Introduction & aims

Total knee Arthroplasty has revolutionized the lifestyle of patients with end stage knee arthritis. This study was conducted to describe the outcome from patient's perspective one year after TKR and patient satisfaction in terms of post operative pain and functional outcome Also, to identify preoperative characteristics predicting post operative outcome.

Method

A prospective study was conducted at our institution (Dayanand Medical College and Hospital, Ludhiana) from 2010 to 2012. The study included 104 patients (74 females and 30 males) with 152 cemented TKR surgeries. The average age of the patients was 61.39 years. Out of 104 patients, 48 had bilateral TKR, 31 had left TKR and 25 had right TKR surgery. Knee injury and osteoarthritis outcome score (KOOS) and DMCH General Patient Questionnaire was used to analyse the satisfaction level, physical activity and quality of life one year after the TKR surgery.

Introduction & aims

Geriatric hip fractures are a challenging clinical problem throughout the world. Hip fracture services have been shown to shorten time to surgery, decrease the cost of admissions, and improve the outcomes. We instituted a geriatric hip fracture program for co management of these injuries by orthopedic and internal medicine teams at our hospital in India.

Method

From January 2010 till December 2011, 119 patients with a femoral neck fracture were treated with cemented modular hemiarthroplasty under this program using a cost-effective Indian implant. The cohort included 63 males and 56 females with a mean age of 70.7 years (range 55–98 years). Hypertension (n=42) and diabetes mellitus (n=29) were the most common co morbidities. The follow-up period ranged from 12 to 37 months with an average of 24 months.

Introduction & aims

Total hip replacement is an excellent treatment option for people with late stage degenerative hip disease. In addition to marked reduction in pain and improvement in sleep, most people regain range of motion, physical ability and quality of life. This study aimed at the functional outcomes of large diameter heads in THR patients.

Method

This study is an analysis of a cohort of patients undergoing total hip replacement performed at our hospital from November 2011 to July 2013. A total of 70 hips, 40 males and 30 females, were operated upon with large diameter femoral heads. The mean age was 50.38 years (range 40–59 years). In our cohort, 32 patients had AVN of femur head, 19 had post traumatic secondary degeneration, 10 had RA, 6 had AS and 3 patients had OA of hip. The follow-up data included local complications, Harris Hip Score, medical complications, readmission, activity status and use of a walking aid.

Background

Total Ankle Replacement (TAR) has become a common surgical procedure for severe Osteoarthritis of the ankle. Unlike hip and knee, current TARs still suffer from high failure rates. A key reason could be their non-anatomical surface geometry design, which may produce unnatural motion and load-transfer characteristics. Current TARs have articular surfaces that are either cylindrical or truncated cone surfaces following the Inman truncated cone concept from more than 60 years ago [1]. Our recent study demonstrated, that the surfaces of the ankle can be approximated by a Saddle-shaped, Skewed, truncated Cone with its apex directed Laterally (SSCL) [2]. This is significantly different than the surface geometry used in current TAR systems. The goal of this study was to develop and test the reliability of an in vitro procedure to investigate the effect of different joint surface morphologies on the kinematics of the ankle and to use it to compare the effect of different joint surface morphologies on the 3D kinematics of the ankle complex.

Methodology

The study was conducted on ten cadaver ankle specimens. Image processing software (Analyze Direct^TM) was used to obtain 3D renderings of the articulating bones. The 3D bone models were then introduced into engineering design software packages (, Geomagic^TM and Inventor^TM) to produce a set of four custom-fit virtual articular surfaces for each specimen: 1. Exact replica of the natural surfaces; 2. cylindrical; 3. truncated cone with apex oriented medially according to Inman's postulate; and 4. SSCL. The virtual TAR implants were exported to a 3D printing software and 3D physical models of each implant was produced in PLA using 3D printing (Figure 1). The intact cadaver was tested first in a specially design loading and measuring system [3] in which external moments were applied across the ankle in the three planes of motion and the resulting motion was measured through a surgical navigation system (Figure 1). Each of the four customized implant sets were then surgically introduced one at a time and the test was repeated. From the results, the ankle, subtalar and complex kinematics could be compared to that of the intact natural joint.

INTRODUCTION

Clinical studies have shown that the knee tends to experience laterally higher AP motion (posterior directed) than medially (Asano at al., 2001; Dennis et al., 2005; Hill et al., 2000; Moro Oka et al., 2007). Traditional posterior stabilized (PS) total knee arthroplasty (TKA) designs allow deep flexion stability and femoral rollback once cam/spine engagement occurs, however mechanical stability provided by tibial bearing conformity during early to mid-flexion is highly variable. In this study a computer knee model is used to compare AP kinematics in PS TKA designs while evaluating multiple sagittal tibia bearing conformities. We hypothesized that highly conforming designs would be necessary to promote AP stability prior to cam/spine engagement.

METHOD

A specimen specific computer model consisting of the femur, tibia and fibula, as well as the contribution of the ligaments and capsule was virtually implanted with TKA designs of the appropriate size at 5° tibia slope with the posterior cruciate ligament sacrificed. A single PS femoral component was evaluated with five PS tibia bearing designs with variable sagittal conformity ratios ranging from 1.05:1 to 2.2:1 (conformity ratio = tibia bearing sagittal radius / femur sagittal condylar radius). Designs were fully conforming frontally, with cam/spine engagement beyond 90° flexion. In all designs, lateral conformity ratios were increased relative to medial conformity ratios to facilitate lateral femoral rollback. Resultant AP kinematic predictions were obtained for femoral Low Points (LP) during 1) envelope of motion during internal external (IE) laxity evaluation and 2) knee bend functional activity.

INTRODUCTION

The intact, healthy human knee joint is stable under anterior-posterior (AP) loading but allows for substantial internal-external (IE) laxity. In vivo clinical studies of the intact knee consistently demonstrate femoral rollback with flexion (Hill et al., 2000, Dennis et al., 2005). A tri-condylar, posterior stabilized (PS) total knee arthroplasty (TKA) with a rotating platform bearing (TKA-A) has been designed to address these characteristics of the intact knee. The third condyle is designed to guide the femoral component throughout the entire flexion arc (AP stability and femoral rollback with flexion), while the rotating platform bearing allows for IE rotation.

This study used a computer model to compare the AP and IE laxity of a new TKA-A to that of two clinically established TKAs (TKA-B: rotating PS TKA, TKA-C: fixed PS TKA) and to demonstrate improvements in AP stability, IE rotation, and femoral rollback.

METHODS

A specimen-specific, robotically calibrated computer knee model (Siggelkow et al., 2012), consisting of the femur, tibia and fibula as well as the kinetic contribution of the ligaments and capsule was virtually implanted with appropriate sizes of TKA-A, TKA-B and TKA-C adhering to the respective surgical techniques. A similar extension gap was targeted for all designs.

The following kinematic data resulting from applied loads and moments were analyzed: 1) Passive AP and IE laxity (AP load: ± 50 N, IE moment: ± 6 Nm) of the midpoint between the flexion facet centers (Iwaki et al., JBJS, 2000) under low compression (44 N), 2) AP position of the medial and lateral low points (LP) of the femoral component during a lunge motion (Varadarajan et al., 2008).

Introduction

Well-balanced soft tissue is essential for achieving a good result when performing total knee arthroplasty. The preoperative planning is critical for ensuring a good operation. This study evaluated the preoperative distractive stress radiographs in order to quantify and predict the extent of medial release according to the degree of varus deformity in primary total knee arthroplasty.

Methods

We evaluated 120 varus, osteoarthritic knee joints (75 patients). The association of the angle on the distractive stress radiograph with extent of medial release was analyzed. The extent of medial release was classified into the following 4 groups according to the stage: release of the deep medial collateral ligament (group 1), release of the posterior oblique ligament and/or semimembranous tendon (group 2), release of the posterior capsule (group 3) and release of the superficial medial collateral ligament (group 4).

Introduction

The acquisition of proper soft tissue balance is one of the crucial factors for preventing long-term failure and obtaining successful treatment outcomes of total knee arthroplasty (TKA). Medial collateral ligament (MCL) release is essential for encountering severe varus deformity. However, conventional subperiosteal MCL release for severe varus deformity can cause the complete detachment of MCL. This study compared retrospectively the results of complete distal release of the MCL with those of medial epicondylar osteotomy during ligament balancing in varus knee TKA

Methods

This study retrospectively reviewed 9 cases of complete distal release of the MCL (group 1) and 11 cases of medial epicondylar osteotomy (group 2) which were used to correct severe medial contracture. The clinical assessment was based on the American Knee Society knee score (KS), function score (FS), and the ROM preoperatively and at the final follow-up. For the radiological assessment, the femorotibial angle was measured based on the whole lower extremity radiograph preoperatively and at the final follow-up. Three months after surgery and at the final follow-up, medial instability was assessed using the valgus stress radiographs, in which the contralateral side was compared using Telos (Telos, Weterstadt, Germany).

Purpose

Previous retrieval studies demonstrate increased tibial baseplate roughness leads to higher polyethylene backside wear in total knee arthroplasty (TKA). Micromotion between the polyethylene backside and baseplate is affected by the locking mechanism design and can further increase backside wear. This study's purpose was to examine modern locking mechanisms influence, in the setting of both polished and non-polished tibial baseplates, on backside tibial polyethylene damage and wear.

Methods

Five TKA models were selected with different tibial baseplate and/or locking mechanism designs. Six retrieval tibial polyethylenes from each TKA model were matched based on time in vivo (TIV), age at TKA revision, BMI, gender, number of times revised, and revision reason. Two observers visually assessed each polyethylene. Primary outcomes were visual damage scores, individual visual damage modes, and linear wear rates determined on micro-computed tomography (micro-CT) scan in mm/year. Demographics were compared by one-way ANOVA. Damage scores, damage modes, and linear wear were analyzed by the Kruskal-Wallis test and Dunn's multiple comparisons test.

BACKGROUND

The need for post-operative manipulation under anesthesia (MUA) for stiffness after primary total knee arthroplasty is a frustrating complication that can lead to suboptimal outcomes if range-of-motion to a functional level is not regained. Implant morphology and kinematics, PCL imbalance, and soft-tissue balancing can all contribute to post-operative stiffness. Utilization of total knee arthroplasty components that replicate the native knee's medial ball and socket kinematics may lead to easier maintenance of flexion post-operatively compared to conventional components.

PURPOSE

To determine if a medial pivot total knee arthroplasty design can reduce the need for post-operative MUA after primary total knee arthroplasty.

Introduction

Total ankle replacement (TAR) is surgically complex; malalignment can arise due to surgical technique or failure to correct natural varus/valgus malalignment. Across joint replacement, malalignment has been associated with pain, component edge loading, increased wear and higher failure rates. Good component alignment is considered instrumental for long term TAR success. The conforming surface geometry of mobile bearing TARs leaves no freedom for coronal plane malalignment. The aim of this study was to investigate the biomechanical effect of coronal alignment on a mobile bearing TAR.

Methods

Three TARs (Zenith, Corin Group) were tested under five coronal malalignment angles from 0–10° in a single station electromechanical knee simulator applying a typical ankle gait profile. As swing phase load is critical to TAR contact mechanics but will vary depending on the joint laxity. Swing loads of 100N, 300N and 500N were investigated. A positive control test with a swing load of 1000N was also studied, and was expected to eliminate the majority of lift off effects. Under each condition, the version was allowed to move freely while tests were performed, and the version profile under each alignment angle was recorded. Each test was carried out for 600 cycles in 25% bovine serum. Under the same loading conditions, but without lubrication, a Tekscan sensor recorded data from two cycles to assess the change in contact pressure and area at the five coronal angles.

Introduction

Wear plays a key role in the clinical outcome of total hip replacements (THR). In addition, increased frictional moment can stress the implant interfaces which may lead to high torsional loadings in the intermodular taper junction (fretting) and cup loosening and to the development of noise (squeaking). Against the background of larger head diameters (increased range of motion and decreased risk of dislocation), the friction induced by the joint articulation is of particular interest. As of now, the investigation of friction with the use of relevant joint kinematics and loadings are limited to numerical studies. Experimental approaches use simplified models which do not take into consideration complex activities. Thus, with the aim of this study is the identification of articular frictional moments that consider critical in vivo loading conditions and kinematics as well as the clinical cup inclination, head size and clearance of ceramic-on-ceramic hip bearings.

Materials and Methods

A standard hip simulator (Minibionix 852 with 4 DOF Hip setup, MTS, Eden Prairie, USA) was modified in order to allow for high-precision friction measurements during head-insert articulation in all 6 DOF (MC2.5D-500, AMTI, Boston, USA). Disturbing systemic effects have been minimized by using quasi frictionless aerostatic lateral force compensation (Eitzenberger, Wessobrunn, Germany) and cross talk compensation. Beside the standard protocoll for in vitro wear assessment (ISO 14242-1), more complex profiles from in vivo patient data (Heidelberg Motion Lab and Orthoload database) have been used: normal walking with different walking speeds and patient's weights, stairs up/down and start-stop conditions. All-ceramic bearings (Biolox delta, Ceramtec, Plochingen, Germany) have been orientated in clinically relevant cup inclinations (30, 45, 60 and 75 deg). For each head diameter (28, 36 and 48 mm) n=8 specimens have been devided in two groups: small and large clearance according to the manufacturer's specification. All tests were run at 37°C in diluted bovine serum (20 g/l protein content).

Introduction

Navigation in total hip arthroplasty (THA) has the goal to improve accuracy of cup orientation. Measurement of cup orientation on conventional pelvic radiographs is susceptible to error due to pelvic malpositioning during acquisition. A recently developed and validated software using a postoperative radiograph in combination with statistical shape modelling allows calculation of exact 3-dimensional cup orientation independent of pelvic malpositioning.

Objectives

We asked (1) what is the accuracy of computer-navigated cup orientation (inclination and anteversion) and (2) what is the percentage of outliers (>10° difference to aimed inclination and anteversion) using postoperative measurement of 3-dimensional cup orientation.

Introduction

Hips following in-situ pinning for slipped capital femoral epiphysis (SCFE) have an altered morphology of the proximal femur with cam type deformity. This deformity can result in femoroacetabular impingement and early joint degeneration. The modified Dunn procedure allows to reorientate the slipped epiphysis to restore hip morphology and function.

Objectives

To evaluate (1) hip pain and function, (2) 10-year survival rate and (3) subsequent surgeries and complications in hips undergoing modified Dunn procedure for SCFE.

