Knee replacement is a proven and reproducible procedure to alleviate pain, re-establish alignment and restore function. However, the quality and completeness to which these goals are achieved is variable.

The idea of restoring function by reproducing condylar anatomy and asymmetry has been gaining favor. As knee replacements have evolved, surgeons have created a set of principles for reconstruction, such as using the femoral transepicondylar axis (TEA) in order to place the joint line of the symmetric femoral component parallel to the TEA, and this has been shown to improve kinematics. However, this bony landmark is really a single plane surrogate for independent 3-dimensional medial and lateral femoral condylar geometry, and a difference has been shown to exist between the natural flexion-extension arc and the TEA. The TEA works well as a surrogate, but the idea of potentially replicating normal motion by reproducing the actual condylar geometry and its involved, individual asymmetry has great appeal.

Great variability in knee anatomy can be found among various populations, sizes, and genders. Each implant company creates their specific condylar geometry, or “so called” J curves, based on a set of averages measured in a given population. These condylar geometries have traditionally been symmetric, with the individualised spatial placement of the (symmetric) curves achieved through femoral component sizing, angulation, and rotation performed at the time of surgery. There is an inherent compromise in trying to achieve accurate, individual medial and lateral condylar geometry reproduction, while also replicating size and avoiding component overhang with a set implant geometry and limited implant sizes. Even with patient-specific instrumentation using standard over-the-counter implants, the surgeon must input his/her desired endpoints for bone resection, femoral rotation, and sizing as guidelines for compromise. When all is done, and soft tissue imbalance exists, soft tissue release is the final, common compromise.

The custom, individually made knee design goals include reproducible mechanical alignment, patient-specific fit and positioning, restoration of articular condylar geometry, and thereby, more normal kinematics. A CT scan allows capture of three-dimensional anatomical bony details of the knee. The individual J curves are first noted and corrected for deformity, after which they are anatomically reproduced using a Computer-Aided Design (CAD) file of the bones in order to maximally cover the bony surfaces and concomitantly avoid implant overhang. No options for modifications are offered to the surgeon, as the goal is anatomic restoration.

Given these ideals, to what extent are patients improved? The concept of reproducing bony anatomy is based on the pretext that form will dictate function, such that normal-leaning anatomy will tend towards normal-leaning kinematics. Therefore, we seek to evaluate knee function based on objective assessments of movement or kinematics.

In summary, the use of custom knee technology to more closely reproduce an individual patient's anatomy holds great promise in improving the quality and reproducibility of postoperative function. Compromises of fit and rotation are minimised, and implant overhang is potentially eliminated as a source of pain. Early results have shown objective improvements in clinical outcomes. Admittedly, this technology is limited to those patients with mild to moderate deformity at this time, since options like constraint and stems are not available. Yet these are the patients who can most clearly benefit from a higher functional state after reconstruction. Time will reveal if this potential can become a reproducible reality.

The first rule in properly cementing a femoral component is obtaining adequate exposure of the proximal femur. This is achieved reproducibly in anterior approach surgery with anterior and superior capsulotomy, combined with release of the conjoined tendon from the inner trochanter and piriformis tendon retraction, or flip behind the trochanter. This will be demonstrated.

The steps of cementation are well established, and not specific to one approach. They involve entry to the proximal femur in a lateral and posterior position, achieving central alignment within the proximal femur with the broach, application of a cement restrictor to a point 1.5 to 2cm distal to the proposed tip of the implant, appropriate preparation of the cancellous bone to receive the cement, applying cement in a sufficiently doughy state to be able to achieve penetration into the cancellous bone, and mechanical pressurization into that cancellous bone. We routinely apply cement directly to the proximal aspect of the femoral component as the cement sticks to the metal, preventing marrow contents generated during the insertion from contacting the metal. In discussing the factors contributing to a dry surgical field, the importance of relative hypotension achieved from regional anesthesia cannot be overstated.

Modifiable factors contributing to stiffness include alignment, implant size, implant position and rotation, and soft tissue tightness or laxity. Less modifiable factors include genetics as in predisposition to inflammation and fibrosis, aberrations in perception and experience of emotional pain, and preoperative range of motion.

We reviewed 559 knees undergoing revision between 2007 and 2014, selecting out patients with a diagnosis of stiffness and greater than one-year follow-up. Stiffness was defined as greater than 15 degrees of flexion contracture or less than 75 degrees of flexion or less than 90 degrees of active motion and a chief complaint of limited motion and pain. Radiographic analysis used a set of matched controls with greater than 90 degrees and full extension prior to surgery and were further matched by age, gender, BMI.

