Introduction

Vitamin D deficiency is common in patients undergoing total hip (THA) or total knee arthroplasty (TKA) which may affect prosthesis survival and 90-day readmission rates. The purpose of this study was to assess whether preoperative Vitamin D deficiency or insufficiency have an influence on revision, readmission, and complication rates following THA and TKA. We hypothesized that low Vitamin D levels in patients undergoing THA and TKA have a negative effect on revision rates.

Introduction

Arthrofibrosis following total knee arthroplasty (TKA) is a complex and multifactorial complication that may require manipulation under anesthesia (MUA). However, patient and surgical factors that potentially influence the development of knee stiffness following TKA are not fully understood. The purpose of this study was to identify patient and surgical factors that may influence arthrofibrosis following TKA by assessing a cohort of patient that underwent MUA and comparing them to a matched cohort of patients without arthrofibrosis.

Introduction

The number of complex revision total hip arthroplasties (THA) is predicted to rise. The identification of acetabular bone defects prior to revision THA has important implications on technique and complexity of acetabular reconstruction. Paprosky et al. proposed a classification system including 3 main types with up to 3 subtypes focused on the integrity of the superior rim of the acetabulum and medial wall. However, the classification system is complex and its reliability has been questioned. The purpose of this study was to evaluate the effectiveness of different radiologic imaging modalities (plain radiographs, 2-D CT, 3-D CT reconstructions) in classifying acetabular defects in revision hip arthroplasty cases and their value of at different levels of orthopaedic training.

Background

Fifteen to twenty percent of patients presenting for total hip arthroplasty (THA) have bilateral disease. While simultaneous bilateral THA is of interest to patients and surgeons, debate persists regarding its merits. The majority of previous reports on simultaneous bilateral THA involve patients in the lateral decubitus position, which require repositioning, prepping and draping, and exposure of a fresh wound to pressure and manipulation for the contralateral THA. The purpose of this study was to compare complications, component position, and financial parameters for simultaneous versus staged bilateral THAs using the direct anterior approach (DAA).

Introduction

Unicompartmental knee arthroplasty (UKA) has seen renewed interest in recent years and is a viable option for patients with limited degenerative disease of the knee as an alternative to total knee arthroplasty. However, the minimally invasive UKA procedure is challenging, and accurate component alignment is vital to long-term survival. Robotic-assisted UKA allows for greater accuracy of component placement and dynamic intraoperative ligament balancing which may improve clinical patient outcomes. The purpose of this study was to analyse the clinical outcomes in a large, consecutive cohort of patients that underwent robotic-assisted UKA at a single institution with a minimum follow-up of 2 years. The study hypothesis was that robotic-assisted UKA improves patient outcomes by decreasing the rate of revision in comparison to conventional UKA.

Introduction

Unicompartmental knee arthroplasty (UKA) has seen renewed interest in recent years and is a viable option for patients with limited degenerative disease of the knee as an alternative to total knee arthroplasty. However, the minimally invasive UKA procedure is challenging and accurate component alignment is vital to long-term survival. Robotic-assisted UKA allows for greater accuracy of component placement and dynamic intraoperative ligament balancing which may improve clinical patient outcomes. The purpose of this study was to examine the clinical outcomes in a large, consecutive cohort of patients that underwent robotic-assisted UKA.

Unicompartmental knee arthroplasty (UKA) was first described over 30 years ago and allows replacement of a single compartment in patients who have isolated osteoarthritis. However, UKA is more technically challenging than total knee arthroplasty due to limited exposure as a minimally invasive procedure. In addition to component alignment and fixation, ligament balancing plays an important role in implant survival. Some failures of early UKA systems were attributed to a failure to adequately balance the knee. The development of robots to aid in performing the procedure has lead to renewed interest in this surgical technique. The use of a robot-assisted system allows the orthopaedic surgeon to verify that balancing sought pre-operatively correlates with that obtained at surgery. Some studies have shown good post-operative mechanical alignment utilizing this method. The aim of this study was to examine the variation in pre-operative templated ligament balance and that obtained during the operation.