Introduction

Total ankle replacement (TAR) is less successful than other joint replacements with a 77% survivorship at 10 years. Predominant indications for revision include: Insert dislocation, soft tissue impingement and pain/stiffness. Insert edge-loading may be both a product and cause of these indications and was reported to affect 22% of patients with the, now withdrawn from market, Ankle Evolutive System (AES) TAR (Transysteme, Nimes, France). Compressive forces up to seven times body weight over a relatively small contact area (∼6.0 to 9.2 cm²), in combination with multi-directional motion potentially causes significant polyethylene wear and deformation in mobile-bearing TAR designs. Direct methods of measuring component volume (e.g. pycnometer) use Archimedes' principle but cannot identify spatial changes in volume or form indicative of wear/deformation. Quantitative methods for surface analysis bridge this limitation and may advance methods for analysing the edge loading phenomena in TAR.

Aim

Determine the frequency of edge loading in a cohort of explanted total ankle replacements and compare the quantitative surface characteristics using a novel explant analysis method.

INTRODUCTION

Although several meta-analyses have been performed on total knee arthroplasty (TKA) using computer-assisted orthopaedic surgery (CAOS) [1], understanding the inter-site variations of the surgical profiles may improve the interpretation of the results. Moreover, information on the global variations of how TKA is performed may benefit the development of CAOS systems that can better address geographic-specific operative needs. With increased application of CAOS [2], surgeon preferences collected globally offers unprecedented opportunity to advance geographic-specific knowledge in TKA. The purpose of this study was to investigate geographic variations in the application of a contemporary CAOS system in TKA.

Materials and Methods

Technical records on more than 4000 CAOS TKAs (ExactechGPS, Blue-Ortho, Grenoble, FR) between October 2012 and January 2016 were retrospectively reviewed. A total of 682 personalized surgical profiles, set up based on surgeon's preferences, were reviewed. These profiles encompass an extensive set of surgical parameters including the number of steps to be navigated, the sequence of the surgical steps, the definition of the anatomical references, and the parameters associated with the targeted cuts. The profiles were compared between four geographic regions: United States (US), Europe (EU), Asia (AS), and Australia (AU) for cruciate-retaining (CR) and posterior-stabilized (PS) designs. Clinically relevant statistical differences (CRSD, defined as significant differences in means ≥1°/mm) were identified (significance defined as p<0.05).

INTRODUCTION

Despite that computer-assisted orthopaedic surgery (CAOS) has been shown to offer increased accuracy to the bony resections compared to the conventional techniques [1], previous studies of CAOS have mostly focused on alignment outcomes based on a small number of patients [1]. Although several recent meta-analyses on the CAOS outcomes have been reported [2], these analyses did not differentiate between systems, while system-dependency has been reported to influence alignment parameters [3]. To date, no study has benchmarked a specific CAOS system based on a large number of clinical cases. The purpose of this study is to assess the accuracy and precision of bony resection in more than 4000 cases using a specific contemporary CAOS system.

Materials and Methods

Technical logs of 4292 TKAs performed between October 2012 and January 2016 using a contemporary CAOS system (ExactechGPS, Blue-Ortho, Grenoble, FR) were analyzed. The analyses were performed on: 1) planned resection, defined by the surgeon prior to the bone cuts. These parameters serve as inputs for the CAOS guidance; and 2) Checked resection, defined as digitalization of the actual resection surfaces by manually pressing an instrumented checker onto the bony cuts. Deviations in alignment and resection depths (on the referenced side) between planned and checked resections were calculated in coronal and sagittal planes for both tibia and femur (planned vs checked).

Purposes

To compare the acetabular component size relative to the patient's native femoral head size between conventional THA (CTHA) approach and robotic-guided THA (RGTHA) to infer which of these techniques preserves more acetabular bone.

Methods

Patients were included if they had primary osteoarthritis (OA) and underwent total hip replacement between June 2008 and March 2014. Patients were excluded if they had missing or rotated postoperative anteroposterior radiographs. RGTHA patients were matched to a control group of CTHA patients, in terms of pre-operative native femoral head size, age, gender, body mass index (BMI) and approach. Acetabular cup size relative to femoral head size was used as a surrogate for amount of bone resected. We compared the groups according to two measures describing acetabular cup diameter (c) in relation to femoral head diameter (f): (1) c-f, the difference between cup diameter and femoral head diameter and (2) (c-f)/f, the same difference as a fraction of femoral head diameter.

Introduction

The use of narcotic medications to manage postoperative pain after TJA has been associated with impaired mobility, diminished capacity to engage in rehabilitation, and lower patient satisfaction [1]. In addition, side effects including constipation, dizziness, nausea, vomiting and urinary retention can prolong post-operative hospital stays. Intraarticular administration of local anesthetics such as bupivacaine – part of a multimodal postoperative pain management regimen – reduces pain and lowers patients' length of stay [2]. In addition to its anesthetic activity, bupivacaine also has antibacterial activity, particularly against gram-positive bacteria [3]. We have developed a bupivacaine-eluting ultrahigh molecular weight polyethylene (Bupi-PE) formulation; we hypothesized that elution of bupivacaine from polyethylene could have both anesthetic and antibacterial effects in vivo.

Methods

Introduction

About 2% of primary total joint replacement arthroplasty (TJA) procedures become infected. Periprosthetic joint infection (PJI) is currently one of the main reasons requiring costly TJA revisions, posing a burden on patients, physicians and insurance companies.¹ Currently used drug-eluting polymers such as bone cements offer limited drug release profiles, sometimes unable to completely clear out bacterial microorganisms within the joint space. For this study we determined the safety and efficacy of an antibiotic-eluting UHMWPE articular surface that delivered local antibiotics at optimal concentrations to treat PJI in a rabbit model.

Materials and Methods

Skeletally mature adult male New Zealand White rabbits received either two non-antibiotic eluting UHMWPE (CONTROL, n=5) or vancomycin-eluting UHMWPE (TEST, n=5) (3 mm in diameter and 6 mm length) in the patellofemoral groove (Fig. 1). All rabbits received a beaded titanium rod in the tibial canal (4 mm diameter and 12 mm length). Both groups received two doses of 5 × 10⁷ cfu of bioluminescent S. aureus (Xen 29, PerkinElmer 119240) in 50 µL 0.9 % saline in the following sites: (1) distal tibial canal prior to insertion of the rod; (2) articular space after closure of the joint capsule (Fig. 1). None of the animals received any intravenous antibiotics for this study. Bioluminescence signal (photons/second) was measured when the rabbits expired, or at the study endpoint (day 21). The metal rods were stained with BacLight^® Bacterial Live-Dead Stain and imaged using two-photon microscopy to detect live bacteria. Hardware, polyethylene implants and joint tissues were sonicated to further quantify live bacteria via plate seeding.

Background

Patellofemoral complications have dwindled with contemporary total knee designs that market anatomic trochlear grooves that intend to preserve normal patella kinematics. While most reports of patellofemoral complications address patella and its replacement approach, they do not focus on shape of trochlear grooves in different prostheses [1]. The purpose of this study was to characterize 3D geometry of trochlear grooves of contemporary total knee designs (NexGen, Genesis II, Logic, and Attune) defined in terms of sulcus angle and medial-lateral offset with respect to midline of femoral component in coronal view and to compare to those of native femurs derived from 20 osteoarthritic patient CT scans.

Materials and Methods

Using 3D models of each implant and native femur, sulcus location and orientation were obtained by fitting a spline to connect sulcus points marked at 90°, 105°, 130°, and 145° of femoral flexion (Fig A). Implant reference plane orientations were established using inner facets of distal and posterior flanges. Reference planes of native femurs were defined using protocols developed by Eckhoff et al. [2] where coronal plane was defined using femoral posterior condyles and greater trochanter. In the coronal plane, a best fit line was used to measure sulcus angle and medial-lateral offset with respect to midline at the base of trochlear groove (Fig B).

BACKGROUND

Early dislocation is a foremost complication of total hip arthroplasty through a postero-lateral approach. The extra-articular impingement of the anterior part of the great trochanter with ileum bone, with or without soft tissue interposition is a well recognized but underestimated etiopathogenetic cause reported in literature. In this retrospective study through the assessment of clinical and radiographic follow-up at a minimum of six months, the effectiveness of an antero- longitudinal osteotomy of the great trochanter for early dislocation prevention is evaluated.

MATERIALS AND METHODS

209 patients (48.3% males and 51,7% females) underwent a total hip arthroplasty from June 2011 to September 2015, with surgery being performed by the same surgeon. A modified posterolateral approach was used according to the tissue-sparing criteria, in all the cases an anterior longitudinal osteotomy of the great trochanter has been performed at 90° to the antiversion angle of the implant and aligned posteriorly with the prosthesis. All the patients underwent a clinical and radiological follow up at one, three, and six months.

Methods

The brace works by strapping a femoral component tightly to a polyethylene insert by applying compression force between the sole of the foot and the thigh. Holes of 1, 2, 5, 10 mm in diameter and 0.1, 0.2, 0.5 and 1 mm in depth were created in the posteromedial part of polyethylene inserts. The inserts were provided from Teijin-nakashima Co. ltd. (Jodo, Okayama, Japan). The Hi-tech knee artificial joint (Teijin-nakashima Co. ltd.) was applied to a cadaveric knee and CT images of the knee were taken with a combination of insets with varying diameters and depths holes, using Aquilion ONE (Toshiba Medical Systems Corporation, Ohtawara, Japan). The finding conditions were as follows, Voltage; 120V, Current; 5A, slice thickness; 0.5 mm helical. The patient, who received total knee arthroplasty over 15 years ago, wore the brace and was examined using computed tomography. Afterward, the patient received revision surgery to replace the worn insert into new one. The removed insert was measured with a three-dimensional measuring machine (Cyclon, Mitsutoyo Co. ltd., Kawasaki, Japan).

Results

At a 1.0 mm depth, all holes could be detected. At a 0.5 mm depth, holes of 2, 5, 10 mm in diameter could be detected. At a 0.1∼0.2 mm depth, there was no hole detected. After revision surgery, a three-dimensional measuring machine revealed a 1.8 mm thickness of the insert on the medial side. The CT reconstruction image showed a1.84 mm thickness similar to the virtually measured figure.

Background

One of the serious postoperative complications associated with joint replacement is bacterial infection. In our recent investigations, iodine supported titanium implants demonstrated antibacterial activity in both in vitro studies and clinical trials. But it is not clear whether iodine treated titanium implants produce strong bonding to bone. This study evaluated the bone bonding ability of titanium implants with and without iodine surface treatments.

Methods

Titanium rods were implanted in intramedullary rabbit femur models, in regard to the cementless hip stem. The implant rods were 5mm in diameter and 25mm in length. Half of the implants were treated with iodine (ID implants) and the other half were untreated (CL implants). The rods were inserted into the distal femur; ID implants into the right femur and CL implants into the left. We assessed the bonding strength by a measuring pull-out test at 4, 8, and 12 weeks after implantation. The bone-implant interfaces were evaluated at 4 weeks after implantation.

Introduction

The management of peri-prosthetic distal femur fractures following TKR (Total Knee Replacement) in the elderly remains a challenge with little or no consensus on the best available treatment. Various methods have been described in the management of these complex fractures. Our study compares the outcome and cost of distal femoral arthroplasty to that of Fixation (Plating/Retrograde Nailing).

Methods

We retrospectively reviewed our database for patients admitted with peri-prosthetic distal femoral fractures between 2005–2013 (n=61). The patients were stratified into 2 groups based on method of management. The Distal Femoral Arthroplasty group (Group A) had 21 patients, with a mean age of 78 years (68–90. The Fixation group (Group B) had 40 patients, with a mean age of 74 years, 23 of those had plating of the fracture, while 17 had a retrograde nail inserted.

Pain scores, Length of stay, intra-operative blood loss, and weight bearing status, were compared. Functional outcomes were also assessed using Oxford knee scores, KSS scores, VAS pain assessment and range of motion from last follow up appointment. Minimum follow-up was 2 years.

Cost analysis was done for both groups, which included implant costs, consumable costs (man power included), theatre utilisation time and length of hospital stay. The calculation was done based on the PbR (payment by results) system and “best practise tariffs 2010–11” utilised by the NHS (National Health Service) in England.

Introduction

Despite several studies, controversies prevailed about the rate of complications following one-stage and two-stage bilateral total hip arthroplasty (THA). In current prospective study, we compared the complications and functional outcomes of one-stage and two-stage procedures.

Methods

One hundred and eighty patients (ASA class I or II) with bilateral hip osteoarthritis were assigned randomly to two equal groups. Two groups were matched in term of age and sex. All of the surgeries were performed through the Harding approach using uncemented implants. In two-stage procedures, surgeries were performed with 6 months to one year interval. All patients were evaluated one year postoperatively.

Background

Total joint replacement surgery is associated with large amounts of blood loss and significant rates of transfusions. Postoperative bleeding is one of the most important problems after major orthopedic surgeries including revision Total Hip Arthroplasty (THA). It has been demonstrate that Tranexamic acid is a useful agent to control the volume of blood loss. However, the more effective route of TXA administration remained controversial.

Methods

In current study, we compared the effects of local and intravenous(IV) administration of TXA on need to blood transfusion and hemoglobin drop. We randomized 80 patients undergoing revision THA into two groups: local group and IV group. In group IV 40 patients was administrated TXA 4 g alone systemically and in local group 40 patients the joint was irrigated with 4 g of TXA plus 0.33mg DEP (1:200,000).

Introduction

Failure of intertrochanteric fracture fixation often occurs in patients, who have poor bone quality, severe osteoporosis, or unstable fracture patterns. Hip arthroplasty is a good replacement procedure even though it involves technical issues such as implant removal, bone loss, poor bone quality, trochanteric nonunion and difficulty of surgical exposure. The purpose of this study is to evaluate the outcomes of total hip arthroplasty (THA) as the replacement for failed fixation of intertrochanteric fractures of the femur.

Patients and Methods

203 patients of failed intertrochanteric fractures between April 2009 and October 2014 were included in the study. All of them underwent total hip arthroplasty through direct lateral approach. 150 patients were male (73.8%) and 53 patients (26.1%) were female and the mean of age was 59.02±10.34 years old (range: 56–90 years). The indications of the failure were nail cut out in 174 (85.7%), non-union in 15 (7.3%), plate failure in 14 cases (6.8%). One patient underwent two-stage protocol due to infection. We evaluated the possible clinical and radiological complications and measured functional outcome with modified Harris hip score (MHHS). We used cementless cup in nearly all of patients (95.2%), cementless long stem in 88.1% of patients.

