. Range of Motion. The mean full extension angle between femoral and tibial components, was −8.1±8.8°and −7.5±5.5°in WB and NWB, respectively. The mean maximum-flexion angle was 110.0±18.1°and 119.3±8.9°in WB and NWB, respectively. Femoral Axial Rotation. Fig.1 shows the mean degree of femoral axial rotation relative to the tibial components in WB and NWB. The femur was externally rotated 0.7±3.9°and 0.3±4.7°at 0° degree in WB and NWB, respectively. The external rotation increased to 4.8±5.2°and 6.2±5.9°at 120°flexion in WB and NWB, respectively. Anteroposterior Translation. The mean femorotibial contact point under WB and NWB was shown in Fig.2 for medial contact and Fig. 3 for lateral contact. Under WB, the mean medial contact point moved posteriorly from −1.6±2.0mm at 0° flexion. The point then moved gradually anteriorly with flexion to −9.3±1.5mm at 120°flexion. The mean lateral contact point moved posteriorly from −1.9±1.7mm at 0° flexion, and then moved anteriorly to at −8.9±2.7mm 120° flexion. Under NWB conditions, the mean medial contact point moved posteriorly from −1.1±1.8mm at 0° flexion. The point then moved gradually posteriorly with flexion to −6.6±2.8mm at 120° flexion. The mean lateral contact point in PS TKA moved posteriorly from −4.4±3.3mm at 0° flexion, and then moved posteriorly to −12.3±3.6mm at 120°flexion. Post-Cam Engagement. The mean knee flexion angle at initial post-cam engagement was 61.9 ± 15.9° under WB and 57.5 ± 16.0° under NWB. Discussion. Our study showed external rotation and bycondylar posterior rollback pattern in the entire range of knee flexion. The reason for this might be that the post cam design was high(20mm), which does not allow for high external rotation. The in vivo kinematics of the semi-constrained PS FNK prosthesis showed similar kinematic patterns due to the development concept of the implant design

To show the role and effectiveness of semi-constrained total elbow arthroplasty in restoring elbow function in severe, irreversible post-traumatic osseous and chondral injuries. Eighteen patients, aged 19–80, 11 male and 7 female, suffering from serious, irreversible anatomical and functional lesions of the elbow joint due to previous severe untreated or inadequately treated fractures (T-type transcondylar, trochlear-condylar, open fxs with large bony defects, severe osteochondral, heterotopic ossification in ICU fracture patients). Postop follow up was 9–57 months. All patients were treated with modular, cemented, semi-constrained linked total elbow arthroplasty. A functional brace was used post-operatively, and motion was permitted on the 3rd post-op day. The patients were allowed a full range of motion at 1 week post-op and they were subjected to vigorous physiotherapy. Post-op results were evaluated by using Mayo, DASH, quick-DASH scores and measuring grip strength and range of motion. Our results ranged from satisfactory to excellent in 16 patiens, with good strength and wide motion arc (with up to 15o extension-flexion deficit). One old female patient suffered a severe cerebral stroke with a bad outcome. In another young male patient the motion arc reached only 40% of the normal (spasticity, ICU patient with brain injury). Semi-constrained linked total elbow arthroplasty proves to be an effective method of treatment in severe, irreversible, intraarticular post-traumatic elbow injuries with chondral destruction and grave functional deficit, provided the proper technique is employed and a vigorous rehabilitation program is followed