Data were prospectively collected on 51 patients (52 knees) undergoing robot-assisted unicompartmental knee arthroplasty by a single surgeon. For pre-operative planning, dynamic ligament balancing was obtained of the operative knee under valgus stress, prior to any bony cuts. Final intra-operative images with the prosthesis in place were taken without valgus stress. Positive values denoted loose ligamentous balancing while negative values indicated ligament tightness.

A small variation of less than 1 mm was measured between the pre-operative plan and the final image with the implant in place. At 0 degrees the mean change was −0.26 mm (range, −4.40 to 2.20 mm), at 30 degrees −0.53 mm (range, −5.30 to 1.80 mm), at 60 degrees −0.04 mm (range, −3.10 to 2.30 mm) and at 90 degrees 0.16 mm (range, −2.70 to 2.00 mm). These results show that planned dynamic ligament balancing is accurate to within 0.52 mm.

The technological advancements with robotic feedback in orthopaedic surgery can aid in the success of unicompartmental knee replacement surgery. Ensuring that pre-operative templated changes match those performed during surgery is an important predictor of outcome. With proper planning prior to surgery, the use of a robot in UKA can improve ligament balancing. This can be done at various angles, ensuring excellent ligament balancing throughout the entire range of motion. Correct component alignment reduces the risk of prosthetic failure and may increase the length of implant survival. Further fine-tuning of the accuracy of feedback between the robot and the anatomical points will improve the accuracy of UKA.

Osteoarthritis of the knee is a debilitating condition affecting millions of persons, often requiring arthroplasty to relieve pain and improve mobility. For those patients with disease in only one compartment of the knee, unicompartmental knee arthroplasty (UKA) can be a viable surgical alternative. To date, there has not been a large series reported in the literature of UKAs performed with robotic assistance. The aim of this study was to examine the clinical outcomes of patients who underwent this procedure.

Five hundred and ten procedures in patients with a mean age of 63.7 years (range, 28 to 88 years) who underwent unicompartmental knee arthroplasty using a robotic-assisted system between July, 2008 and June, 2010 were identified. Clinical outcomes were evaluated using the Oxford Knee Score and patients without recent follow-up were contacted by telephone. The revision rate and time to revision were also examined.

The average length of stay for patients who underwent robot-assisted UKA was 1.4 days (range, 1 to 7 days). There was minimal blood loss with most procedures. At latest clinical follow-up, most patients were doing well after UKA with a mean Oxford Knee Score of 36.1 + 9.92. The revision rate was 2.5% with 13 patients being either converted from an inlay to onlay prosthesis or conversion to total knee arthroplasty. The most common indication for revision was tibial component loosening, followed by progression of arthritis. Mean time to revision was 9.55 + 5.48 months (range, 1 to 19 months).

Unicompartmental arthroplasty with a robotic system provides good pain relief and functional outcome at short-term follow-up. Ensuring correct component alignment and ligament balancing increases the probability of a favorable outcome following surgery. Proper patient selection for appropriate UKA candidates remains an important factor for successful outcomes.

INTRODUCTION

Unicompartmental knee arthroplasty (UKA) allows replacement of a single compartment in patients who have isolated osteoarthritis as a minimally invasive procedure. However, limited visualization of the surgical site provides challenges in ensuring accurate alignment and placement of the prosthesis.

With robot-assisted surgery, correct implant positioning and ligament balancing are obtainable with increased accuracy. To date, there has not been a large series reported in the literature of UKAs performed with robotic assistance. The aim of this study was to examine the clinical outcomes of robot-assisted UKA patients.

Introduction

Unicompartmental knee arthroplasty (UKA) was first described over 30 years ago and allows replacement of a single compartment in patients who have isolated osteoarthritis.¹ However, UKA is more technically challenging than total knee arthroplasty due to limited exposure as a minimally invasive procedure. In addition to component alignment and fixation, ligament balancing plays an important role in implant survival.² Some failures of early UKA systems were attributed to a failure to adequately balance the knee. The development of robots to aid in performing the procedure has lead to renewed interest in this surgical technique.