Introduction

Compared with the cruciate-retaining (CR) insert for total knee arthroplasty (TKA), the cruciate-substituting (CS) insert has a raised anterior lip, providing greater anterior constraint, and thus, can be used in cases of posterior cruciate ligament (PCL) sacrifice. However, studies have shown that the PCL maintains femoral rollback during flexion, acts as a stabilizer against distal traction force and aids knee joint proprioception; therefore, the argument for PCL excision in CS TKA remains controversial. The purpose of this study was to analyze CS TKA kinematics and identify the role of the PCL.

Methods

Seven fresh-frozen lower-extremity cadaver specimens were analyzed using Orthomap^® Precision Knee Navigation software (Stryker Orthopaedics, Mahwah, NJ, USA). They were surgically implanted with Triathlon^® components (Stryker Orthopaedics). The CS insert has a raised anterior lip, and the posterior geometry shares the same profile as the CR, so we can choose retaining or sacrificing the PCL. Six patterns were analyzed: (1) natural knee; (2) only anterior cruciate ligament excision; (3) CS TKA, PCL retention, and bony island preservation; (4) CS TKA, PCL retention, and bony island resection; (5) CS TKA and PCL excision; and (6) CR TKA and PCL excision. Center of the knee and center of the proximal tibia were registered using navigation system, and the magnitudes of the condylar translation were evaluated. And then, using trigonometric function, the magnitude of anterior-posterior translation of the femur was calculated.

Introduction

Patients with hip osteoarthritis have a substantial loss of muscular strength in the affected limb compared to the healthy limb preoperatively, but there is very little quantitative information available on preoperative muscle atrophy and degeneration and their influence on postoperative quality of life (QOL) and the risk of falls. The purpose of the present study were two folds; to assess muscle atrophy and degeneration of pelvis and thigh of patients with unilateral hip osteoarthritis using computed tomography (CT) and to evaluate their impacts on postoperative QOL and the risk of falls.

Methods

We used preoperative CT data of 20 patients who underwent primary total hip arthroplasty. The following 17 muscles were segmented with our developed semi-automated segmentation method: iliacus, gluteus maximus, gluteus medius, gluteus minimus, rectus femoris, tensor facia lata, adductors, pectinus, piriformis, obturator externus, obturator internus, semimenbranosus, semitendinosus, vastus medialis and vastus lateralis/intermedius (Fig. 1). Volume and radiological density of each muscle were measured. The ratio of those of affected limb to healthy limb was calculated. At the latest follow-up, the WOMAC score was collected and a history of falls after surgery was asked. The average follow- up period was 6 years.

Comparison of the volume and radiological density of each muscle between affected and healthy limbs was performed using the Wilcoxon signed rank test. Correlations between the volume and radiological density of each muscle and each score of the WOMAC were evaluated with Spearman's correlation coefficient. The volume and radiological density of each muscle between patients with and without a history of falls were compared using Mann-Whitney U test.

Background

Post-operative (postop) lower limb alignment in unicompartmental knee arthroplasty (UKA) has been reported to be an important factor for postop outcomes. Slight under-correction of limb alignment has been recommended to yield a better clinical outcomes than neutral alignment. It is useful if the postop limb alignment can be predicted during surgery, however, little is known about the surgical factors affecting the postop limb alignment in UKA. The purpose of this study was to examine the influence of the medial tibial joint line elevation on postop limb alignment in UKA.

Methods

Seventy-four consecutive medial UKAs were enrolled in this study. All the patients received a conventional fixed bearing UKA. Pre-operative (preop) and postop limb alignment was examined using long leg radiograph and lower limb alignment changes were calculated. Femoral and tibial osteotomy thickness were measured during surgery. Medial tibial joint line change was defined as polyethylene thickness minus tibial osteotomy thickness and sawblade thickness (1.27mm). Positive values indicated a tibial joint line elevation. Medial femoral joint line change was defined as femoral distal component thickness (6.5mm) minus femoral distal osteotomy thickness and sawblade thickness. Positive values indicated a femoral joint line reduction. Medial joint distraction width was also calculated by tibial joint line elevation plus femoral joint line reduction. The correlation of lower limb alignment change with polyethylene insert thickness, the medial tibial joint line elevation, femoral joint line reduction, or joint distraction width were analyzed.

INTRODUCTION

Recently, the short stem has become popular in total hip arthroplasty (THA). The advantages of the short stem are that it preserves femoral bone stock, possibly results in less thigh pain, and is suitable for minimally invasive THA. However, because of the short stem, malposition may happen during surgery. The purpose of this study was to compare the stem alignment, which was measured by CT, between the standard tapered round stem and the shorter tapered round stem.

MATERIALS AND METHODS

CT evaluation was performed in 28 patients (29 joints) who underwent primary THA. The standard tapered round stem (Bicontact D stem) was used in 13 patients. The shorter stem (Bicontact E stem) was used in 16 patients (17 joints). The proximal shapes of these two stems have almost the tame curvature. The mean age at surgery was 68 years. The mean BMI at surgery was 23.3 kg/m². Eighteen patients had osteoarthrosis, 3 patients had osteonecrosis, and 1 patient had femoral neck fracture. All surgeries were performed in the supine position with the direct anterior approach. The OrthoPilot imageless navigation system was used during surgery. Evaluation of the stem antetorsion angle (AA), flexion angle (FA), and varus angle (VA) were carried out.

Objective

Bacterial infection is a serious complication after joint replacement surgery. In particular, methicillin-resistant Staphylococcus aureus (MRSA) and epidermidis(MRSE) are very difficult to eradicate in infected prosthetic joint. Therefore, the retention rate of initial prosthesis affected with such resistant microorganisms is still low. Gentian violet shows potent antibacterial activity against gram-positive cocci as minimal bactericidal concentration is less than 0.1 %. In the present study, we investigated the efficacy of treatment with gentian violet against MRSA and MRSE infections after THA, TKA, and bipolar hip hemiarthroplasty (BHP).

Methods

There were 8 patients in this study; five patients with deep periprosthetic MRSA infection (2 THA, 2 BHP, 1 revision TKA); 3 patients with MRSE infection (1 revision THA, 1 BHP, 1 TKA). When infection was suspected after the surgery, we quickly obtained synovial fluid and periprosthetic soft tissue from the joint and applied to culture and microscopic examinations for detection of microorganisms. After identification of bacterial species, we immediately debrided the affected joint and washed thoroughly twice with 0.1% solution of gentian violet for 3 minutes each, followed by intra-articular multiple injection of arbekacin sulfate solution. Then we inserted an aspiration tube into the joint and administered appropriate antibiotics intravenously. If the inflammatory symptoms persisted in spite of the first treatment, we repeated the treatment until inflammation signs and intra-articular microorganisms could not be detected.

Introduction

We have compared the middle-term (average follow-up period; 10 years) clinical results of the K-MAX HS-3 tapered stem with those of the previous type having cylindrical tip.

Materials and Methods

In K-MAX HS-3 THA (Kyocera Medical, Kyoto, Japan), cemented titanium alloy stem and all polyethylene cemented socket are used. This stem has the double tapered symmetrical stem design, allowing the rotational stability and uniform stress distribution (Type T) (Fig. 1). The features of this stem are; 1. Vanadium-free high-strength titanium alloy (Ti-15Mo-5Zr-3Al), 2. Double-tapered design, 3. Smooth surface (Ra 0.4μm), 4. Broad proximal profile, 5. Small collar. In contrast, previous type stem, which was made of the same smooth-surface titanium alloy, has the design with cylindrical stem tip, allowing the maximum filling of the femoral canal (Type C) (Fig. 2). Osteolysis at the distal end of the stem had been reported in a few cases in Type C, probably due to the local stress concentration. Therefore the tapered stem was designed, expecting better clinical results.

All surgery was performed at Kitano Hospital between September 2003 and June 2006. 72 THA were performed (Type T; 52 hips, Type C; 20 hips). The average age of the patients at the operation was 61 and 69 years and the average follow-up period was 10.1 and 10.4 years for the Type T and C, respectively. The all-polyethylene socket was fixed by bone cement, and the femoral head material was alumina or CoCr (22 or 26 mm).

Background

The indication of unicompartmental knee arthroplasty (UKA) for end-stage osteoarthritis (OA) remains controversial. This study aimed to investigate patient reported outcomes (PROs) of UKA in patients with severe varus deformity of the knee and compare the results with those of total knee arthroplasty (TKA) at mid-term follow up.

Methods

A total of 96 TKAs of 69 patients and 61 UKAs of 50 patients were included. All patients presented with severe knee OA with hip-knee-ankle angle (HKA) ranged from −25 degree to −10 degree, preoperatively. Mean HKAs in TKA group and UKA group were −14.95º and −13.38º, respectively. PROs were assessed using Knee Society Score (KSS 2011), PainDETECT score (PD), and Pain Catastrophizing Scale (PCS) at a mean follow up of 58.65 months for TKA and 58.05 months for UKA. Kaplan-Meier survival analysis was performed to assess implant survival. Complication rate was also assessed. All data were compared between TKA group and UKA group.

Background

Currently, stailess steel, titanium and carbon-fiber reinforced polyetheretherketone (CF-PEEK) plates are available for the treatment of distal radius fractures. Since the possibility to create a less rigid fixation may represent an advantage in case of ostheoporotic or poor quality bone, the aim of this study is to compare the biomechanical properties of these three materials in terms of bending stiffness with a single static load and after cyclical loading, simulating physiologic wrist motion.

Materials and Methods

Three volar plating systems with fixed angle were tested: Zimmer stainless steel volar lateral column (Warsaw, IN); Hand Innovations titanium DVR (Miami, FL); Lima Corporate CF-PEEK DiPHOS-RM (San Daniele Del Friuli, Udine, Italy). For each type of plate tested four right synthetic composite bone radii were used. An unstable, extraarticular fracture was simulated by making an 8 mm gap with a saw starting 12 mm proximal to the articular surface of the radius on the distal radio-ulnar joint side. The osteotomies were made perpendicular to the long axis of the bone to allow for a consistent fracture gap on the dorsal and volar sides of the radius. Plates were implanted using all the distal and proximal fixation holes [Fig. 1]. Each synthetic radius model was potted in methylmethacrylate and tested in a bi-axial servo-hydraulic test frame (MTS Minibionix 858, universal testing machine) for load to failure by advancing a cobalt chrome sphere centered over the articular surface at a constant rate of displacement of 5 mm/min. The sphere was advanced until the construct failed or the dorsal edges of the fracture met. The resultant force was defined as bending stiffness pre fatigue. Three constructs for each plate were then dynamically loaded for 6000 cycles of fatigue at a frequency of 10Hz, with a load value corresponding to the 50% of the previously calculated bending strength. Finally, the constructs were loaded to failure, measuring the bending stiffness post fatigue.

Background

Patient specific instrumentation (PSI) for total knee replacement (TKR) has demonstrated mixed success in simplifying the operation, reducing its costs, and improving limb alignment. Evaluation of PSI with tools such as radiostereometric analysis (RSA) has been limited, especially for cut-through style guides providing mechanical alignment. The primary goal of the present study was to compare implant migration following TKR using conventional and PSI surgical techniques, with secondary goals to examine whether the use of PSI reduces operative time, instrumentation, and surgical waste.

Methods

The study was designed as a prospective, randomized controlled trial of 50 patients, with 25 patients each in the PSI and conventional groups, powered for the RSA analysis. Patients in the PSI group received an MRI and standing 3-foot x-rays to construct patient-specific cut-through surgical guides for the femur and tibia with a mechanical alignment. All patients received the same posterior-stabilized implant, with marker beads inserted in the bone around the implants to enable RSA imaging. Intraoperative variables such as time, number of instrumentation trays used, and mass of surgical waste were recorded. Patients underwent supine RSA exams at multiple time points (2&6 weeks, 3&6 months and yearly) with 6 months data currently available. Migration of the tibial and femoral components was calculated using model-based RSA software. WOMAC, SF-12, EQ5D, and UCLA outcome measures were recorded pre-operatively and post-operatively.

Background

Surgeons generally perform total knee replacement using either a gap balancing or measured resection approach. In gap balancing, ligamentous releases are performed first to create an equal joint space before any bony resections are performed. In measured resection, bony resections are performed first to match anatomical landmarks, and soft tissue releases are subsequently performed to balance the joint space. Previous studies have found a greater rate of coronal instability and femoral component lift-off using the measured resection technique, but it is unknown how potential differences in loading translate into component stability and fixation.

Methods

Patients were randomly assigned at the time of referral to a surgeon performing either the gap balancing or measured resection technique (n = 12 knees per group). Both groups received an identical cemented, posterior-stabilized implant. At the time of surgery, marker beads were inserted in the bone around the implants to enable radiostereometeric analysis (RSA) imaging. Patients underwent supine RSA exams at 0–2 weeks, 6 weeks, 3 months, 6 months, and 12 months. Migration of the tibial and femoral components including maximum total point motion (MTPM) was calculated using model-based RSA software. Knee Society Scores were also recorded for each group.

Introduction

Recently, tibial insert design of cruciate-substituting (CS) polyethylene insert is employed and widely used. However, in vivo kinematics of using CS polyethylene insert is still unclear. In this study, it is hypothesized that CS polyethylene insert leads to stability of femoro-tibial joint as well as posterior-stabilized (PS) polyethylene insert, even if PCL is sacrificed after TKA. The purpose of this study is an investigation of in vivo kinematics of femoro-tibial joint with use of CS polyethylene insert before and after PCL resction using computer assisted navigation system and tensor device intra-operatively in TKA.

Materials and Methods

Sixty-one consecutive patients who had knees of osteoarthritis with varus deformity were investigated in this study. All TKAs (Triathlon, Stryker) were performed using computer assisted navigation system. During surgery, using a tensor device, after bony cut of femur and tibia, joint gaps were assessed in 0 and 90 degrees in flexion. Then, CS polyethylene tibial trial insert were inserted after trial implantation of femoral and tibial components, before and after resection of PCL, respectively. The kinematic parameters of the soft-tissue balance, and amount of coronal and sagittal relative movement between femur and tibia were obtained by interpreting kinematics, which display tables throughout the range of motion (ROM) in the navigation system. In each ROM (30, 45, 60, 90, max degrees), the data were analyzed with a ANOVA test, and mean values were compared by the multiple comparison test (Turkey HSD test) (p< 0.05).