Patient function is poorly characterised following revision TKA. Modern semi-constrained implants are suggested to offer high levels of function, however, data is lacking to justify this claim. 52 consecutive aseptic revision TKA procedures performed at a single centre were prospectively evaluated; all were revision of a primary implant to a Triathlon total stabiliser prosthesis. Patients were assessed pre-operatively and at 6, 26, 52 and 104 weeks post-op. Outcome assessments were the Oxford Knee Score (OKS), range of motion, pain rating scale and timed functional assessment battery. Analysis was by repeated measures ANOVA with post-hoc Tukey HSD 95% simultaneous confidence intervals as pairwise comparison. Secondary analysis compared the results of this revision cohort to previously reported primary TKA data, performed by the same surgeons, with identical outcome assessments at equivalent time points. Mean age was 73.23 (SD 10.41) years, 57% were male. Mean time since index surgery was 9.03 (SD 5.6) years. 3 patients were lost to follow-up. All outcome parameters improved significantly over time (p <0.001). Post-hoc analysis demonstrated that all outcomes changed between pre-op, 6 week and 26 weeks post-op assessments. No difference was seen between primary and revision cohorts in OKS (p = 0.2) or pain scores (p=0.19). Range of motion and functional performance was different between groups over the 2 year period (p=0.03), however this was due to differing pre-operative scores, post-hoc analysis showed no difference between groups at any post-operative time point. Patients undergoing aseptic revision TKA with semi-constrained implants made substantial improvements in OKS, pain scores, knee flexion, and timed functional performance, with the outcomes achieved comparable to those of primary TKA. High levels of function can be achieved following revision knee arthroplasty, which may be important considering the changing need for, and demographics of, revision surgery

Osteoarthritis of the trapeziometacarpal joint can be treated by different surgical procedures. These are known to lead to complications, complex regional pain syndrome (CRPS) type I being one of them. We investigated prospectively our clinical results after total joint arthroplasty under vitamin C prophylaxis. Patients with trapeziometacarpal joint arthritis stage II or III (according to Dell) underwent joint arthroplasty. Visual analogue scale (VAS) scores for pain, activities of daily living (ADL), satisfaction and first web opening were taken pre- and postoperatively. Vitamin C 500 mg daily was started two days prior to surgery during 50 days as prophylaxis for CRPS. Postoperative treatment consisted of a bandage with collar and cuff for 5 days. Follow-up was at 2 and 6 weeks, 6 months and 12 months (with check radiographs). We performed 34 arthroplasties in 29 patients (23 females and 6 males) with a mean follow-up of 39 months. Mean age was 61 years. The degree of osteoarthritis according to Dell was stage II in 13 cases, stage III 20 times and in one case there was a traumatic trapeziometacarpal dislocation. Operation was performed in day care under general or regional anesthesia. We implanted a hydroxy-apatite coated, semi-constrained prosthesis, type Roseland (total trapeziometacarpal joint prosthesis; Depuy International Ltd, Leeds, England). First web opening increased with 18 degrees and there was a significant improvement for pain, ADL and satisfaction as well (p = 0.000). There were no signs of loosening of the prosthesis, no infections and no cases of CRPS. In this study the postoperative treatment was completely functional. The semi-constrained design of the Roseland prosthesis doesn’t require immobilisation. Torrededia reported 5 patients with CRPS after 38 operations with this same implant (13%). The positive trend in preventing CRPS gives us enough arguments to further investigate this in the form of a RCT

Purpose: We report our experience with 23 Coonrad-Morrey total elbow prostheses. Material and methods: Between July 1997 and February 2001, we implanted 34 Coonrad-Morrey total elbow pros-theses in 33 patients. Twenty-three patients (23 implants) were reviewed at a mean 24 months follow-up, maximum 40 months. There were three men and 20 women, mean age 62 years (42–69). Twelve patients had rheumatoid polyarthritis, the principal indication. There were also four recent fractures of the distal humerus, two nonunions, and one patient with post-traumatic osteoarthritis. One patient had sequelar osteoarthritis since childhood. Finally three revisions were performed for loosening of a GUEPAR prosthesis in two cases and a GSBIII prosthesis in one. Results were assessed with the Mayo Clinic score. We searched for lucent lines around the implants, polyethylene wear, and incorporation of the bone graft behind the anterior wing of the implant on plain radiographs. Results: At last follow-up, the mean Mayo Clinic score had improved from 25 to 89 points (70–100). Before surgery, 17 patients had severe pain. At last follow-up, eight patients had occasional pain. Extension was improved by 10°, flexion by 27° giving a postoperative amplitude of 29° to 132°. Prona-tion supination progressed by 37° giving a rotation amplitude of 127°. The function score improved from 4 to 21 points. Sixteen of the 23 patients had normal elbow function. Outcome was excellent in 13 patients, good in eight, and fair in two. There were no lucent lines visible on the radiographs. There was no sign of polyethylene wear. The bon graft was incorporated behind the implant in 20 cases and was not visible in three. Complications included one peroperative fracture, one cutaneous dehiscence, one post-operative fracture of the olecranon due to a fall, and persistent ulnar paresthesia in four patients requiring secondary neurolysis in one. Discussion, conclusion: The Coonrad-Morrey semi-constrained prosthesis provides a response to a large range of situations. The dominant indication is rheumatoid polyarthritis, but trauma patients can benefit from this reliable therapeutic solution giving a satisfactory rate of success. A satisfactory functional amplitude is generally achieved with this implant and the elbow is generally pain free