The use of a robot-assisted system allows the orthopaedic surgeon to verify that balancing sought pre-operatively correlates with that obtained at surgery. Some studies have shown good post-operative mechanical alignment utilizing this method.³ The aim of this study was to examine the variation in pre-operative templated ligament balance and that obtained during the operation.

Recently in the literature the indications of unicompartmental knee arthroplasty have been extended by the inclusion of patients with arthritis which is predominantly but not exclusively effecting the medial compartment. The aim of this study is to evaluate the outcome of MAKO unicondylar replacement in the treatment of knee osteoarthritis after the initial surgical insult is worn off to evaluate the impact of residual patellofemoral and lateral osteoarthritis on the outcome of medial unicompartmental knee replacement.

135 patients who underwent uncomplicated 144 MAKO medial unicondylar replacements for knee arthritis were identified and studied. Original radiographs were used to classify severity of patellofemoral and lateral compartmental osteoarthritis in these patients. Severity of patellofemoral and lateral compartmental osteoarthritis was analyzed against Oxford and Knee Society (AKSS) scores and amount of ipsilateral residual knee symptoms at 6 months post-operative period.

Pre-operative Oxford and Knee Society scores, and other comorbidities and long term disability were studied as confounding variables.

We found significant improvement in symptoms and scores in spite of other compartment disease. Poorer outcome was seen in association with comorbidities and long term disability but not when radiographic signs of arthritis in the other compartments were present. Six patients required revision of which three had (lateral facet) patellofemoral disease in the original x-rays.

In conclusion there is no direct relationship between postoperative symptoms and poor outcome and radiographic disease in the other compartments. However when symptoms are severe enough to necessitate revision this is due to patellofemoral and not lateral compartment disease.

Purpose: Suture anchors used for reinserting soft tissue on bony structures have been studied with the purpose of evaluating hold in bone. There has not however been any work on the influence of the eye design on suture resistance. The purpose of this work was to examine this aspect of the question.

Material and methods: The following anchors were tested: Statak 4 (Zimmer, Warsaw, IN, USA), Corkscrew 3.5, Fastak 2.4 (Arthrex, Naples, FL, USA), PeBA C 6.5 (OBL, Scottsdale, AZ, USA), Mitek GII 5Mitek, Norwood, MA, USA), Harpoon 2 (Arthrotek, Warsaw, IN? USA), Ultrafix (Linvatec, Largo, FL, USA), Vitis 3.5 AND 5 (Tornier, St Isnier, France). The following suture threads were used: Vicryl dec 5, Flexidene dec 5, PDS dec 4. Three types of tests were performed on an Instron 8500+. To study loading at thread rupture, a loop with a constant length was placed under traction in the axis of the anchor until thread rupture. Two measurement modalities were used. For the first, static tension was applied to increase the linear load at the rate of 1.25 mm/s. In the second, cyclic traction applied tension five times at a frequency of 1 Hz with 10N loading increments. To study thread weakening in relation to each anchor, we imposed a back and forth movement on the strand running through the eye using a sinusoidal 10 mm movement at a frequency of 0.03 Hz, one end of the thread being fixed and the other supporting a constant 20 N load. Each thread was tested in each anchor and each type of test was run three times.

Results: Load at rupture of each thread was not affected significantly by the design of the anchor eyes. Rupture generally occurred at the knot level, sometimes at the eye (Harpoon, Fastak, Vitis) for the Flexidene dec 5 thread. Conversely, there were important differences in the thread weakness tests: a knitted thread such as Vicryl was much stronger than the two other threads tested, irrespective of the anchor. Furthermore, resistance for the dynamic test was very variable for the different anchors: 100±20 cycles for corkscrew 3.5 and 3±1 cycles for Vitis 3.5 with Vicryl or 6+/1 cycles for Harpoon 2 with Flexidene.

Conclusion: The design and finishing of each eye had an effect on the resistance of thread moving through the eye. For anchors which weakened thread after a few back and forth movements, it can be assumed that simple knotting damages the thread to a point where early failure occurs at reinsertion. The best results were obtained when the anchor eye had a bevelled groove.