Flexion contracture changed from an average of 9.7 to an average of 2.3 degrees, flexion changed from an average of 81 to an average of 94 degrees, active motion changed from an average of 72 to an average of 92 degrees, pain scores improved from 44 to 72 points, and Knee Society function scores improved from an average of 49 to an average of 70 points. There were four failures for stiffness, two knees underwent additional manipulation, gaining an average of 10 degrees; and two knees were revised.

Radiographic analysis demonstrated stiffness to be strongly correlated to anterior condylar offset ratio and to patellar displacement by multivariant regression analysis, suggesting that overstuffing the patellofemoral joint by anteriorization of the femoral component is associated with stiffness. Using modern revision techniques, revision for stiffness creates reliable improvements in pain, Knee Society clinical and functional scores, and motion.

Knee replacement is a proven and reproducible procedure to alleviate pain, re-establish alignment and restore function. However, the quality and completeness to which these goals are achieved is variable. The idea of restoring function by reproducing condylar anatomy and asymmetry has been gaining favor. As knee replacements have evolved, surgeons have created a set of principles for reconstruction, such as using the femoral transepicondylar axis (TEA) in order to place the joint line of the symmetric femoral component parallel to the TEA, and this has been shown to improve kinematics. However, this bony landmark is really a single plane surrogate for independent 3-dimensional medial and lateral femoral condylar geometry, and a difference has been shown to exist between the natural flexion-extension arc and the transepicondylar axis. The TEA works well as a surrogate, but the idea of potentially replicating normal motion by reproducing the actual condylar geometry and its involved, individual asymmetry has great appeal.

Great variability in knee anatomy can be found among various populations, sizes, and genders. Each implant company creates their specific condylar geometry, or “so called” J curves, based on a set of averages measured in a given population. These condylar geometries have traditionally been symmetric, with the individualised spatial placement of the (symmetric) curves achieved through femoral component sizing, angulation, and rotation performed at the time of surgery. There is an inherent compromise in trying to achieve accurate, individual medial and lateral condylar geometry reproduction, while also replicating size and avoiding component overhang with a set implant geometry and limited implant sizes. Even with patient-specific instrumentation using standard over-the-counter implants, the surgeon must input his/her desired endpoints for bone resection, femoral rotation, and sizing as guidelines for compromise. When all is done, and soft tissue imbalance exists, soft tissue release is the final, common compromise.

The custom, individually made knee design goals include reproducible mechanical alignment, patient-specific fit and positioning, restoration of articular condylar geometry, and thereby, more normal kinematics. A CT scan allows capture of three-dimensional anatomical bony details of the knee. The individual J curves are first noted and corrected for deformity, after which they are anatomically reproduced using a Computer-Aided Design (CAD) file of the bones in order to maximally cover the bony surfaces and concomitantly avoid implant overhang. No options for modifications are offered to the surgeon, as the goal is anatomic restoration.

In summary, the use of custom knee technology to more closely reproduce an individual patient's anatomy holds great promise in improving the quality and reproducibility of post-operative function. Compromises of fit and rotation are minimised, and implant overhang is potentially eliminated as a source of pain. Early results have shown objective improvements in clinical outcomes. Admittedly, this technology is limited to those patients with mild to moderate deformity at this time, since options like constraint and stems are not available. Yet these are the patients who can most clearly benefit from a higher functional state after reconstruction. Time will reveal if this potential can become a reproducible reality.

Bone loss creates a challenge to achieving fixation in revision TKR. Failure to achieve metaphyseal fixation is associated with failure in revision TKR. In the absence of cancellous bone for cement fixation, metaphyseal augments placed without cement have shown promise in achieving fixation. First generation augments were modular solid titanium sleeves attached to a taper at the base of the core implant. The introduction of tantalum with its favorable mechanical qualities markedly increased the utility and utilization of metaphyseal augments, with positive reports. These are either large augments where the bone is prepared with a burr, or later small cones placed with a cannulated broaching technique. Both have solved real problems, the first being limited by the reproducibility of bone preparation, and the second with excellent reproducibility of bone preparation but limited diameters. Other highly porous titanium surfaces have broadened the choices.