Introduction A review of hip replacements performed in our hospital between 1991 and 2000 has identified a group of post-operative patients in whom recurrent dislocation has been deemed untreatable because of medical comorbidity. We tried to identify a group of patients at risk of recurrent dislocations. This paper presents our experience with the Kasselt cup in these patients. Methods We have used the Kasselt cup with indications being: a) prophylaxis, in patients with perceived greater risk of recurrent dislocation and b) treatment of recurrent (three or more) dislocations following THR. Patients were identified from clinical records and a National Joint Register. From 1998 to 2002, 51 patients underwent THR utilizing semi-constrained Kasselt cup. All living patients were invited for clinical and radiographic examination. Forty-eight patients (51 hips) were available for study. Thirty-nine patients were able to attend clinic and nine were interviewed by telephone. Average follow-up was 18.6 months (range 6 to 36 months). Average age was 75.6 years (range 56 to 92 years). Twenty-nine operations were done prophylactically and 22 for recurrent dislocations. Results Three patients suffered further dislocations, from the recurrent dislocation group. One suffered a single dislocation post-operatively which was reduced by close manipulation and to-date has not re-dislocated. The second continued to dislocate. The third was revised with a Kasselt cup for recurrent dislocation and suffered three further dislocations. This patient was re-revised and to-date (six months) has had no further dislocation. The mean Harris Hip Score in the whole group was 79 (range 49 to 100). We have seen no dislocation in patients in the ‘at risk’ group in this short term. Conclusion The value of this prosthesis remains uncertain

A review of total hip replacements (THR) performed in Palmerston North between 1991–2000 has identified a group of postoperative patients in whom recurrent dislocation has been previously deemed untreatable because of medical co-morbidity. From 1998 to 2001, 47 patients underwent THR utilizing a semi-constrained “Kasselt” cup to reduce the risk of dislocation. Indications for use of this cup were: Recurrent dislocation following primary or revision THR (3 or more dislocations) or perceived greater risk of recurrent dislocation eg. elderly, mental confusion, neurological compromise or fracture neck of femur. This paper presents the early results in these 47 patients (49 hips). Clinical records and radiographs of all hip replacement patients were retrospectively reviewed to identify the “Kasselt” group and telephone contact was made for permission to participate in the study. All living patients were sent a self-evaluation questionnaire and invitation to attend clinic for physical examination and radiographs of the hip joint. Twenty-one patients were recurrent dislocators and 24 were at risk patients. Out of 45 living patients 36 were physically examined between 6 and 36 months following surgery. All collected data was statistically analysed using StatWave software. Results: Forty-three of the 45 living patients (47 hips) had no dislocations following surgery. Two patients suffered further dislocation, both of whom were previously recurrent dislocators. One suffered a single dislocation postoperatively which was reduced closed and to date has not re-dislocated. The second continues to dislocate. The mean postoperative Harris Hip Score in the whole group is 79 (range 49–100). Early results reveal no dislocations in the “at risk” primary group

Introduction

Tibiofemoral constraint in patients with total knee replacements (TKR) is dependent on both implant geometry and the surrounding soft tissue structures. Choosing more highly constrained geometries can reduce the contribution of soft tissue necessary to maintain joint stability [1]. Often when knee revision surgeries are required, the soft tissue and bone are compromised leading to the use of more constrained implants to ensure knee stability [2]. The current study quantifies the differences in varus-valgus (VV) and internal-external (IE) constraint between two types of total knee revision systems: SIGMA® TC3© and ATTUNE® REVISION.