Introduction

Surgical planning for Patient Specific Instrumentation (PSI) in total knee arthroplasty (TKA) is based on static non-functional imaging (CT or MRI). Component alignment is determined prior to any assessment of clinical soft tissue laxity. This leads to surgical planning where assumptions of correctability of preoperative deformity are false and a need for intraoperative variation or abandonment of the PSI blocks occurs. The aim of this study is to determine whether functional radiology complements pre-surgical planning by identifying non-predictable patient variation in laxity.

Method

Pre-operative CT's, standing radiographs and functional radiographs assessing coronal laxity at 20° flexion were collected for 20 patients. Varus/valgus laxity was assessed using the TELOS stress device (TELOS GmbH, Marburg, Germany, see Figure 1). The varus/valgus load was incrementally increased to either a maximum load of 150N or until the patient could not tolerate the discomfort. Radiographs were taken whilst the knee was held in the stressed position.

CT scans were segmented and anatomical points landmarked. 2D–3D pose estimations were performed using the femur and tibia against the radiographs to determine knee alignment with each functional radiograph and so characterise the varus/valgus laxity

BACKGROUND

As the climate of medicine continues to change, physicians and healthcare administrations seek to improve both the quality of the care we provide patients, as well as reducing the cost at which we provide that care. Delivering value based care is of the utmost importance. The Perioperative Surgical Home (PSH) model is a multidisciplinary team approach to care that has shown success in reducing cost, length of stay, and admission to after care facilities. We sought to compare the results of total knee arthroplasty patients managed in the PSH rapid recovery model, to patients managed in a more traditional fashion.

METHODS

We compared 451 patients managed in the PSH model from January 1 to December 31, 2015 to 453 patients managed in a more traditional fashion from January 1 to December 31, 2014.

Introduction

Improvements in function after THA can be evaluated using validated health outcome surveys but studies have shown that PROMs are unreliable in following the progress of individuals. Formal gait lab analysis is expensive, time consuming and fixed in terms of location. Inertial Measurement Units (IMUs) containing accelerometers and gyroscopes can determine aspects of gait kinematics in a portable package and can be used in the outpatient setting (Figure 1). In this study multiple metrics describing gait were evaluated pre- and post THA and comparisons made with the normal population

Methods

The gait of 55 patients with monarthrodial hip arthrosis was measured pre-operatively and at one year post-surgery. Patients with medical co-morbidity or other condition affecting their gait were excluded. Six IMUs aligned in the sagittal plane were attached at the level of the anterior superior iliac spines, mid-thigh and mid-shank. Data was analysed using proprietary software (Figure 2). Each patient underwent a conventional THA using a posterolateral approach. An identical test was performed one year after surgery. 92 healthy individuals with a normal observed gait were used as controls.

INTRODUCTION

Patellofemoral compilcations are among the most frequently observed adverse events after total knee arthroplasty. The posterior location with Femoral component of conventional TKA in AP alignment cause paradoxical movement, but, guide motion TKA (Journey.2.BCS) with anterior post-cam remain a correct AP alignment. The purpose of this study was to investigate patellofemoral (PF) contact stress between Bi-Cruciate Substituting TKA (Journey.2.BCS) and CR TKA (Journey.CR).

METHODS

We evaluated 22 knees with medial compartment osteoarthritis who underwent. Simultaneous bilateral TKA. The prospective randomized study was to measure intraoperative PF contact stress by a patellofemoral sensor (Kyowa Co., Ltd., Tokyo, Japan) comparing the identical Bi-Cruciate Substituting or CR Journey.2 total knee prostheses implanted bilaterally in the same patient.

Background

Level 1 studies for fracture management of upper extremity fractures remains rare. The influence of these studies on management trends has yet to be evaluated. The purpose of this study was to examine alterations in national trends managing mid-shaft clavicle and intra-articular distal humerus fractures (DHF) surrounding recent Level 1 publications.

Methods

We retrospectively reviewed a comprehensive Medicare (2005–2012) and Humana (2007–2014) patient population database within the PearlDiver supercomputer (Warsaw, IN, USA) for DHF and mid-shaft clavicle fractures, respectively. Non-operative management and open reduction internal fixation (ORIF) were reviewed for mid-shaft clavicle fractures. ORIF and total elbow arthroplasty (TEA) were reviewed for DHF. Total use and annual utilization rates were investigated using age limits defined in the original Level 1 studies.

Background

Locked anterior shoulders (LAS) with static instability and anterior glenoid bone loss are challenging in the elderly population. Reverse shoulder arthroplasty (RSA) has been employed in treating these patients. No study has compared RSA for LAS to classically indicated RSA.

Methods

A case-control study of patients treated with RSA for LAS with glenoid bone loss and static instability was performed using matched controls treated with primary RSA for classic indications. Twenty-four cases and 48 controls were evaluated. Average follow-up was 25.5 months and median age was 76. Motion, outcome assessments, and postoperative radiographs were compared.

Introduction

Ambulation in the postoperative period following TKR is a marker of speed of recovery and, potentally, longer term outcomes. However, patient lifestyle factors are a major confounder. This study sought to develop a model of expected patient step count taking into account preoperative condition and demographics in order to benchmark recovery at a patient specific level.

Method

94 patients were recruited to the study. BMI, demographics, the Short Form 12 (SF-12) and the Knee injury and Osteoarthritis Outcome Score (KOOS) were all captured preoperatively. Step count was measured using commercially available Fitbit devices preoperatively, immediately postoperatively and at 6 weeks postoperatively. Stepwise multiple linear regression models were developed using the preoperative information to define a predictive model of the postoperative step count levels. Spearman's Rho correlations for all relevant data series were also calculated.

Background

Cup anteversion and inclination are important to avoid implant impingement and dislocation in total hip arthroplasty (THA). However, it is well known that functional cup anteversion and cup inclination also change as the pelvic sagittal inclination (PSI) changes, and many reports have been made to investigate the PSI in supine and standing positions. However, the maximum numbers of subjects studied are around 150 due to the requirement of considerable manual input in measuring the PSIs. Therefore, PSI in supine and standing positions were measured fully automatically with a computational method in a large cohort, and the factors which relate to the PSI change from supine to standing were analyzed in this study.

Methods

A total of 422 patients who underwent THA from 2011 to 2015 were the subjects of this study. There were 83 patients with primary OA, 274 patients with DDH derived secondary OA (DDH-OA), 48 patients with osteonecrosis, and 17 patients with rapidly destructive coxopathy (RDC). The median age of the patient was 61 (range; 15–87). Preoperative PSI in supine and standing positions were measured and the number of cases in which PSI changed more than 10° posteriorly were calculated. PSI in supine was measured as the angle between the anterior pelvic plane (APP) and the horizontal line of the body on the sagittal plane of APP, and PSI in standing was measured as the angle between the APP and the line perpendicular to the horizontal surface on the sagittal plane of APP (Fig. 1). The value was set positive if the pelvis was tilted anteriorly and was set negative if the pelvis tilted posteriorly. Type of hip disease, sex, and age were analyzed with multiple logistic regression analysis if they were related to PSI change of more than 10°. For accuracy verification, PSI in supine and standing were measured manually with the previous manual method in 100 cases and were compared with the automated system used in this study.

Introduction

There have been increased concerns with trunnion fretting and corrosion and adverse local tissue reactions (ALTR) in total hip arthroplasty. We report on 11 catastrophic trunnion failures associated with severe ALTR requiring urgent revision arthroplasty.

Methods

We retrospectively reviewed 10 patients with gross trunnion failure (n=11) and an additional 3 patients with impending trunnion failure.

INTRODUCTION

Successful clinical outcomes following unicompartmental knee arthroplasty (UKA) depend on component positioning, soft tissue balance and lower limb alignment, all of which can be difficult to achieve using manual instrumentation. A new robotic-guided technology has been shown to improve postoperative implant positioning and lower limb alignment in UKA but so far no studies have reported clinical results of robotic-assisted medial UKA. Goal of this study therefore was to assess outcomes of robotic-assisted medial UKA in a large cohort of patients at short-term follow-up.

METHODS

This multicenter study with IRB approval examines the survivorship and satisfaction of this robotic-assisted procedure coupled with an anatomically designed UKA implant at a minimum of two-year follow-up. A total of 1007 patients (1135 knees) underwent robotic-assisted surgery for a medial UKA from six surgeons at separate institutions in the United States. All patients received a fixed-bearing metal backed onlay implant as the tibial component between March 2009 and December 2011 (Figure 1). Each patient was contacted at minimum two-year follow-up and asked a series of five questions to determine implant survivorship and patient satisfaction. Survivorship analysis was performed using Kaplan-Meier method and worst-case scenario analysis was performed whereby all patients were considered as revision when they declined study participation. Revision rates were compared in younger and older patients (age cut-off 60 years) and in patients with different body mass index (body mass index cut-off 35 kg/m²). Two-sided chi-square tests were used to compare these groups.

INTRODUCTION

Medial and lateral unicompartmental knee arthroplasty (UKA) are both reliable treatment options for isolated osteoarthritis. Postoperative lower leg alignment is known to play an important role on short-term functional outcomes, which is an important argument for the use of robotic-assisted surgery. Since several anatomical and kinematic differences exist between both compartments, it seems inaccurate to aim for similar postoperative lower leg alignment in medial and lateral UKA. Purpose of this study was (I) to compare outcomes between both procedures and (II) to assess the role of preoperative and postoperative alignment on short-term outcomes in both procedures.

METHODS

Patients who underwent robotic-assisted medial or lateral UKA were included if they completed functional outcomes questionnaires preoperatively and postoperatively (Western Ontario and McMaster Universities Arthritis score) and completed an artificial joint awareness questionnaire (Forgotten Joint Score) postoperatively (not used preoperatively). A total of 143 medial UKA and 36 lateral UKA patients were included and mean follow-up was 2.4-years (range: 2.0 – 5.0 year). Postoperative alignment was measured using hip-knee-ankle radiographs with a standardized method. Alignment was categorized in medial and lateral UKA as undercorrection (3° to 7° varus or valgus, respectively), neutral (−1° to 3° varus or valgus, respectively), or overcorrection (3° to 7° valgus or varus, respectively). Outcomes were compared using independent t-tests and Pearson correlation analysis was performed to assess a correlation between alignment and outcomes.

INTRODUCTION

There is a growing interest in surgical variables that are controlled by the orthopaedic surgeon, including lower leg alignment and soft tissue balancing. Since more tight control over these factors is associated with improved outcomes of total knee arthroplasty (TKA), several computer navigation systems have been developed. Many meta-analyses showed that mechanical axis accuracy and component positioning are improved using computer navigation and one may therefore expect better outcomes with computer navigation but studies showing this are lacking. Therefore, a systematic review with meta-analysis was performed on studies comparing functional outcomes of computer-navigated and conventional TKA. Goals of this study were to (I) assess outcomes of computer-navigated versus conventional TKA and (II) to stratify these results by the surgical variables the systems aim to control.

METHODS

A systematic search in PubMed, Embase and Cochrane Library was performed for comparative studies reporting functional outcomes of computer-navigated versus conventional TKA. Knee Society Scores (KSS) Total were most often reported and studies reporting this outcome score were included. Outcomes of computer-navigated and conventional TKA were compared (I) in all studies and (II) stratified by navigation systems that only controlled for lower leg alignment or systems that controlled for lower leg alignment and soft tissue balancing. Level of evidence was determined using the adjusted Oxford Centre for Evidence-Based Medicine tool and methodological quality was assessed using Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) tool. Outcomes were reported in mean difference (MD) with 95% confidence intervals [Lower Bound 95%, Upper Bound 95%].

Introduction

Systemic metal ion monitoring (Co;Cr) has proven to be a useful screening tool for implant performance to detect failure at an early stage in metal-on-metal hip arthroplasty. Several clinical studies have reported elevated metal ion levels after total knee arthroplasty (TKA), with fairly high levels associated with rotating hinge knees (RHK) and megaprostheses¹. In a knee simulator study, Kretzer², demonstrated volumetric wear and corrosion of metallic surfaces. However, prospective in vivo data are scarce, resulting in a lack of knowledge of how levels evolve over time. The goal of this study was to measure serum Co and Cr levels in several types TKA patients prospectively, evaluate the evolution in time and investigate whether elevated levels could be used as an indicator for implant failure.

Patients and Methods

The study was conducted at Ghent University hospital. 130 patients undergoing knee arthroplasty were included in the study, 35 patients were lost due to logistic problems. 95 patients with 124 knee prostheses had received either a TKA (primary or revision) (69 in 55 patients), a unicompartimental knee arthroplasty (7 UKA), a RHK (revision −7 in 6 patients) or a megaprosthesis (malignant bone tumours − 28 in 27 patients) (Fig 1). The TKA, UKA and RHK groups were followed prospectively, with serum Co and Cr ions measured preoperatively, at 3,6 and 12 months postoperatively. In patients with a megaprosthesis, metal ions were measured at follow-up (cross-sectional study design).

Background

Total knee arthroplasty (TKA) is a proven and cost-effective treatment for osteoarthritis. Despite the good to excellent long-term results, some patients remain dissatisfied. Our study aimed at establishing a predictive model to aid patient selection and decision-making in TKA.

Methods

Using data from our prospective arthroplasty outcome database, 113 patients were included. Pre- and postoperatively, the patients completed 107 questions in 5 questionnaires: KOOS, OKS, PCS, EQ-5D and KSS. First, outcome parameters were compared between the satisfied and dissatisfied group. Secondly, we developed a new prediction tool using regression analysis. Each outcome score was analysed with simple regression. Subsequently, the predictive weight of individual questions was evaluated applying multiple linear regression. Finally, 10 questions were retained to construct a new prediction tool.

Introduction

Total hip arthroplasty (THA) is the most effective treatment modality for severe arthritis of the hip. Patients report excellent clinical and functional outcomes following THA, including subjective improvement in gait mechanics. However, few studies in the literature have outlined the impact of THA, as well as surgical approach, on gait kinetics and kinematics.

Purpose

The purpose of this study was to determine the impact of surgical approach for THA on quantitative gait analysis.

Background

The advent of highly cross-linked polyethylene has resulted in improved wear rates and reduced osteolysis with at least intermediate follow-up when compared to conventional polyethylene. However, the role of alternative femoral head bearing materials in decreasing wear is less clear. The purpose of this study was to determine in-vivo polyethylene wear rates across ceramic, Oxinium, and cobalt chrome femoral head articulations.