Modern metaphyseal augments seek to add flexibility and options, specifically the use of offset stems. One tibial augment design features a reamed cone with a matching conical implant. Another option is based on an anatomic cone design with a single ream and a broached technique to optimise endosteal cortical bone contact. With each of these options, the augment can be placed wherever the remaining bone exists for fixation, even down to the metaphyseal-diaphyseal junction, and not limited to the area adjacent to the cut surface of bone. Once independent fixation is achieved, the intramedullary stem is cemented inside of it.

Modern femoral augments are designed to sit either in the epiphyseal region, or the metaphysis. Cannulated reaming systems allow for preparation of complex asymmetrical double cone implants at the epiphysis. Metaphyseal implants are designed anatomically to sit deeper in the femoral bone, and can manage larger bony defects. Each system has benefits and compromises, and together they comprise increasingly powerful alternatives to manage extensive bone loss.

INTRO

Two-stage revision arthroplasty for PJI may make use of an antibiotic-loaded cement spacer (ACS), as successful long- term prevention of reinfection have been reported using this technique.[i] However, there is little data on systemic complications of high-dose antibiotic spacers. Acute kidney injury (AKI) is of clinical significance, as the drugs most commonly utilized, vancomycin and aminoglycosides, can be nephrotoxic. We intended to determine the incidence of AKI in patients that underwent staged revision arthroplasty with an ACS, as well as to identify potential predisposing risk factors for the disease.

Knee replacement is a proven and reproducible procedure to alleviate pain, re-establish alignment and restore function. However, the quality and completeness to which these goals are achieved is variable. The idea of restoring function by reproducing condylar anatomy and asymmetry has been gaining favor As knee replacements have evolved, surgeons have created a set of principles for reconstruction, such as using the femoral transepicondylar axis (TEA) in order to place the joint line of the symmetric femoral component parallel to the TEA, and this has been shown to improve kinematics. However, this bony landmark is really a single plane surrogate for 3-dimensional medial and lateral femoral condylar geometry, and a difference has been shown to exist between the natural flexion-extension arc and the TEA. The TEA works well as a surrogate, but the idea of potentially replicating normal motion by reproducing the actual condylar geometry and its involved, individual asymmetry has great appeal.

Great variability in knee anatomy can be found among various populations, sizes, and genders. Each implant company creates their specific condylar geometry, or “so called” J curves, based on a set of averages measured in a given population. These condylar geometries have traditionally been symmetric, with the individualised spatial placement of the (symmetric) curves achieved through femoral component sizing, angulation, and rotation performed at the time of surgery. There is an inherent compromise in trying to achieve accurate, individual medial and lateral condylar geometry reproduction, while also replicating size and avoiding component overhang with a set implant geometry and limited implant sizes. Even with patient-specific instrumentation using standard over-the-counter implants, the surgeon must input his/her desired endpoints for bone resection, femoral rotation, and sizing as guidelines for compromise. When all is done, and soft tissue imbalance exists, soft tissue release is the final, common compromise.

The custom, individually made knee design goals include reproducible mechanical alignment, patient-specific fit and positioning, restoration of articular condylar geometry, and thereby, more normal kinematics. A CT scan allows capture of three-dimensional anatomical bony details of the knee. The individual J curves are first noted and corrected for deformity, after which they are anatomically reproduced using a Computer-Aided Design (CAD) file of the bones in order to maximally cover the bony surfaces and concomitantly avoid implant overhang. No options for modifications are offered to the surgeon, as the goal is anatomic restoration.

Given these ideals, to what extent are patients improved? The concept of reproducing bony anatomy is based on the pretext that form will dictate function, such that normal-leaning anatomy will tend towards normal-leaning kinematics. Therefore, we seek to evaluate knee function based on objective assessments of movement or kinematics.

The use of custom knee technology to more closely reproduce an individual patient's anatomy holds great promise in improving the quality and reproducibility of post-operative function. Compromises of fit and rotation are minimised, and implant overhang is potentially eliminated as a source of pain. Early results have shown objective improvements in clinical outcomes. Admittedly, this technology is limited to those patients with mild to moderate deformity at this time, since options like constraint and stems are not available. Yet these are the patients who can most clearly benefit from a higher functional state after reconstruction. Time will reveal if this potential can become a reproducible reality.