Introduction. The interaction between the mobile components of total elbow replacements (TER) provides additional constraint to the elbow motion. Semi-constrained TER depend on a mechanical linkage to avoid dislocation and have greater constraint than unconstrained TER that rely primarily in soft tissue for joint stability. Greater constraint increases the load transfer to the implant interfaces and the stresses in the polyethylene components. Both of these phenomena are detrimental to the longevity of TER, as they may result in implant loosening and increased damage to the polyethylene components, respectively[1]. The objective of this work was to compare the constraint profile in varus-valgus and internal-external rotation and the polyethylene stresses under loads from a common daily activity between two semi-constrained TER, Coonrad/Morrey (Zimmer-Biomet) and Discovery® (DJO), and an unconstrained TER, TEMA (LimaCorporate). Methods. We developed finite element (FE) models of the three TER mechanisms. To reduce computational cost, we did not include the humeral and ulnar stems. Materials were linear-elastic for the metallic components (E. Ti6Al4V. =114.3 GPa, E. CoCr. =210 GPa, v=0.33) and linear elastic-plastic for the polyethylene components (E=618 MPa, v=0.46; S. Y. =22 MPa; S. U. =230.6 MPa; ε. U. =1.5 mm/mm). The models were meshed with linear tetrahedral elements of sizes 0.4–0.6 mm. We assumed a friction coefficient of 0.02 between metal and polyethylene. In all simulations, the ulnar component was fixed and the humeral component loaded. We computed the constraint profiles in full extension by simulating each mechanism from 8° varus to 8° valgus and from 8° internal to 8° external rotation. All other degrees-of-freedom except for flexion extension were unconstrained. Then, we identified the instant during feeding that generated the highest moments at the elbow[2], and we applied the joint forces and moments to each TER to evaluate the stresses in the polyethylene. To validate the FE results, we experimentally evaluated the constraint of the design with highest polyethylene stresses in pure internal-external rotation and compared the results against those from a FE model that reproduced the experimental setup (Fig.1-a). Results. For each design, the constraint profiles in varus-valgus (Fig.2-a) were similar to internal-external rotation (Fig.2-b). All designs showed a lax zone in which the mechanisms rotated freely and an engagement zone in which the mobile components contacted, resulting in load transfer. The laxity of the Coonrad/Morrey and the Discovery® was similar and lower than that of the TEMA. After engagement, the stiffness of the TEMA was less than that of the Discovery® and the Coonrad/Morrey. The TEMA showed the lowest polyethylene stresses of all three designs under demanding loads during feeding. Only Discovery® and Coonrad/Morrey had zones reaching permanent deformation (Fig.3). For the Coonrad/Morrey, with the highest polyethylene stresses, the experimental and computational constraint profiles were similar (Fig.1-b). Discussion. The TEMA unconstrained design transferred less moment than semi-constrained designs, reducing the burden on the implant interfaces. Moreover, the TEMA design had lower stresses in the polyethylene components due to the combination of less constraint and a lack of sharp edges on the articular surfaces. For any figures or tables, please contact the authors directly