Methods

A review of our institutional database was performed to identify patients who underwent a total hip arthroplasty using either ceramic or oxidized zirconium (Oxinium) femoral head components on highly cross-linked polyethylene between 2008 and 2011. These patients were then matched on implant type, age, sex and BMI with patients who had a cobalt chrome bearing implant during the same time period. RSA analysis was performed using the center index method to measure femoral head penetration (polyethylene wear). Secondary quality of life outcomes were collected using WOMAC and HHS Scores. Paired analyses were performed to detect differences in wear rate (mm/year) between the cobalt chrome cohorts and their matched ceramic and Oxinium cohorts. Additional independent group comparisons were performed by analysis of variance with the control groups collapsed to determine wear rate differences between all three cohorts.

Background

The management of the patella during primary total knee arthroplasty (TKA) is controversial. Despite the majority of patients reporting excellent outcomes following TKA, a common complaint is anterior knee pain. Resurfacing of the patella at the time of initial surgery has been proposed as a means of preventing anterior knee pain, however current evidence, including four recent meta-analyses, has failed to show clear superiority of patellar resurfacing. Therefore, the purpose of this study was to estimate the cost-effectiveness of patellar resurfacing compared to non-resurfacing in TKA.

Methods

We conducted a cost-effectiveness analysis using a decision analytic model to represent a hypothetical patient cohort undergoing primary TKA. Each patient will receive a TKA either with the Patella Resurfaced or Not Resurfaced. Following surgery, patients can transition to one of three chronic health states: 1) Well Post-operative, 2) Patellofemoral Pain (PFP), or 3) Serious Adverse Event (AE), which we have defined as any event requiring Revision TKA, including: loosening/lysis, infection, instability, or fracture (Figure 1). We obtained revision rates following TKA for both resurfaced and unresurfaced cohorts using data from the 2014 Australian Registry. This data was chosen due to similarities between Australian and North American practice patterns and patient demographics, as well as the availability of longer term follow up data, up to 14 years postoperative. Our effectiveness outcome for the model was the quality-adjusted life year (QALY). We used utility scores obtained from the literature to calculate QALYs for each health state. Direct procedure costs were obtained from our institution's case costing department, and the billing fees for each procedure. We estimated cost-effectiveness from a Canadian publicly funded health care system perspective. All costs and quality of life outcomes were discounted at a rate of 5%. All costs are presented in 2015 Canadian dollars.

INTRODUCTION

Shoulder arthroplasty (SA) is an effective procedure for managing patients with shoulder pain secondary to degenerative joint disease or end stage arthritis that has failed conservative treatment. Insurance status has been shown to be an indicator of patient morbidity and mortality. The objective of the current study is to evaluate the effect of patient insurance status on outcomes following shoulder replacement surgery.

METHODS

Data was obtained from the Nationwide Inpatient Sample between 2004 and 2011. Analysis included patients undergoing shoulder arthroplasty procedures determined by ICD-9 procedure codes. Patient demographics and comorbidities were analyzed and stratified by insurance type. The primary outcome was medical and surgical complications occurring during the same hospitalization with secondary analysis of mortality. Pearson's chi¬squared test and multivariate regression were performed.

Introduction

Hip arthroplasty is one of the most common procedures performed every year however complications do occur. Prior studies have examined the impact of insurance status on complications after TJA in small or focused cohorts. The purpose of our study was to utilize a large all-payer inpatient healthcare database to evaluate the effect of patient insurance status on complications following hip arthroplasty.

Methods

Data was obtained from the Nationwide Inpatient Sample between 2004 and 2011. Analysis included patients undergoing hip arthroplasty procedures determined by ICD-9 procedure codes. Patient demographics and comorbidities were analyzed and stratified by insurance type. The primary outcome was medical complications, surgical complications and mortality during the same hospitalization. A secondary analysis was performed using a matched cohort comparing patients with Medicare vs private insurance using the coarsened exact matching algorithm. Pearson's chi-squared test and multivariate regression were performed.

Introduction

Knee arthroplasty is one of the most common inpatient surgeries procedures performed every year however complications do occur. Prior studies have examined the impact of insurance status on complications after TJA in small or focused cohorts. The purpose of our study was to utilize a large all-payer inpatient healthcare database to evaluate the effect of patient insurance status on complications following knee arthroplasty.

Methods

Data was obtained from the Nationwide Inpatient Sample between 2004 and 2011. Analysis included patients undergoing knee arthroplasty procedures determined by ICD-9 procedure codes. Patient demographics and comorbidities were analyzed and stratified by insurance type. The primary outcome was medical complications, surgical complications and mortality during the same hospitalization. A secondary analysis was performed using a matched cohort comparing patients with Medicare vs private insurance using the coarsened exact matching algorithm. Pearson's chi-squared test and multivariate regression were performed.

Introduction

A correct balancing of the knee following TKA surgery is believed to minimize instability and improve patient satisfaction. In that respect, trial components containing force sensors can be used. These force sensors provide insight in the medial/lateral force ratio as well as absolute contact forces. Although this method finds clinical application already, the target values for both the force magnitude and ratio under surgical conditions remain uncertain.

Methods

A total of eight non-arthritic cadaveric knees have been tested mimicking surgical conditions. Therefore, the specimens are mounted in a custom knee simulator (Verstraete et al., 2015). This simulator allows to test full lower limb specimens, providing kinematic freedom throughout the range of motion. Knee flexion is obtained by lifting the femur (thigh pull). Knee kinematics are simultaneously recorded by means of a navigation system and based on the mechanical axis of the femur and tibia.

In addition, the load transferred through the medial and lateral compartment of the knee is monitored. Therefore, a 2.4 mm thick sawing blade is used to machine a slot in the tibia perpendicular to the mechanical axis, at the location of the tibial cut in TKA surgery. A complete disconnection was thereby assured between the tibial plateau and the distal tibia. To fill the created gap, custom 3D printed shims were inserted (Fig. 1). Through their specific geometry, these shims create a load deviation between two pressure pads (Tekscan type 4011 sensor) seated on the medial and lateral side. Following the insertion of the shims, the knee was closed before performing the kinematic and kinetic tests.

Introduction

Current modeling techniques have been used to model the Reverse Total Shoulder Arthroplasty (RTSA) to account for the geometric changes implemented after RTSA [2,3]. Though these models have provided insight into the effects of geometric changes from RTSA these is still a limitation of understanding muscle function after RTSA on a patient-specific basis. The goal of this study sought to overcome this limitation by developing an approach to calibrate patient-specific muscle strength for an RTSA subject.

Methods

The approach was performed for both isometric 0° abduction and dynamic abduction. A 12 degree of freedom (DOF) model developed in our previous work was used in conjunction with our clinical data to create a set of patient-specific data (3 dimensional kinematics, muscle activations (), muscle moment arms, joint moments, muscle length, muscle velocity, tendon slack length (), optimal fiber length, peak isometric force)) that was used in a novel optimization scheme to estimate muscle parameters that correspond to the patient's muscle strength[4]. The optimization varied to minimize the difference between measured (“in vivo”) and predicted joint moments and measured (“in vivo”) and predicted muscle activations (). The predicted joint moments were constructed as a summation of muscle moments. The nested optimization was implemented within matlab (Mathworks). The optimization yields a set of muscle parameters that correspond to the subject's muscle strength. The abduction activity was optimized [4,5]. To validate the model we predicted dynamic joint moment and activation for the abduction activity (Figure 1).

INTRODUCTION

Most total knees today are CR or PS, with lateral and medial condyles similar in shape. There is excellent durability, but a shortfall in functional outcomes compared with normals, evidenced by abnormal contact points and gait kinematics, and paradoxical sliding. However unicondylar, medial pivot, or bicruciate retaining, are preferred by patients, ascribed to AP stability or retention of anatomic structures (Pritchett; Zuiderbaan). Recently, Guided Motion knees have been shown to more closely reproduce anatomic kinematics (Walker; Willing; Amiri; Lin; Zumbrunn). As a design approach we proposed Design Criteria: reproduce the function of each anatomic stabilizing structure with bearing surfaces on the lateral and medial sides and intercondylar; resected cruciates because this is surgically preferred; avoid a cam-post because of central femur bone removal, soft tissue entrapment, noises, and damage (Pritchett; Nunley). Our hypothesis was that these criteria could produce a Guided Motion design with normal kinematics.

METHODS & MATERIALS

Numerous studies on stability and laxity showed the ACL was essential to controlling posterior femoral displacement on the tibia whether the knee was loaded or unloaded. Under load, the anterior upwards slope of the medial tibial plateau prevented anterior displacement (Griffen; Freeman; Pinskerova; Reynolds). The posterior cruciate and the downward lateral tibial slope produced lateral rollback in flexion. The Replica Guided Motion knee had 3 bearings (Fig 1). The lateral side was shallow and sloped posteriorly, with a posterior lip to prevent excess displacement. The medial anterior tibial and femoral slopes were increased as in the anatomic knee. In the intercondylar region, a saddle bearing replaced ACL function by controlling posterior femoral displacement. For testing, a typical PS design was used as comparison. A Knee Test Machine (Fig 2) flexed the knee, and applied axial compression, shear and torque to represent a range of functions. Bone shapes were reproduced by 3D printing and collaterals by elastomeric bands. Motion was recorded with a digital camera, and Geomagic to process data.

INTRODUCTION

Ligament balancing aims to equalize lateral and medial gaps or tensions for optimal functional outcomes. Balancing can now be measured as lateral and medial contact forces during flexion (Roche 2014). Several studies found improved functional outcomes with balancing (Unitt 2008; Gustke 2014a; Gustke 2014b) although another study found only weak correlations (Meneghini 2016). Questions remain on study design, optimal lateral-medial force ratio, and remodeling over time. Our goals were to determine the functional outcomes between pre-op and 6 months post-op, and determine if there was a range of balancing parameters which gave the highest scores.

METHODS

This IRB study involved a single surgeon and the same CR implant (Triathlon). Fifty patients were enrolled age 50–90 years. A navigation system was used for alignments. Balancing aimed for equal lateral and medial contact forces throughout flexion, using various soft tissue releases (Meneghini 2013; Mihalko 2015). The patients completed a Knee Society evaluation pre-op, 4 weeks, 3 months and 6 months. The total (medial+lateral) force, and the medial/(medial+lateral) force ratio was calculated for 4 flexion angles and averaged. These were plotted against Pain, Satisfaction, Delta Function (postop – preop), and Delta Flexion Angle. The data was divided into 2 groups. 1. By balancing parameters. T-Test for differences in outcomes between the 2 groups. 2. By outcome parameters. T-Test for differences in Balancing Parameters between the two groups.

Background

More and more patients with end-stage knee OA are treated with total knee replacements (TKR). A modern TKR (Persona PS system, Zimmer Inc.) was designed with the hope to improve fit by providing additional sizing options on the femur and tibia. To date, there is very little information regarding the knee strength and knee mechanics during gait after the TKR. Furthermore, as a great percentage of knee OA patients have OA limited in one knee compartment and in the patellofemoral joint, a bi-compartmental knee replacement (BKR) (iDUO system, ConforMIS Inc.) was designed to treat OA at these affected areas. The BKR re-creates the individual's knee shape while correcting for any deformity. In addition, the BKR procedure results in less bone loss and retains the cruciate ligaments. To date, the influence of the BKR on knee strength and knee mechanics remains unknown. The purpose of the study was to evaluate knee strength and mechanics during level walking after the TKR and BKR surgeries.

Methods

Twelve healthy control participants (age=57±6 yr.; mass=82±11 kg; height=175±11 cm), eight patients (age=63±10 yr.; mass=87±20 kg; height=166±8 cm) with ten BKR systems (post-op time = 17±9 mo.), and nine patients (age=65±9 yr.; mass=90±35 kg; Height=169±12 cm) with twelve TKR systems (post-op time = 14±5 mo.) participated in the study. In a laboratory setting, maximal isometric knee strength was evaluated. Motion capture and 3D kinematic and kinetic analyses were conducted for level walking. One way ANOVA was used to determine differences among the BKR, TKR, and the healthy control knees.

Purpose

There is controversial whether synovectomy must be done in primary total knee arthroplasty (TKA). The objectivity of the study was to compare the effect of synovectomy on inflammation and clinical outcomes after surgical treatment of knee osteoarthritis.

Methods

A total of 240 patients who underwent primary unilateral TKR were randomly divided into a group without (Group A) and with synovectomy (Group B). All operations were performed by the same surgeon and follow-up was for 4 year. Clinical outcomes (including American Knee Society score (AKS), SF-36, and HSS scores) serum inflammatory markers (including interleukin-6 (IL-6), CRP and ESR) and the difference in temperature of the affected knee skin, swelling, ROM, patients VAS satisfaction score and VAS pain score were sequentially evaluated until 4 years after surgery.

Purpose

Previous studies have demonstrated pronounced reduction of sleep quality following major surgery, which may affect postoperative pain and early recovery. This prospective, randomized, controlled trial was designed to evaluate the effect of zolpidem on sleep quality in fast-track total knee arthroplasty (TKA).

Methods

180 patients who underwent primary TKA were enrolled in this study and randomized 1:1 to receive either zolpidem (Group A) or placebo (Group B) for 6 days. VAS pain scores (rest, ambulation, flexion, and night), range of motion (ROM), opioid analgesics use, postoperative nausea and vomiting (PONV) and other complication, sleep efficacy and patients VAS satisfaction were recorded postoperatively and at 1, 3, 5 after surgery. Sleep quality was measured using the polysomnography (PSG) and Epworth Sleepiness Scale.

Introduction

Corrosion of the femoral head-trunnion junction in modular hip components has become a concern as the corrosion products may lead to adverse local tissue reactions. A simple way to avoid trunnion corrosion is to manufacture the femoral head with a non-metallic material, such as ceramics that are widely. An alternative solution may lie in advanced polymers like polyaryletherketones (PAEKs). These thermoplastics have high mechanical strength necessary for use as femoral heads in hip arthroplasty, but they must be tested to ensure that they do not adversely affect the wear of the ultrahigh molecular weight polyethylene (UHMWPE) liner counterface. Pin-on-disc (POD) wear testing has been extensively used to evaluate the wear properties of UHMWPE prior to more extensive and costly analysis with joint simulators. We hypothesized that the wear of crosslinked UHMWPE would not be adversely affected in POD tests when articulated against an advanced thermoplastic counterface.

Methods

0.1 wt.% VitE blended UHMWPE stock was e-beam irradiated to 100, 125, 140, 160, and 175 kGy and machined into cylindrical pins for testing. An additional group of 100 kGy e-beam irradiated and melted UHMWPE (with no vitamin E) was also machined and tested.

Three different counterface materials were tested: (1) Cobalt-chrome (CoCr) with a surface roughness (R_a) of <0.5 μm, (2) Biolox™ ceramic (CeramTec), and (3) Polyetheretherketone (PEEK), a member of the PAEK family (Fig 1).