Increasing data is emerging, consistently demonstrating a more rapid recovery for patients undergoing direct anterior approach (DAA) surgery. In one study, objective findings of early recovery including timed up and go tests, Functional Independence Measures are significantly faster in the first 2 weeks, and normalise by 6 weeks. A more recent randomised study shows a quicker achievement of the functional milestones of discontinuing walking aids, discontinuing opioids, stair ascent, and walking 6 blocks, as well as accelerometer measures of activity in the first 2 weeks after surgery. In both of these studies, seasoned surgeons well beyond their learning curves performed the surgeries.

A prospective MRI study of volume before and after surgery has shown full recovery or mild hypertrophy of most muscles at an average of 24 weeks from surgery, but a sustained loss of muscle volume for the obturator internus muscle in the DAA, and sustained loss of muscle volume for obturator internus, obturator externus, piriformis, and quadratus femoris in the posterior approach patients. The muscles that are released in the surgeries recover incompletely.

Prospective assessment of muscle strength demonstrated loss of flexion strength in the DAA group and loss of external rotation strength in the posterior group at 6 weeks. By 3 months, the DAA group had returned to normal in their strength, while the posterior group had persistent external rotation weakness.

Prospective assessment of gait, pre-operatively and at 6 months showed similar improvements in frontal and sagittal plane range of movement in gait, with a similar improvement in transverse plane movement (internal and external rotation) in the DAA group, but no change in the posterior cohort.

The precision of socket placement, after undergoing a learning curve, was greater with the use of fluoroscopy in the DAA.

Cutting and subsequently repairing a muscle can have a clinically insignificant, but nonetheless objectively measurable effect on the function of that muscle.

Observed downsides of DAA include a higher prevalence of wound complications in obese patients, and possibly a higher risk of periprosthetic fractures in elderly, thin women. Recent larger registry data would also suggest that there is no difference in dislocation rate between the 2 referenced approaches, and possibly a higher femoral revision rate for the DAA. These may be honest and real depictions of a large learning curve as we further understand and disseminate the subtleties of proper execution of DAA surgery.

Increasing data is emerging, consistently demonstrating a more rapid recovery for patients undergoing direct anterior approach (DAA) surgery. In one study, objective findings of early recovery including timed up and go tests, Functional Independence Measures are significantly faster in the first 2 weeks, and normalise by 6 weeks. A more recent randomised study shows a quicker achievement of the functional milestones of discontinuing walking aids, discontinuing opioids, stair ascent, and walking 6 blocks, as well as accelerometer measures of activity in the first 2 weeks after surgery. In both of these studies, seasoned surgeons well beyond their learning curves performed the surgeries.

A prospective MRI study of volume before and after surgery has shown full recovery or mild hypertrophy of most muscles at an average of 24 weeks from surgery, but a sustained loss of muscle volume for the obturator internus muscle in the DAA, and sustained loss of muscle volume for obturator internus, obturator externus, piriformis, and quadratus femoris in the posterior approach patients. The muscles that are released in the surgeries recover incompletely.

Prospective assessment of muscle strength demonstrated loss of flexion strength in the DAA group and loss of external rotation strength in the Posterior group at 6 weeks. By 3 months, the DAA group had returned to normal in their strength, while the Posterior group had persistent external rotation weakness.

Prospective assessment of gait, pre-operatively and at 6 months showed similar improvements in frontal and sagittal plane range of movement in gait, with a similar improvement in transverse plane movement (internal and external rotation) in the DAA group, but no change in the Posterior cohort.

The precision of socket placement, after undergoing a learning curve, was greater with the use of fluoroscopy in the DAA.

Cutting and subsequently repairing a muscle can have a clinically insignificant, but nonetheless objectively measurable effect on the function of that muscle.

Observed downsides of DAA include a higher prevalence of wound complications in obese patients, and possibly a higher risk of periprosthetic fractures in elderly, thin women. Recent larger registry data would also suggest that there is no difference in dislocation rate between the 2 referenced approaches, and possibly a higher femoral revision rate for the DAA. These may be honest and real depictions of a large learning curve as we further understand and disseminate the subtleties of proper execution of DAA surgery.

Modularity in femoral revision evolved to address the specific weaknesses in the execution and results of the early Wagner SL stem, namely dislocations and subsidence. With modularity, distal canal fit can be achieved independently, and the proximal geometry can be created to re-establish the leg length and offset. The benefits of modularity relate specifically to being able to modify a plan intra-operatively based on the conditions that are encountered in mid battle. Inherent in this concept is the principle of predictability. The extent to which the conditions of operation may change requires alternatives to manage those changes. More importantly we need to be able to predict how an implant will sit in the bone.