Even though spinal fusion has been used as one of the common surgical techniques for degenerative lumbar pathologies, high stiffness in the fusion segment could generate clinical complications in the adjacent spinal segment. To avoid these limitations of fusion, the artificial discs have recently used to preserve the motion of the treated segment in lumbar spine surgery. However, there have been lacks of biomechanical information of the artificial discs to explain current clinical controversies such as long-term results of implant wear and excessive facet contact forces. In this study, we investigated the biomechanical performance for three artificial discs in the lumbar spinal segments by finite element analysis. A three-dimensional finite element model of five spinal motion segments, from L1 to S, in intact lumbar spine was reconstructed from CT images. Finite element models of three artificial discs, semi-constrained and metal on polyethylene core type (ProDisc. ®. II, Spine Solutions Inc., USA; Type I), semi-constrained and metal on metal type (MaverickTM, Medtronic Sofamor Danek Inc., USA; Type II), and un-constrained and metal on polyethylene core type (SB ChariteTM III, Dupuy Spine Inc., Switzerland; Type III) were developed. Each artificial disc was inserted at L4–L5 segment, respectively. Upper and lower plates of artificial discs were attached on the L4 and L5 vertebrae. Some parts of ligaments and intervertebral disc in L4–L5 motion segment were removed to insert artificial discs. Nonlinear contact conditions were applied on facet joints in lumbar spine model and artificial discs. Bottom of sacrum was fixed on the ground and 5Nm of flexion and extension moments were applied on the superior plate of L1 with 400N of compressive load along follower load direction. In extension, all three artificial disc models showed higher rotation ratio at the surgical levels, but lower rotations at the adjacent levels than those in the intact model. There was no big difference of the intersegmental rotations among the artificial disc models. For the comparison of the peak von-Mises stresses on the polyethylene core in flexion, 52.3 MPa in type I implant was higher than 20.1 MPa in Type III implant while the peak von-Mises stresses were similar, 25.3 MPa and 26.5 MPa in Type I and III, respectively in extension. The facet contact forces at the surgical level for the artificial disc models showed 140 to 160 N in extension whereas the facet contact force in the intact model was 60 N. From the results of this study, we could investigate the biomechanical characteristics of three different artificial disc models. The relative rotation at the surgical level would be increases at the early outcome after total disk replacement. The semi-constrained type artificial disc could generate higher wear risk of the implant than unconstrained type. Also all types of artificial disc model have higher risk of facet joint arthrosis, and especially in the semi-constrained and metal on metal type. The results of the present study suggested that more careful care must be taken to choose surgical technique of total disc replacement surgery

Purpose: From 1985 to 2001, 31 total knee arthroplasties were performed for 17 adolescents or young adults with idiopathic juvenile osteoarthritis. The purpose of this work was to evaluate functional and radiological outcome. Material and methods: Overall functional outcome was assessed with the Steinbrocker classification. Knee function was evaluated with the IKS score. Several types of prostheses were implanted: constrained GSB (n=14), cemented semi-constrained tri-CCC tri-compartment with a rotatory platform (n=10), non-cemented semi-constrained ROCC (n=1), LCS (n=2) including non-cemented, and FINN (n=2) (two custom-made rotation hinge prostheses implanted in the same patient). Fourteen prostheses involved bilateral implants, including three dual implantation procedures. Results: Mean age at implantation was 20 years five months (14–29). There were fourteen girls and three boys. Eight had systemic idiopathic juvenile osteoarthritis and nine a polyarticular form. The Steinbrocker staging was: II (n=5,) III (n=6), IV or bedridden (n=4). Ten patients had two hip prostheses before bilateral knee arthroplasty. Mean follow-up was 4.5 years (1–12). Among the 31 operated knees, 16 were pain free, 14 minimally painful, and one painful due to loosening. The joint score was very good (n=18), good (n=4), and poor (n=5). Radiographically, normal alignment was found for 29 knees. Lucent lines were observed for 10 of the 14 GSB constrained prostheses. We did not observe any evidence of lucent lines for the non-cemented tri-compartment prostheses. Complications were: limited skin necrosis (n=1), bilateral supracondylar fracture one year after implantation (n=1). Discussion: Outcome has been encouraging for total knee prostheses in patients with idiopathic juvenile osteoarthritis. These arthroplasties allow spectacular functional improvement. The few series reported have also reported very good results. Cemented tri-compartment semi-constrained implants appear to provide better stability at five years. Biologically sealed tri-compartment prostheses would be a very satisfactory solution due to the preservation of bone stock