A bidirectional POD wear tester [1] was used to measure the wear rate of UHMWPE specimens, where the specimens moved in a 10 mm × 5 mm rectangular pattern under a Paul-type load curve [2] synchronized with the motion. The peak load of the loading curve corresponded to a peak contact pressure of 5.1 MPa between each UHMWPE pin specimen and the counterface disc. Each test was conducted at 2 Hz in undiluted bovine serum stabilized with ethylenediamine tetraacetate (EDTA) and penicillin. The pins were cleaned and weighed daily, and a wear rate was calculated at the end of each test by linear regression.

Introduction

While component malposition remains a major short and long term problem associated with total hip arthroplasty, enhanced technologies such as navigation and robotics have not yet been widely adopted. Both expense and increased OR time can be obstacles to adoption. The current study assesses the effect of the use of a smart mechanical navigation system on surgery time in total hip arthroplasty.

Patients and Methods

514 consecutive primary total hip arthroplasties were performed by a single surgeon from January 1, 2015 through March 31, 2016. Of these, 40 were performed using a smart mechanical navigation system (the HipXpert System, Surgical Planning Associates Inc., Boston, Massachusetts) and 474 were performed without navigation. The patients were not randomized. Incision to closure time (surgery time) was recorded for each procedure. A two tailed t-test was performed to assess statistical significance.

INTRODUCTION

The purpose of TKA is to restore normal kinematics and functioning to diseased knees. The purpose of this study was to determine whether intraoperative kinematic data are correlated with minimum one-year outcomes following primary TKA.

METHODS

We reviewed data on 185 consecutive primary TKAs in which sensor-embedded tibial trials were used to evaluate kinematic patterns following traditional ligament balancing. Procedures were performed by two board-certified arthroplasty surgeons. The same implant design and surgical approach was used for all knees.

Contact locations on the medial and lateral condyles were recorded for each patient at 0°, 45° and 90° of flexion, and full flexion. Vector equations were created by contact locations on the medial and lateral sides and the vector intersections determined the center of rotation between each measurement position. Center of rotation was calculated as the average of vector intersections at 0 to 45°, 45 to 90°, and 90° to full flexion. If the average center of rotation was between 16 and 1000 mm of the contact location on the medial side it was considered a medial pivot knee. Knees were also classified as medial (16 to 200 mm on medial side), lateral (16 to 200 mm on lateral side), translating (> 200 mm medially or laterally), and other (< 16 mm on both medial and lateral sides). The new Knee Society Scoring System (KSSO objective score, KSSS satisfaction score, KSSF function score), the EQ-5D™ Health Status Index, and the University of California Los Angeles (UCLA) Activity Level Score were measured preoperatively and at minimum one-year follow-up (average 20.4 months).

Introduction

Reports cite up to 20% of total knee arthroplasty (TKA) patients are not satisfied. Recent focus on alignment and balance has perhaps overshadowed kinematics as a key determinant of outcomes. Some propose that reproducing the native knee kinematics of lateral-pivot motion in early flexion during walking will enact optimal TKA outcomes. The purpose of this study was to determine if intra-operative kinematic patterns correlate with patient function, pain and satisfaction after TKA.

Methods

A retrospective review of consecutive TKA's performed by two surgeons was performed. After final components were implanted and balanced, sensor-embedded tibial trials were inserted and kinematic patterns were recorded through range-of-motion. Femoro-tibial contact points were recorded at four distinct flexion points (0°, 45°, 90° and full flexion). Center of rotation kinematic patterns were calculated and categorized as medial pivot, lateral pivot or translation at each measurement range via established criteria. Knees with lateral (L) pivot in early flexion between 0 and 45 ° and medial (M) pivot beyond 90°, regardless of the mid-flexion pivot pattern, formed the experimental group designated as LXM. All other patterns were designated non-LXM and formed the control group. Modern, validated clinical outcome measures (Knee Society Score, EQ5D, UCLA) were obtained preoperatively and at minimum one-year postoperatively.

Background

The direct anterior approach (DAA) for total hip arthroplasty (THA) is marketed with claims of superiority over other approaches. Femoral exposure can be technically challenging and potentially lead to early failure. We examined whether surgical approach is associated with early THA failure.

Methods

A retrospective review of 478 consecutive early revision THAs within five years of primary THA at three academic centers from 2011 through 2014 was performed. Exclusion criteria resulted in a final analysis sample of 341 early failure THAs. Primary surgical approach was documented for each revision, along with time to revision, and failure etiology.

Introduction

The effect of each step of medial soft tissue releases on the external rotation angle of the femoral component was assessed during posterior stabilized total knee arthroplasty (PS-TKA) with modified gap control technique.

Methods

Consecutive 840 knees were assessed. During PS-TKA, medial soft tissue release was done to obtain rectangular gap in extension using tensors/balancers. The deep fiber of medial collateral ligament (MCL) was released in all cases. No more release was done in 464 knees. Only anterior fiber of superficial MCL was released in 49 knees, and only posterior fiber of superficial MCL was released in 129 knees. Both fibers were released in 169 knees. Additional pes anserinus was released in 29 knees. Rotation angle of the femoral component was decided based on the flexion gap angle. The angle was compared among the five groups.

Introduction

Mid-flexion stability after total knee arthroplasty (TKA) is dependent, in large part, on implant design. Design variables include retention or sacrifice of the posterior cruciate ligament, conformity of the polyethylene tibial surface, and radius of curvature of the femoral component. In this study, we attempted to isolate the impact of femoral component design by comparing a single-radius design (SR) to a J-Curve design (JC). We selected cruciate-retaining implants to eliminate the effect of a cam-and-post mechanism. Mid-flexion performance these two designs were compared using the Lower-Quarter Y-Balance Test (YBT-LQ), as well as patient reported outcomes and measures of physical performance. The YBT-LQ is a simple functional test of unilateral lower extremity strength and balance. Reach of the contralateral limb is measured in three different directions (Figures 1–3). Our hypothesis was that the SR design would provide superior mid-flexion stability, and therefore, a greater reach distance in the YBT-LQ when compared to the JC group.

Methods

Patients undergoing primary, unilateral TKA were prospectively enrolled and block randomized to receive either the SR (n=30) or JC (n=30) implant. All surgeries were performed by one surgeon using a gap-balancing technique with a cruciate-retaining implant design. Patients completed outcome measures (KOOS, KSS, UCLA Activity), performed the YBT-LQ, and completed physical performance measures (walking speed, timed up-and-go, sit-to-stand) before surgery and 1 year postoperatively. A series of 2×2 repeated measures ANOVAS (Implant group x Time) were completed.

Introduction

Decreasing tissue damage and recovery time, while improving quality of life have been the focus of many approaches to total hip arthroplasty (THA). In this study, we compared two approaches, a tissue-sparing superior capsulotomy percutaneously assisted approach (SP) and the traditional posterior approach (TR), to address the question of whether the novel technique reduces tissue damage. The secondary aim of this study focused on the measurement technologies utilized to quantify the damage resulting from either SP or TR. Image J, BioQuant, and cellSens were the image analysis programs employed. Statistical validation and comparisons of results between all platforms were performed.

Methods

Both hips of freshly frozen cadaveric specimens (n = 8) were surgically prepared for THA with random procedure performed on left or right hip. All selected specimens had no prior implantation of devices to ensure all observed muscle damage occurred from the surgical technique. Surgeons resected tissue and performed necessary procedural steps up to device implantation. No devices were implanted during the study, as the aim was to quantify the damage caused by the incision and resection. After completion of the surgery, an independent surgeon (IS), who was blinded as to which method was performed on the specimen, excised the muscles and inspected areas of interest Assessment of the tissue damage was executed using a midsubstance cross-sectional area technique, validated by prior studies. High-resolution images of demarcated muscles were used for quantitative analysis. Three blinded independent reviewers quantified damaged tissue. The results were used to detect if statistically significant differences were present between the two methods. Furthermore, an independent reviewer using SPSS statistical software also assessed inter-program and inter-rater reliability.

Introduction

In total knee arthroplasty (TKA), non-cemented implants rely on initial fixation to stabilize the implant in order to facilitate biologic fixation. The initial fixation can be affected by several different factors from type of implant surface, implant design, patient factors, and surgical technique. The initial fixation is traditionally quantified by measuring the motion between the implant and underlying bone during loading (micromotion). Extraction force has also been quantified for cementless devices. The question remains does an increase or decrease in extraction force affect micromotion based on the fact that most loading at the knee joint is in compression. The objective of this research is to investigate if there is any correlation between extraction force and implant micromotion.

Methods

The relationship between extraction force and micromotion was evaluated by performing a series of experiments using a synthetic bone analog and a tibial baseplate with hexagon pegs. Tunnels for the hexagon pegs were machined into the synthetic bone analog with different diameters, from 9.7 to 11.7 mm. The smaller diameter tunnels increase the press fit between the peg and bone.

Sixty-six implants were tested to determine maximum extraction force. The implants were extracted using an electro-mechanical testing frame at a rate of 0.4 inches / minute. Two different types of bone analogs were used for this evaluation. One was an open-cell foam with a density of 12.5 lb/ft³ and the other was a closed-cell foam with a density of 20 lb/ft³.

Twelve TKA implants were tested to determine the maximum anterior-lift off micromotion during a posterior load application. A posterior stabilized polyethylene insert and mating femoral component were used during the loading. The posterior load cycled from 90 to 900 N for 500 cycles. The micromotion was evaluated with the femur at 90 degrees of flexion. Differential Variable Reluctance Transducers (DVRTs) were located under the four corners of the implant to quantify the superior-inferior motion of the implant. A composite synthetic bone analog was used for this evaluation, with open-cell foam (12.5 lb/ft³) on the inside and closed-cell foam (50 lb/ft³) on the outside.

Introduction

Shoulder arthroplasty is used to treat several common pathologies of the shoulder, including osteoarthritis, post-traumatic arthritis, and avascular necrosis. In replacement of the humeral head, modular components allow for anatomical variations, including retroversion angle and head-neck angle. Surgical options include an anatomic cut or a guide-assisted cut at a fixed retroversion and head-neck angle, which can vary the dimensions of the cut humeral head (height, anteroposterior (AP), and superoinferior (SI) diameters) and lead to negative long term clinical results. This study measures the effect of guide-assisted osteotomies on humeral head dimensions compared to anatomic dimensions.

Methods

Computed tomography (CT) scans from 20 cadaveric shoulder specimens (10 male, 10 female; 10 left) were converted to three-dimensional models using medical imaging software. An anatomic humeral head cut plane was placed at the anatomic head – neck junction of all shoulders by a fellowship trained shoulder surgeon. Cut planes were generated for each of the standard implant head-neck angles (125°, 130°, 135°, and 140°) and retroversion angles (20°, 30°, and 40°) in commercial cutting guides. Each cut plane was positioned to favour the anterior humeral head-neck junction while preserving the posterior cuff insertion. The humeral head height and diameter were measured in both the AP plane and the SI plane for the anatomic and guide-assisted osteotomy planes. Differences were compared using separate two-way repeated measures ANOVA for each dependent variable and deviations were shown using box plot and whisker diagrams.

Background

Humeral version is the twist angle of the humeral head relative to the distal humerus. Pre-operatively, it is most commonly measured referencing the transepicondylar axis, although various techniques are described in literature (Matsumura et al. 2014, Edelson 1999, Boileau et al., 2008). Accurate estimation of the version angle is important for humeral head osteotomy in preparation for shoulder arthroplasty, as deviations from native version can result in prosthesis malalignment. Most humeral head osteotomy guides instruct the surgeon to reference the ulnar axis with the elbow flexed at 90°. Average version values have been reported at 17.6° relative to the transepicondylar axis and 28.8° relative to the ulnar axis (Hernigou, Duparc, and Hernigou 2014), although it is highly variable and has been reported to range from 10° to 55° (Pearl and Volk 1999). These studies used 2D CT images; however, 2D has been shown to be unreliable for many glenohumeral measurements (Terrier 2015, Jacxsens 2015, Budge 2011). Three-dimensional (3D) modeling is now widely available and may improve the accuracy of version measurements. This study evaluated the effects of sex and measurement system on 3D version measurements made using the transepicondylar and ulnar axis methods, and additionally a flexion-extension axis commonly used in biomechanics.

Methods

Computed tomography (CT) scans of 51 cadaveric shoulders (26 male, 25 female; 32 left) were converted to 3D models using medical imaging software. The ulna was reduced to 90° flexion to replicate the arm position during intra-operative version measurement. Geometry was extracted to determine landmarks and co-ordinate systems for the humeral long axis, epicondylar axis, flexion-extension axis (centered through the capitellum and trochlear groove), and ulnar long axis. An anatomic humeral head cut plane was placed at the head-neck junction of all shoulders by a fellowship trained shoulder surgeon. Retroversion was measured with custom Matlab code that analysed the humeral head cut plane relative to a reference system based on the long axis of the humerus and each elbow axis. Effects of measurement systems were analyzed using separate 1-way RM ANOVAs for males and females. Sex differences were analyzed using unpaired t-tests for each measurement system.

Introduction

Several studies have shown that functional outcomes are similar regardless of being discharged directly to home or to a rehabilitation center after total knee arthroplasty (TKA). Therefore, we sought to determine if there is a difference in patient care or patient satisfaction for patients discharged to in-patient rehabilitation or home-based rehabilitation.

Materials and Methods

Between February and May of 2015, one hundred and seventy one consecutive patients were prospective identified after undergoing TKA by one of three surgeons. At an average of six-weeks post TKA, all patients were asked a patient administered questionnaire to determine if diagnostic testing (ultrasounds, or x-rays) or blood transfusions were performed during the first-six weeks at either home (n=86) or a rehab (n=85) facility.

Introduction

The advent of ambulatory total joint replacements has called for measures to reduce postoperative length of stay, while improving patient function and postoperative satisfaction. This prospective, randomized trial evaluated the efficacy of one-on-one preoperative physical therapy (PT) education with a supplemental web-based PT web-portal on discharge disposition, postoperative function and patient satisfaction after total joint replacement.

Materials & Methods

Between February and June 2015, 126 patients underwent unilateral total knee (n=63) or total hip arthroplasty (n=63). All patients attended a group preoperative education (preopEd) class [standard of care] and were subsequently randomized into two groups. One group received no further education as per the standard of care [control; TKA= 31; THA=32] and the other received an in-person one-on-one preoperative PT education session (preopPTEd) as well as access to a web-portal during the postoperative period [experimental; TKA=32; THA=31]. Discharge disposition was attained from hospital records. Patient satisfaction and WOMAC scores were evaluated by a series of patient administered questionnaires.