At the inception and with subsequent manifestations of modular fluted stems, our ability to predict where the final implant will seat based on the trial options that existed was poor. For this reason, some modular stem designs offered no trial. This was part of the imperative for modularity, so that if the implant set too high it could be easily removed with reaming a little deeper and put back in. If the stem sat more deeply than had been anticipated, the change could be compensated by an alteration in the proximal modular segment. Reproducible mid- to long-term results have been published with this type of stem. Potential negatives of the modular junction include stem breakage, fretting and corrosion, cost, and the need to accommodate a large sized proximal segment within the proximal femur. The most important feature in modern non-modular implants will be predictability. We need to be able to predict that the final reamer will sit at a particular level in the femoral bone, and the trial will reproduce this level, and the final implant will reproduce this level. More importantly, we need to be able to predict that implants will remain where they are put, and not subside.

Subsidence has been causally associated with implant under-sizing, which is an error in surgical execution. As such, design features that optimise the ability to achieve intimate and broad endosteal contact between the implant and the bone can help reduce subsidence. These include precise, sharp reamers, implants in 1 mm increments, and trials that reproduce the position of the final implant. A larger implant is less likely to break, and we recommend preparation for the largest implant that the diaphysis can accommodate, often evident in the tactile feedback from the reamer, and the quality of the reamed bone being removed. Reaming is performed eccentrically in the proximal femur, so as to engage the diaphysis optimally.

The need for a kink in the stem is important for modular stems, which have bulky proximal segments that can create conflict with the peritrochanteric bone in smaller patients. Non-modular stems can have a smaller proximal diameter, such that a straight stem can be accommodated in most revision cases.

Early follow-up of a modern non-modular stem has shown excellent clinical improvement and reproducible ingrowth. Subsidence of > 10 mm occurred in 6 hips (6%), which is a notable improvement in historical values for this stem type, but remain short of some reports with modular stems. Improvements in goals and techniques of reaming and implantation are surely part of the improvements that have been documented, as well as those yet to be realised. Predictability will lead to simplicity and intuitiveness.

Knee replacement is a proven and reproducible procedure to alleviate pain, re-establish alignment and restore function. However, the quality and completeness to which these goals are achieved is variable. The idea of restoring function by reproducing condylar anatomy and asymmetry has been gaining favor. As knee replacements have evolved, surgeons have created a set of principles for reconstruction, such as using the femoral transepicondylar axis (TEA) in order to place the joint line of the symmetric femoral component parallel to the TEA, and this has been shown to improve kinematics. However, this bony landmark is really a single plane surrogate for 3-dimensional medial and lateral femoral condylar geometry, and a difference has been shown to exist between the natural flexion-extension arc and the TEA. The TEA works well as a surrogate, but the idea of potentially replicating normal motion by reproducing the actual condylar geometry and its involved, individual asymmetry has great appeal.

Great variability in knee anatomy can be found among various populations, sizes, and genders. Each implant company creates their specific condylar geometry, or “so called” J curves, based on a set of averages measured in a given population. These condylar geometries have traditionally been symmetric, with the individualised spatial placement of the (symmetric) curves achieved through femoral component sizing, angulation, and rotation performed at the time of surgery. There is an inherent compromise in trying to achieve accurate, individual medial and lateral condylar geometry reproduction, while also replicating size and avoiding component overhang with a set implant geometry and limited implant sizes. Even with patient-specific instrumentation using standard over-the-counter implants, the surgeon must input his/her desired endpoints for bone resection, femoral rotation, and sizing as guidelines for compromise. When all is done, and soft tissue imbalance exists, soft tissue release is the final, common compromise.

The custom, individually made knee design goals include reproducible mechanical alignment, patient-specific fit and positioning, restoration of articular condylar geometry, and thereby, more normal kinematics. A CT scan allows capture of three-dimensional anatomical bony details of the knee. The individual J curves are first noted and corrected for deformity, after which they are anatomically reproduced using a Computer-Aided Design (CAD) file of the bones in order to maximally cover the bony surfaces and concomitantly avoid implant overhang. No options for modifications are offered to the surgeon, as the goal is anatomic restoration.