Total elbow arthroplasty (TEA) usage is increasing owing to expanded surgical indications, better implant designs, and improved long-term survival. Correct humeral implant positioning has been shown to diminish stem loading in vitro, and radiographic loosening in in the long-term. Replication of the native elbow centre of rotation is thought to restore normal muscle moment arms and has been suggested to improve elbow strength and function. While much of the focus has been on humeral component positioning, little is known about the effect of positioning of the ulnar stem on post-operative range of motion and clinical outcomes. The purpose of this study is to determine the effect of the sagittal alignment and positioning of the humeral and ulnar components on the functional outcomes after TEA. Between 2003 and 2016, 173 semi-constrained TEAs (Wright-Tornier Latitude/Latitude EV, Memphis, TN, USA) were performed at our institution, and our preliminary analysis includes 46 elbows in 41 patients (39 female, 7 male). Patients were excluded if they had severe elbow deformity precluding reliable measurement, experienced a major complication related to an ipsilateral upper limb procedure, or underwent revision TEA. For each elbow, saggital alignment was compared pre- and post-operatively. A best fit circle of the trochlea and capitellum was drawn, with its centre representing the rotation axis. Ninety degree tangent lines from the intramedullary axes of the ulna and humerus, and from the olecranon tip to the centre of rotation were drawn and measured relative to the rotation axis, representing the ulna posterior offset, humerus offset, and ulna proximal offset, respectively. In addition, we measured the ulna stem angle (angle subtended by the implant and the intramedullary axis of the ulna), as well as radial neck offset (the length of a 90o tangent line from the intramedullary axis of the radial neck and the centre of rotation) in patients with retained or replaced radial heads. Our primary outcome measure was the quickDASH score recorded at the latest follow-up for each patient. Our secondary outcome measures were postoperative flexion, extension, pronation and supination measured at the same timepoints. Each variable was tested for linear correlation with the primary and secondary outcome measures using the Pearson two-tailed test. At an average follow-up of 6.8 years (range 2–14 years), there was a strong positive correlation between anterior radial neck offset and the quickDASH (r=0.60, p=0.001). There was also a weak negative correlation between the posterior offset of the ulnar component and the qDASH (r=0.39, p=0.031), and a moderate positive correlation between the change in humeral offset and elbow supination (r=0.41, p=0.044). The ulna proximal offset and ulna stem angle were not correlated with either the primary, or secondary outcome measures. When performing primary TEA with radial head retention, or replacement, care should be taken to ensure that the ulnar component is correctly positioned such that intramedullary axis of the radial neck lines up with the centre of elbow rotation, as this strongly correlates with better function and less pain after surgery

Total shoulder arthroplasty has gone through several generations, as instruments and implant designs have given surgeons both more options in the alignment of the components and more guidance in the best choices to make. However, while the measurement of alignment has become more sophisticated, the importance of particular aspects of alignment to actual patient comfort and function has been less completely characterised. Overstuffing of the joint and proud humeral heads have been most associated with clinical failure. The efforts to avoid this can be divided into two camps: 1.) The anatomic school, who believe an experienced surgeon can divine the correct anatomy that existed before the distortions of arthritis began, and that the surgeon should make free-hand cuts and alignments to restore the normal anatomy. 2.) The cutting-guide school, who believe that average versions and positions avoid error and that soft-tissue balancing requires occasional deviations from “normal” anatomy. Reverse total shoulder replacement in contrast is a semi-constrained implant, with built-in “internal impingement” at the extremes of motion, which can cause notching and/or instability (levering out). Initial European experience favored placing the humeral component in 0 degrees, but most surgeons have gravitated toward 15–20 degrees of retroversion to allow easy conversion from/to a hemiarthroplasty as needed. Increased retroversion may block internal rotation, and increased anteversion limits external rotation

It is usually assumed that there is a correlation between the number of previous operations and the clinical outcome of revision knee arthroplasty though it has not been studied and published. We reviewed our series of 81 revision knee arthroplasty patients to ascertain if a correlation exists. All patients had a semi-constrained prosthesis implanted. Methods: We analysed the data of 81 revision knee arthroplasty patients performed at Wrightington Hospital with an average follow-up of 31 months (1yr – 6yrs). The number of previous operations on each knee were noted and the clinical outcome was determined using a patient satisfaction questionnaire. Results: Of the 81 patients; 18 were enthusiastic with the clinical outcome; 38 were satisfied; eight were non-committal; 17 were disappointed. Seventy four per cent of patients with one previous operation were enthusiastic or satisfied with the revision surgery outcome in comparison to 55.5% and 0% of patients with two and three previous surgery respectively. Conclusion: The trend from the above figures suggests that as the number of previous operations increases the likelihood of satisfactory clinical outcome decreases, in revision total knee replacement using semi-constrained prosthesis