Introduction

Lewinnek's Safe-Zone gives recommendations only for cup placement in total hip arthroplasty while the orientation of the neck isn't considered. Furthermore the criteria for cup placement are not clearly defined and the ranges for cup orientation are considerably large. This study introduces new recommandations for the combined placement of both total hip components, when both, cup and stem, are considered. This defines the new dynamic combined safe-zone (cSafe-Zone) which gives clear directions for the optimal combined orientation of both components in order to maximize the intended range of movement (iROM) while reducing the risk for prosthetic impingement and dislocation.

Material and Methods

The combined safe-zone outlines the area that encloses all component orientations that achieve the predefined iROM without prosthetic impingement. A computerized 3D-model of a total hip prosthesis was established that does systematically test all design parameters semi-automatically in order to identify those component positions that fulfill the predefined conditions. The analysis was carried out for straight stems, anatomic stems and short stems. The iROM is composed of basic movements like flexion/extension, internal/external rotation, ab/adduction and combination of these movements that the patient should reach and that are commonly accepted as physiologic hip movements. The orientation of the cup was varied between 20° and 70° of inclination and −10° of retro- to 40° anteversion. Stem antetorsion was tested from −10° retro- to 40°-antetorsion and CCD-angle from 110° to 150°. Head-size and head/neck ratio were additional parameters.

Introduction

Hemiarthroplasty is a treatment option for comminuted fractures and non-unions of the distal humerus. Unfortunately, the poor anatomical fit of off-the-shelf distal humeral hemiarthroplasty (DHH) implants can cause altered cartilage contact mechanics. The result is reduced contact area and higher cartilage stresses, thus subsequent cartilage erosion a concern. Previous studies have investigated reverse-engineered DHH implants which reproduce the shape of the distal humerus bone or cartilage at the articulation, but still failed to match native contact mechanics. In this study, design optimization was used to determine the optimal DHH implant shape. We hypothesized that patient-specific optimal implants will outperform population-optimized designs, and both will optimize simple reverse-engineered designs.

Methods

The boney geometries of six elbow joints were created based on cadaver arm CT data using a semi-automatic threshold technique in 3D Slicer. CT scans were also obtained with the elbows denuded and disarticulated, such that the high contrast between hydrated cartilage and air could be exploited in order to reconstruct cartilage geometry. Using this 3D model data, finite element contact models were created for each elbow, where bones (distal humerus, proximal ulna and radius) were modelled as rigid surfaces covered by non-uniform thickness layers of cartilage. Cartilage was modelled as a Neo-Hookean hyperelastic material (K = 0.31 MPa, G = 0.37 MPa), and frictionless contact was assumed. In order to simulate hemiarthroplasty, the distal humerus cartilage surface was replaced by either a rigid surface in the shape of the subchondral bone (bone reverse engineered or BRE design), or a surface offset from the bone by some distance, which was defined parametrically and modified by an optimization algorithm. Simple flexion-extension with constant balanced muscle loads was simulated in ABAQUS (Fig 1), and resulting contact areas and contact stresses were calculated. For each specimen, the contact mechanics of the intact and DHH reconstructed joints were calculated. A design optimization algorithm in Matlab was used to determine the optimal offset distance which resulted in contact stress distributions on the ulna and radius which most closely resembled their intact conditions. This procedure was repeated in order to generate specimen-optimal offsets, as well as population-optimal offsets.

Introduction

The intrinsic constraint of a total knee replacement (TKR) implant system is considered an important characteristic which plays a large role in determining stability following surgery. Established techniques for evaluating the constraint of TKR implants, as described in ASTM F 1223-14, do not necessarily map directly to physiologically relevant loading scenarios where instability can occur, and thus give an incomplete picture of the constraint characteristics of a candidate implant design. Sophisticated joint motion simulators now allow for more physiologically representative joint loading (eg. gait), including the contributions of virtual soft tissues. In this study, we employ a function-based constraint measurement technique for evaluating the kinematics of two TKR designs during gait. Furthermore, we employ simulated soft tissues in order to create three “virtual” knees on which the TKR are tested.

Methods

The constraint characteristics of TKR implants were evaluated using a function-based measurement technique on a VIVO joint motion simulator (AMTI, Waltham, MA). The AVG75 standardized load and motion profiles for gait (Bergmann et al. 2014), were applied to an ultra-congruent cruciate-sacrificing TKR (Zimmer-Biomet, Warsaw, IN). Ligaments were simulated as point-to-point spring elements between the femur and tibia (3 bundles for MCL, 3 bundles for LCL). Ligament bundle origin, insertion, stiffness, and resting length properties were adapted from the publically available MB Knee project (simtk.org/home/mb_knee) to create three knees. AP and IE kinematics were recorded during simulated gait after approximately 500 “learning” cycles at 0.75 Hz. Trials were then repeated with superimposed AP forces or IE torques. The amount of superimposed load varied with the amount of compressive load, such that the superimposed load was ±25 N AP force or ±1 Nm IE torque, per 1000 N of compressive force. AP and IE laxities were calculated based on changes in AP and IE motions, respectively (Fig 1). Experiments were repeated with a second TKR design; using the same femoral component but replacing the ultra-congruent UHMWPE bearing with a 3D printed ABS plastic bearing featuring a less congruent sagittal profile. In total, there were 2 implants × 3 virtual knees × 5 simulated loading profiles = 30 different simulated gait trials.

Introduction

Preservation of the anterior cruciate ligament (ACL), along with the posterior cruciate ligament, is believed to improve functional outcomes in total knee replacement (TKR). The purpose of this study was to examine gait differences and muscle activation levels between ACL sacrificing (ACL-S) and bicruciate retaining (BCR) TKR subjects during level walking, downhill walking, and stair climbing.

Methods

Ten ACL-S (Vanguard CR) (69±8 yrs, 28.7±4.7 kg/m2) and eleven BCR (Vanguard XP, Zimmer-Biomet) (63±11 yrs, 31.0±7.6 kg/m2) subjects participated in this IRB approved study. Except for the condition of the ACL, both TKR designs were similar. Subjects were tested 8–14 months post-op in a motion analysis lab using a point cluster marker set and surface electrodes applied to the Vastus Medialis Oblique (VMO), Rectus Femoris (RF), Biceps Femoris (BF) and Semitendinosus (ST). 3D motion and force data and electromyography (EMG) data were collected simultaneously. Subjects were instructed to walk at a comfortable walking speed across a walkway, down a 12.5% downhill slope, and up a staircase. Five trials per activity were collected. Knee kinematics and kinetics were analyzed using BioMove (Stanford, Stanford, CA). The EMG dataset underwent full-wave rectification and was smoothed using a 300ms RMS window. Gait cycle was time normalized to 100%; relative voluntary contraction (RVC) was calculated by dividing the average activation during downhill walking by the maximum EMG value during level walking and multiplying by 100%.

Introduction

There is interest in minimally invasive solutions that reduce osteoarthritic symptoms and restore joint mobility in the early stages of cartilage degeneration or damage. The aim of the present study was to evaluate the Biolox®delta alumina-zirconia composite as a counterface for articulation against live cartilage in comparison to the clinically relevant CoCrMo alloy using a highly controlled in vitro ball-on-flat articulation bioreactor that has been shown to rank materials in accord with clinical experience.

Methods

The four-station bioreactor was housed in an incubator. The dual axis concept of this simulator approximates the rolling-gliding kinematics of the joint. Twelve 32 mm alumina-zirconia composite femoral heads (Biolox®delta, CeramTec GmbH, Germany) and twelve 32 mm CoCrMo femoral heads (Peter Brehm GmbH, Germany) made up the testing groups. Each head articulated against a cartilage disk of 14 mm diam., harvested from six months old steers. Free-swelling control disks were obtained as well. Testing was conducted in Mini ITS medium for three hours daily over 10 days applying a load of 40 N (∼2 MPa). PG/GAG was determined using the dimethylmethylene blue (DMMB) assay. Hydroxyproline was analyzed by high performance liquid chromatography coupled to a mass spectrometer. Additionally, at test conclusion, chondrocyte survival was determined using Live/Dead assay. Histological analysis was performed using a modified Mankin score. The effect of articulating material (ceramic, CoCrMo) on the various outputs of interest was evaluated using ANOVA. Blocking was performed with respect to the animals. The Mankin scores were compared using the Kruskal–Wallis test.

Background

Percutaneous endoscopic interlaminar discectomy (PEID) has achieved favorable effects in the treatment of lumbar disc herniation (LDH), as a new surgical procedure. With its wide range of applications, a series of complications related to the operation has gradually emerged.

Objective

To describe the type, incidence and characteristics of the complications following PEID and to explore preventative and treatment measures.

Introduction

Pelvic posterior tilt change (PPTC) after THA is caused by release of joint contracture and degenerative lumbar kyphosis. PPTC increases cup anteversion and inclination and results in a risk of prosthesis impingement (PI) and edge loading (EL). There was reportedly no component orientation of fixed bearing which can avoid PI and EL against 20°PPTC. However, dual mobility bearing (DM) has been reported to have a large oscillation angle and potential to withstand EL without increasing polyethylene (PE) wear against high cup inclination such as 60∼65°.

Objective

The purpose of this study was to investigate the optimal orientation of DM-THA for avoiding PI and EL against postoperative 20°PPTC.

Purpose

To achieve 3D kinematic analysis of total knee arthroplasty (TKA), 2D/3D registration techniques, which use X-ray fluoroscopic images and computer aided design model of the knee implants, have been applied to clinical cases. However, most conventional methods have needed time-consuming and labor-intensive manual operations in some process. In particular, for the 3D pose estimation of tibial component model from X-ray images, these manual operations were carefully performed because the pose estimation of symmetrical tibial component get severe local minima rather than that of unsymmetrical femoral component. In this study, therefore, we propose an automated 3D kinematic estimation method of tibial component based on statistical motion model, which is created from previous analyzed 3D kinematic data of TKA.

Methods

The used 2D/3D registration technique is based on a robust feature-based (contour-based) algorithm. In our proposed method, a statistical motion model which represents average and variability of joint motion is incorporated into the robust feature-based algorithm, particularly for the pose estimation of tibial component. The statistical motion model is created from previous a lot of analyzed 3D kinematic data of TKA. In this study, a statistical motion model for relative knee motion of the tibial component with respect to the femoral component was created and utilized. Fig. 1 shows each relative knee motion model for six degree of freedom (three translations and three rotations parameter). Thus, after the pose estimation of the femoral component model, 3D pose of the tibial component model is determined by maximum a posteriori (MAP) estimation using the new cost function introduced the statistical motion model.

Introduction

In hip arthroplasty, it has been shown that assembly of the femoral head onto the stem remains a non-standardized practice and differs between surgeons [1]. Pennock et al. determined by altering mechanical conditions during seating there was a direct effect on the taper strength [2]. Furthermore, Mali et al. demonstrated that components assembled with a lower assembly load had increased fretting currents and micromotion at the taper junction during cyclic testing [3]. This suggests overall performance may be affected by head assembly method. The purpose of this test was to perform controlled bench top studies to determine the influence of impaction force and compliance of support structure (or damping) on the initial stability of the taper junction.

Materials and Methods

Background

The clinical results of total hip arthroplasty (THA) with a cementless prosthesis have been constantly improving due to progress in the area of stem design and surface finish. However, majority of stems are well-fixed with canal filling or diaphyseal fit, and cortical hypertrophy or metaphyseal bone atrophy has been often observed. Cementless Spotorno stem (CLS stem; Zimmer, Warsaw, USA) is a double-tapered rectangular straight stem. The purpose of this study is to investigate the mean 13 years' results of CLS stem and to evaluate the press-fit stability of CLS stem.

Methods

Between 1999 and 2004, we treated 134 patients (142 hips) with CLS stem. Of those patients, 86 females (92 hips) and 13 males (14 hips), in total 99 patients (106 hips) were available at minimum of 11 years after surgery. At the time of follow-up, six females and five males were dead. The follow-up rate was 82% and the mean follow-up period was 13 years (SD; 20, range; 11–16). The mean age at the time of surgery was 65 years (SD; 10, range; 38–86). The mean body mass index was 24 (SD; 1.8, range; 19 to 28). Preoperative diagnoses were osteoarthritis in 92 patients, osteonecrosis in five patients, and rheumatoid arthritis in two patients. Majority of the patients were female because 84 patients of osteoarthritis suffered from hip dysplasia. For cementless acetabular reconstruction, APR cups (Zimmer, Warsaw, USA) were implanted in 10 hips, IOP cups (Zimmer, Warsaw, USA) in 22 hips, and Converge cups (Zimmer, Warsaw, USA) in 74 hips. As the liner of acetabular component, conventional UHMWPE (Sulene: Zimmer, Warsaw, USA) was used in APR cup and highly crosslinked UHMWPE (Durasul: Zimmer, Warsaw, USA) in IOP and Converge cups. The lipped liner was chosen in all cases, and lipped lesion was placed posteriorly. The radiographic stability of the femoral stem was determined by Engh's criteria. The ascertained period of spot welds was noted by Gruen zones on the femoral side. The presence of stress shielding, and subsidence was also evaluated.

Introduction

The KneeAlign2 (OrthAlign, Inc., Aliso Viejo, CA) is a portable accelerometer-based navigation device for use in performing the distal femoral resection in total knee arthroplasty (TKA). This device works as a computer-assisted surgical system. It does not require the use of a large console for registration and alignment feedback.(image1,2)

Purpose

The aim of this study was to investigate the accuracy in positioning the femoral component and the presense of a learning curve in conducting TKA using this device.

Background

Total knee prostheses are continually being redesigned to improve performance, longevity and closer mimic kinematics of the native knee. Despite continued improvements, all knee implants even those with proven design features, have failures. We identified a cohort of patients with isolated tibial component failures that occurred in a popular and successful knee system. Our purpose was to (1) characterize the observed radiographic failure pattern; (2) investigate the biologic response that may contribute to the failure; and (3) to determine if the failure mechanism was of a biological or a mechanical nature.

Methods

Twenty-one knees from 19 patients met the inclusion criteria of having isolated tibial component failure in a commonly used knee implant system. Radiographs from the primary and revision knee surgery were analyzed for implant positioning and failure pattern, respectively. Inflammatory biomarkers IL-1β, IL-6 and TNF-α were available in 16/21 knees and peripheral CD14⁺/16⁺ monocytes were measured in 10 of the above mentioned 16 knee revisions. Additionally, white blood cell (WBC) count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) were measured to rule out infection as the cause of the cytokine upregulation.