Given these ideals, to what extent are patients improved? The concept of reproducing bony anatomy is based on the pretext that form will dictate function, such that normal-leaning anatomy will tend towards normal-leaning kinematics. Therefore, we seek to evaluate knee function based on objective assessments of movement or kinematics.

In summary, the use of custom knee technology to more closely reproduce an individual patient's anatomy holds great promise in improving the quality and reproducibility of post-operative function. Compromises of fit and rotation are minimised, and implant overhang is potentially eliminated as a source of pain. Early results have shown objective improvements in clinical outcomes. Admittedly, this technology is limited to those patients with mild to moderate deformity at this time, since options like constraint and stems are not available. Yet these are the patients who can most clearly benefit from a higher functional state after reconstruction. Time will reveal if this potential can become a reproducible reality.

BACKGROUND

This study aims to identify recent trends in discharge disposition following bilateral total knee arthroplasty (TKA) as well as factors that predispose patients to enter inpatient rehabilitation facilities (IRF) or skilled nursing facilities (SNF) versus home-rehabilitation (HR). The goal was to identify risk factors that predispose prolonged hospital stays and identify changes in management over time that may be responsible for decreased length of stay (LOS) and a HR program.

Introduction

The incidence of periprosthetic fractures is increasing as the population ages. Wound complications and surgical site infections following surgery to treat periprosthetic fractures are a major source of patient morbidity and health care burden. This study evaluates the efficacy of closed-incision negative-pressure wound therapy (ciNPT) in decreasing wound complications and surgical site infections (SSIs) after periprosthetic fracture surgery about the hip and knee.

Introduction

Stiffness after total knee arthroplasty (TKA) has been reported to occur due to component malpositioning and/or oversizing, improper femoral component (FC) flexion and tibial component (TC) slope, tight extension gap, inaccurate joint line placement, deficient posterior osteophyte resection, heterotopic ossification (HO), poor patellofemoral joint reconstruction, poor posterior condylar offset restoration, and/or posterior cruciate ligament (PCL) under-resection or retraction. However, the importance of these potential factors for stiffness are not well documented in the medical literature. The aim of this study was therefore to evaluate specific radiographic parameters in patients who had stiffness after primary TKA.

Introduction

A stiff total knee arthroplasty (TKA) is an uncommon but disabling problem because it causes pain and limited function. Revision surgery has been reported as a satisfactory treatment option for stiffness with modest benefits. The aim of this study was to evaluate the results of revision surgery for the treatment of stiffness after TKA.

Introduction

Iliopsoas impingement is a well described cause of groin pain after direct anterior total hip arthroplasty (THA). We proposed to evaluate the incidence, natural history and response to treatment of iliopsoas impingement after direct anterior total hip arthroplasty.

Introduction

Prosthetic replacement remains the treatment of choice for displaced femoral neck fractures in the elderly population, with recent literature demonstrating significant functional benefits of total hip arthroplasty (THA) over hemiarthroplasty. Yet the fracture population also has historically high rates of early postoperative instability when treated with THA. The direct anterior approach (DAA) may offer the potential to decrease the risk of postoperative instability in this high-risk population by maintaining posterior anatomic structures. The addition of intraoperative fluoroscopy can improve precision in component placement and overcome limitations on preoperative planning due to poor preoperative radiographs performed in the emergency setting.

Introduction

Symptomatic instability following total knee arthroplasty (TKA) is a leading cause of early failure. Despite numerous reports on instability, standardized diagnostic and treatment protocols for these patients continue to remain unclear. Most reports recommend component revision as the preferred treatment, because of poor outcomes and high failure rates associated with isolated tibial polyethylene insert exchange (ITPIE). However, modern implant systems and standardized protocols may potentially change this teaching.

Background

Posterior referencing (PR) total knee arthroplasty (TKA) aims to restore posterior condylar offset. When a symmetric femoral implant is externally rotated (ER) to the posterior condylar axis, it is impossible to anatomically restore the offset of both condyles. PR jigs variously reference medially, laterally, or centrally. The distal femoral cutting jigs typically reference off the more distal medial condyle, causing distal and posterior resection discrepancies. We used sawbones to elucidate differences between commonly used PR cutting jigs with regards to posterior offset restoration.

Introduction

Total hip arthroplasty (THA) is a common operation. Different operative approaches have specific benefits and compromises. Soft tissue injury occurs in total hip arthroplasty. This prospective study objectively measured muscle volume changes after direct anterior and posterior approach surgeries.