Introduction. Reverse total shoulder arthroplasty (RTSA) is a semi-constrained joint replacement with an articulating cobalt-chromium glenosphere and ultra-high molecular weight polyethylene (PE). Because of its limited load bearing, surgeons and implant manufacturers have not elicited the use of highly cross-linked PE in the shoulder, and to date have not considered excessive PE wear in the reverse shoulder a primary concern. As the number of shoulder procedures is expected to grow exponentially in the next decade, however, it is important to evaluate how new designs and bearing materials interact and to have an understanding of what is normal in well-functioning joint replacements. Currently, no in vivo investigation into RTSA PE wear has been conducted, with limited retrieval and simulation studies. In vitro and in silico studies demonstrate a large range in expected wear rates, from 14.3 mm. 3. /million cycles (MC) to 126 mm. 3. /MC, with no obvious relationship between wear rate and polyethylene diameter. The purpose of this study is to evaluate, for the first time, both volumetric and linear wear rates in reverse shoulder patients, with a minimum six-year follow-up using stereo radiographic techniques. Methods. To date, seven patients with a self-reported well-functioning Aequalis Reversed II (Wright Medical Group, Edina, MN, USA) RTSA implant system have been imaged (mean years from surgery = 7.0, range = 6.2 to 9). Using stereo radiographs, patients were imaged at the extents of their range of motion in internal and external rotation, lateral abduction, forward flexion, and with their arm at the side. Multiple arm positions were used to account for the multiple wear vectors associated with activities of daily living and the shoulder's six degrees of motion. Using proprietary software, the position and orientation of the polyethylene and glenosphere components were identified and their transformation matrices recorded. These transformation matrices were then applied to the CAD models of each component, respectively, and the apparent intersection of the glenosphere into the PE recorded. Using previously validated in-house software, volumetric and maximum linear wear depth measurements were obtained. Linear regression was used to identify wear rates. Results. The volumetric and linear wear rates for the 36 mm PE liners (n = 5) were 39 mm. 3. /y (r. 2. = 0.86, range = 24 to 42 mm. 3. /y) and 0.09 mm/y (r. 2. = 0.96, range = 0.08 to 0.11 mm/y), respectively. Only two patients with 42 mm PE liners were evaluated. For these, volumetric and linear wear rates were 110 mm. 3. /y (r. 2. = 0.81, range = 83 to 145 mm. 3. /y) and 0.17 mm/y (r. 2. = 0.99, range = 1.12 to 1.15 mm/y), respectively. Conclusion. For the first time, PE wear was evaluated in the reverse shoulder in vivo. More patients are required for conclusive statements, but preliminary results suggest first order volumetric and linear wear rates within those predicted by simulation studies. It is interesting to note the increased wear with larger PE size, likely due to the increased contact area between congruent faces and the potential for increased sliding distance during arm motion

Purpose: We conducted a retrospective study of 20 total elbow prostheses GUEPAR humerocubital and humeroradial (G3) implanted in 19 patients with rheumatoid arthritis. This anatomic metal-polyethylene prosthesis is available in a left and right model and in two sizes, large and small. A radial head prosthesis is now available in addition to the humerocubital prosthesis. The radial head prosthesis has an intramedullary metallic stem and a mobile polyethylene cup which comes in several sizes. Material and methods: Among 20 prostheses implanted between 1997 and 2001, four were first-generation prostheses which did not have a radial head. At three to four years, these four prostheses developed valgus instability with deterioration of the polyethylene of the cubital piece requiring revision with a new generation GUEPAR associated with a radial head. This gave two good results and two failures revised with a semi-constrained prosthesis. For the 16 other cases of rheumatoid disease, the G3 humerocubital prosthesis associated with a radial head was inserted. These 16 prostheses were followed two years and were retained for this analysis. The posterior approach was used with inverted-V section of the triceps using the surgical technique recommended by the promoters. Patients had permanent severe to moderate pain. The Mayo Clinic score (1992 including daily life activities) was 33/100. Radiographically, seven elbows were Larsen grade III, nine grade IV, seven grade IIA and nine grade IIIb (Larsen classification modified by the Mayo Clinic). Results: All patients were reviewed with mean follow-up of two years (1–5). The Mayo Clinic score improved from 33/100 to33/90 with outcome considered excellent in 15 elbows and fair in one. Discussion: We recommend total elbow prostheses for rheumatoid arthritis patients. Semi-constrained prostheses have indications in certain cases of massive destruction, but the minimally or non-constrained gliding prostheses, such as the GUEPAR prosthesis, are part of the evolution of these prostheses, just as was the case for knee prostheses. These good results can be expected to persist over time