Background

A cell-based tissue-engineered construct can be employed for treating meniscal lesions occurring in the non-vascularized inner two-thirds. The objective of this study was to test the hypothesis that both pre-differentiation of human bone marrow derived stromal cells (hBMSCs) into chondrogenic lineage before cell seeding and platelet-rich plasma (PRP) pretreatment on a PLGA mesh scaffold enhances the healing capacity of the meniscus with hBMSCs-seeded scaffolds in vivo.

Methods

PRP of 5 donors was mixed and used for the experiments. The woven PLGA mesh scaffold (VicrylTM, Ethicon) measuring 20×8 mm (thickness, 0.2 mm) was prepared. The scaffolds were immersed into 1,000 μl of PRP and were centrifuged at 150g for 10 min. Then, the scaffold was flipped 180° and the same procedure was done for the other side. After washing, the scaffolds were soaked into 1,000 μl of DMEM media. hBMSCs from an iliac crest of 10 patients after informed consent and approval of our IRB were induced into chondrogenic differentiation with chondrogenic media containing 10 ng/ml rhTGF-ß3 in 1.2% alginate bead culture system for 7 days. Then, 2×10⁵ hBMSCs were recovered, seeded onto the scaffold, and cultured under dynamic condition. Based on the presence of pre-differentiation into chondrogenic lineage and the PRP pretreatment, 4 study groups were prepared. (no differentiation without PRP, no differentiation with PRP, chondrogenic differentiation without PRP, chondrogenic differentiation with PRP) Cell number for each cell-seeded scaffold was determined at 24 hours after seeding. Then, scaffolds were placed between human meniscal discs and were implanted subcutaneously in nude mice for 6 weeks (n=10 per group).

Background

Open-wedge high tibial osteotomy (OWHTO) is an operation involving proper load re-distribution in the treatment for medial uni-compartmental arthritis of the knee joint. Therefore, stable fixation is mandatory for safe healing of this additive type of osteotomy to minimize the risk of non-union and loss of correction. For stability, screws provide optimal support and anchorage of the fixator in the condylar area without risking penetration of either the articulating surface. The purpose of the study was to evaluate the screw insertion angle and orientation with an anatomical plate that is post-contoured to the surface geometry of the proximal tibia after OWHTO.

Methods

From March 2012 to June 2014, 31 uni-planar and 38 bi-planar osteotomies were evaluated. Postoperative computed tomography data obtained after open wedge high tibial osteotomy using a locking plate were used for reconstruction of the 3 dimensional model with Mimics v.16.0 of the proximal tibia and locking plate. Measurement data were compared between 2 groups (gap lesser than or equal to 10 mm (Group 1) and gap greater than 10 mm(Group 2)). These data were also compared between the uniplanar (Group 3) and bi-planar (Group 4) osteotomy groups.

Introduction

The use of open wedge high tibial osteotomy (OWHTO) to reduce knee pain by transferring weight-bearing loads to the relatively unaffected lateral compartment in varus knees and to delay the need for a knee replacement by slowing or stopping destruction of the medial joint compartment. To maintain the stability of OWHTO, the most common type of plate was T-Plate as the locking compression plate (LCP) concept. Anterior portion of T-Plate infringe patient's soft tissue resulted in some complications, whereas anatomical L-plate does not. To evaluate the structural stability of the anatomically contoured L-plate in the present study, the effect of weight bearing after osteotomy should be reviewed in the point of the stress of the plate and screws. We hypothesize that its stress path diverge through collateral portion of tibia and the stress level in screws lowered comparing to the result of T-plate presented in existing literature.

Materials and Methods

Based on the postoperative CT data were made from the reconstruction model for finite-element model. The value of Young's modulus and Poisson's ratio were 17,000MPa and 0.36 for cortical bone and 300MPa and 0.3 for cancellous bone. The anatomically contoured L-Plate system, the material of all plate systems were surgical Ti-Alloy were homogeneous and linear properties (Young's modulus = 113,000MPa, Poisson's ratio = 0.33). The screw system were the same as the material properties of the anatomically contoured L-Plate system. For finite element analysis, both the bone and screws were contacted as general condition. And the screws and plate were contacted as tie contact(Figure 1). The load conditions were applied to the top of the tibia based physiological (=1400N) and surgical loads (=200N). In this study, the compressive-bending load was applied to the two nodal points corresponding to the centers of each tibial condyle and divided into 60% and 40% to the medial and lateral sides, respectively. The physiological loads applied in the quadrant section on the proximal tibia.(Chu-An Luo, 2013)

Background

Although the wear of conventional polyethylene liner becomes a serious problem in a long term follow up after total knee arthroplasty, there are few reports of measuring the polyethylene wear.

Questions/purposes

Is it possible to measure the linear wear rates in the non-cross-linked polyethylene liner used in the Press Fit Condylar (PFC) Sigma total knee system? Does the polyethylene wear influence on the clinical results?

Introduction

The epidemiology of re-revision total hip arthroplasty (THA) is not well understood. The purpose of this study is to investigate the epidemiology of re-revision THA, and identify risk factors that are associated with failure of re-revision THA.

Methods

A retrospective analysis was performed on 288 patients who underwent revision THA at a single institution between 1/2012 and 12/2013. Patients who underwent revision hip arthroplasty two or more times were included. Patients were excluded if their indication for their first revision was due to periprosthetic joint infection (PJI). Patient demographics, surgical indications, revision details, and available follow-up information were collected through the electronic medical record. Re-revision failure was defined as the need for any additional return to the operating room, regardless of indication. A logistic regression analysis was performed to assess for significant predictors of re-revision failure.

Introduction

Revision Total Knee Arthroplasty (TKA) is becoming increasingly prevalent as the number of TKA procedures grow in a younger, higher-demand population. Factors associated with patients requiring multiple revision TKAs are not yet well understood. The purpose of this study is to investigate the epidemiology of re-revision TKA, and identify risk factors that are associated with failure of re-revision TKA.

Methods

A retrospective analysis was performed on 358 patients who underwent revision TKA at a single institution between 1/2012 and 12/2013. Patients who underwent revision knee arthroplasty two or more times were included. Patients were excluded if their indication for the first revision was periprosthetic joint infection (PJI). Patient demographics, surgical indications, revision details, and available follow-up information were collected. Re-revision failure was defined as the need for any additional operative intervention. A logistic regression analysis was performed to assess for significant predictors of re-revision failure.

Introduction

Loads acting on the knee are tied to the long term performance of implants, and are directly related to ligament function [1]. Previous work has used computational models coupled with optimization to estimate ligament properties based on experimental joint kinematics [2]. Our group recently utilized a similar optimization scheme that estimated ligament slack lengths based on experimental implant contact metrics [3]. A comparison with surgically relevant loading conditions that were excluded from the optimization would help establish the utility of the simulation framework. Hence, the purpose of this study was to assess the predictive capability of two simulated knees using comparisons with experimentally determined trends found after systematic removal of key tissues. Similar techniques may support clinical joint balancing techniques, as well as identify factors that dictate long term implant performance.

Methods

Knee arthroplasty was performed by orthopedic surgeons for four cadaveric specimens. Instrumented trial inserts (VERASENSE, OrthoSensor, Inc., Dania Beach, FL) were used and experimentation utilized the simVITROTM robotic musculoskeletal simulator (Cleveland Clinic, Cleveland, OH) to measure tibiofemoral kinematics under interoperative style loading. Three successive laxity style tests were performed at 10° flexion: anterior-posterior force (±100 N), varus-valgus moment (±5 Nm), and internal-external moment (±3 Nm). Kinematics and implant forces were measured throughout testing. Specimens were first tested in the intact state, then the laxity tests were repeated after systematic release of the posterior cruciate ligament (PCL), superficial medial collateral ligament (sMCL), or popliteus (POP). Significant changes in kinematics and contact metrics were determined using regression analysis between the intact versus the tissue released states.

Finite element models were developed for two specimens, and optimized ligament slack lengths were found using methods described previously [3] (Fig. 1). The experimental laxity style loads were applied to both optimized models with intact ligaments, and with individually released PCL, sMCL, or POP ligaments. Knee kinematics and tibial contact loads were predicted, and trended responses from the intact simulations to those with released ligaments were determined (i.e. higher, lower or no change). Simulation results were then compared with the statistically significant findings from the experimental tests.

Introduction

Joint mechanics and implant performance have been shown to be sensitive to ligament properties [1]. Computational models have helped establish this understanding, where optimization is typically used to estimate ligament properties for recreation of physically measured specimen-specific kinematics [2]. If available, contact metrics from physical tests could be used to improve the robustness and validity of these predictions. Understanding specimen-specific relationships between joint kinematics, contact metrics, and ligament properties could further highlight factors affecting implant survivorship and patient satisfaction.

Instrumented knee implants offer a means to measure joint contact data both in-vivo and intra-operatively, and can also be used in a controlled experimental environment. This study extends on previous work presented at ISTA [3], and the purpose here was to evaluate the use of instrumented implant contact metrics during optimization of ligament properties for two specimens. The overarching goal of this work is to inform clinical joint balancing techniques and identify factors that are critical to implant performance.

Methods

Total knee arthroplasties were performed on 4 (two specimens modeled) cadeveric specimens by an experienced orthopaedic surgeon. An instrumented trial implant (VERASENSE, OrthoSensor, Inc., Dania Beach, FL) was used in place of a standard insert. Experimentation was performed using a simVITROTM controlled robotic musculoskeletal simulator (Cleveland Clinic, Cleveland, OH) to apply intra-operative style loading and measure tibiofemoral kinematics. Three successive laxity style tests were performed at 10° knee flexion: anterior-posterior force (±100 N), varus-valgus moment (±5 Nm), and internal-external moment (±3 Nm). Tibiofemoral kinematics and instrumented implant contact metrics were measured throughout testing (Fig. 1).

Specimen-specific finite element models were developed for two of the tested specimens and solved using Abaqus/Explicit (Dassault Systèmes). Relevant ligaments and rigid bone geometries were defined using specimen-specific MRIs. Virtual implantation was achieved using registration and each ligament was modeled as a set of nonlinear elastic springs (Fig. 1). Stiffness values were adopted from the literature [2] while the ligament slack lengths served as control variables during optimization. The objective was to minimize the root mean square difference between VERASENSE measured tibiofemoral contact metrics and the corresponding model results (Fig. 1).

Introduction

Historically, knee implants have been designed using average patient anatomy and despite excellent implant survivorship, patient satisfaction is not consistently achieved. One possibility for this dissatisfaction relates to the individual patient anatomic variability. To reduce this inter-patient variability, recent advances in imaging and manufacturing have allowed for the implementation of patient specific posterior cruciate retaining (PCR) total knee arthroplasty (TKA). These implants are individually made based on a patient's femoral and tibial anatomy determined from a pre-operative CT scan. Although in-vitro studies have demonstrated promising results, there are few studies evaluating these implants in vivo. The objective of this study was to determine the in vivo kinematics for subjects having a customized, individually made(CIM) knee implant or one of several traditional, off-the-shelf (OTS) TKA designs.

Methods

In vivo kinematics were assessed for 108 subjects, 44 having a CIM-PCR-TKA and 64 having one of three standard designs, OTS-PCR-TKA which included symmetric TKA(I), single radius TKA(II) and asymmetric TKA(III) designs. A mobile fluoroscopic system was used to observe subjects during a weight-bearing deep knee bend (DKB), a Chair Rise and Normal Gait. All the subjects were implanted by one of two surgeons and were clinically successful (HSS Score>90). The kinematic comparison between the three designs involved range of motion, femoral translation, axial rotation, and condylar lift-off.

Purpose

The aim of this study was to compare the accuracy of limb alignment and component positioning after total knee arthroplasty(TKA) performed using fixed or individual distal femoral valgus correction angle(VCA)in valgus knees.

Materials and Methods

One hundred and twenty-four patients were randomised to undergo TKA with either of the clinical baseline, radiological outcomes and subsequent outcome such as knee HSS scores, knee range of motion (ROM) and visual analogue scale (VAS) scores were assessed. Knees in the individual group (n=62) were performed with a tailored VCA. Knees in the fixed group (n=62) were performed utilizing a 4°VCA.

Purpose

Recently many authors have questioned the role of tourniquets in primary knee arthroplasty (TKA). Meanwhile, whether the use of an intra-articular wound drainage is an advance over the lack of a drain in TKA is controversial in the literature. This study aimed to investigate the efficacy and safety of drainage or not in TKA without a tourniquet.

Methods

Eighty participants who underwent primary unilateral TKA were prospectively enrolled and were randomized to one of two techniques during surgery without a tourniquet: drainage (Group A) or non-drainage (Group B). Blood loss was monitored perioperatively. The operating time, allogeneic blood transfusion rate, thigh pain, knee pain, limb swelling, clinical outcome as measured by the hospital for special surgery (HSS) score, the ability to straight-leg raise, visual analog scale (VAS) in pain, length of stay and knee active range of motion (ROM) were also recorded. The digital radiographs taken at 6 months postoperatively were assessed for cement mantle thickness and radiolucency using the Knee Society radiographic zones.

Introduction

The limited field of view with less-invasive hip approaches for total hip arthroplasty can make a reliable cup positioning more challenging. The aim of this study was to evaluate the accuracy of cup placement between the traditional transgluteal approach and the anterior approach in a routine setting.

Objectives

We asked if the (1) accuracy, (2) precision, and (3) number of outliers of the prosthetic cup orientation differed between three study groups: the anterior approach in supine position, the anterior approach in lateral decubitus position, and the transgluteal approach in lateral decubitus position.

Introduction

Acetabular retroversion is an accepted cause of Pincer-type femoroacetabular impingement. There is increasing evidence that acetabular retroversion is rather a rotational abnormality of the pelvis than an overgrowth of the acetabular wall or even a dysplasia of the posterior wall. Initially, patients with a retroverted acetabulum were treated with an open rim trimming through a surgical hip dislocation (SHD) based on the early understanding of the pathomorphology. Theoretically, the reduction of the anterior wall can decrease the already small joint contact area in retroverted hips to a critical size. Based on the most recent literature, anteverting periacetabular osteotomy (PAO) seems to be the more appropriate surgical treatment. With this technique, the anterior impingement conflict can be treated efficiently without compromising the joint contact area. However, it is unknown whether this theoretical advantage in turn results in better mid term results of treatment.

Objectives

We asked if anteverting PAO results in better clinical and radiographical mid term results compared to rim trimming through a surgical hip dislocation.