The aim of the study was to assess the results of treating knee osteoarthrosis with total knee arthroplasty (TKA) after previous tibia and/or femur fractures resulting in axial limb deformities. Thirty-six knees (34 patients) were operated on. At the most recent follow-up, 4.8 years after surgery, all but one patient demonstrated an improvement in both clinical and functional KSS. This male patient required revision after 2 years due to tibial component aseptic loosening. Improved range of motion was generally noted, especially extension, however, two patients with both tibia and femur fractures had worse results. TKA is an effective method of treatment for patients with arthrosis after a previous femur or tibia fractures. When deformity is severe semi-constrained or constrained, implants with extensions may be necessary

Controversy remains regarding the optimal treatment for iatrogenic injury to the medial collateral ligament (MCL) during primary total knee arthroplasty (TKA). Some authors have recommended converting to a prosthesis that provides varus/valgus constraint while others have recommended primary repair. In this study we report the results of a 45 patients who sustained intra-operative MCL injuries during primary TKA that were treated with primary repair. Of 3922 consecutive primary TKA there were 48 (1.2%) intra-operative MCL lacerations or avulsions. One patient was lost and one died before 24-month follow-up. All but one patient underwent primary repair with placement of components without varus/valgus constraint. This left 45 knees with a mean follow up of 89 months (range, 24 – 214 months). The mean HSS knee scores increased from 47 to 85 points (p<0.001). No patients had subjective complaints of instability. No patients had excessive varus/valgus laxity when tested in full extension and 30 degrees of flexion. The range of motion at the time of final follow-up averaged 110 degrees (range, 85 – 130 degrees). Five knees required treatment for stiffness with 4 knees undergoing manipulation under anesthesia and 1 knee undergoing open lysis of adhesions with polyethylene articular surface exchange. Two knees underwent revision for aseptic loosening of the tibial component. In the three knees that underwent open revision, the MCL was noted to be in continuity and without laxity. Primary repair with 6 weeks of post-operative hinged bracing after iatrogenic injury to the MCL during primary TKA was successful at preventing instability although stiffness was seen in approximately 10% of patients. The increased morbidity associated with implantation of a semi-constrained or constrained implant may be unwarranted in this situation

Controversy remains regarding the optimal treatment for iatrogenic injury to the medial collateral ligament (MCL) during primary total knee arthroplasty (TKA). Some authors have recommended converting to a prosthesis that provides varus/valgus constraint while others have recommended primary repair. In this study, we report the results of 45 patients who sustained intra-operative MCL injuries during primary TKA that were treated with primary repair. Of 3922 consecutive primary TKA there were 48 (1.2%) intra-operative MCL lacerations or avulsions. One patient was lost and one died before 24 months follow up. All but one patient underwent primary repair with placement of components without varus/valgus constraint. This left 45 knees with a mean follow up of 89 months (range, 24 to 214 months). The mean HSS knee scores increased from 47 to 85 points (p<0.001). No patients had subjective complaints of instability. No patients had excessive varus/valgus laxity when tested in full extension and 30 degrees of flexion. The range of motion at the time of final follow-up averaged 110 degrees (range, 85 to 130 degrees). Five knees required treatment for stiffness with 4 knees undergoing manipulation under anaesthesia and 1 knee undergoing open lysis of adhesions with polyethylene articular surface exchange. Two knees underwent revision for aseptic loosening of the tibial component. In the three knees that underwent open revision, the MCL was noted to be in continuity and without laxity. Primary repair with 6 weeks of post-operative hinged bracing after iatrogenic injury to the MCL during primary TKA was successful at preventing instability although stiffness was seen in approximately 10% of patients. The increased morbidity associated with implantation of a semi-constrained or constrained implant may be unwarranted in this situation