The etiology of the flexion contracture is related to recurrent effusions present in a knee with end-stage degenerative joint disease secondary to the associated inflammatory process. These recurrent effusions cause increased pressure in the knee causing pain and discomfort. Patients will always seek a position of comfort, which is slight flexion. Flexion decreases the painful stimulus by reducing pressure in the knee and relaxing the posterior capsule. Unfortunately, this self-perpetuating process leads to a greater degree of contracture as the disease progresses. Furthermore, patients rarely maintain the knee in full extension. Even during the gait cycle the knee is slightly flexed. As their disease progresses, patients limit their ambulation and are more frequently in a seated position. Patients often report sleeping with a pillow under their knee or in the fetal position. All of these activities increase flexion contracture deformity. Patients with excessive deformity >40 degrees should be counseled regarding procedural complexity and that increasing constraint may be required. Patients are seen preoperatively by a physical therapist and given a pre-arthroplasty conditioning program. Patients with excessive flexion contracture are specifically instructed on stretching techniques, as well as quadriceps rehabilitation exercises.

The focus in the postoperative physiotherapy rehabilitation program continues toward the goal of full extension. Patients are instructed in appropriate stretching regimes. Patients are immobilised for the first 24 hours in full extension with plaster splints, such as with a modified Robert Jones dressing. This dressing is removed on postoperative day one. The patient is then placed in a knee immobiliser and instructed to wear it at bed rest, during ambulation and in the evening, only removing for ROM exercises. In cases of severe flexion deformity >30 degrees, patients are maintained in full extension for 3–4 weeks until ROM is begun. Patients are encouraged to use a knee immobiliser for at least the first 6 weeks postoperatively.

Treating patients with flexion contracture involves a combination of bone resection and soft tissue balance. One must make every effort to preserve both the femoral and tibial joint line. In flexion contracture the common error is to begin by resecting additional distal femur, which may result in joint line elevation and mid-flexion instability. The distal femoral resection should remove that amount of bone being replaced with metal. Attention should be directed at careful and meticulous balance of the soft tissues and release of the contracted posterior capsule with re-establishment of the posterior recess, which will correct the majority of flexion contractures.

Inability to achieve ROM after TKA represents a frustrating complication for both patient and surgeon. Non-operative treatments for the stiff TKA include shoe lift in contralateral limb, stationery bicycle with elevated seat position, extension bracing, topical application of hand-held instruments to areas of soft tissue-dysfunction by a trained physical therapist over several outpatient sessions, and use of a low load stretch device. Manipulation under anesthesia is indicated in patients after TKA having less than 90 degrees ROM after 6 weeks, with no progression or regression in ROM. Other operative treatments range from a downsizing exchange of the polyethylene bearing to revision with a constrained device and low-dose irradiation in cases of severe arthrofibrosis.

The battle of revision TKA is won or lost with safe, effective, and minimally bony-destructive implant removal, protecting all ligamentous stabilisers of the knee and, most importantly, the extensor mechanism. For exposure, incisions should be long and generous to allow adequate access. A standard medial parapatellar capsular arthrotomy is preferred. A synovectomy is performed followed by debridement of all scar tissue, especially in the medial and lateral gutters. All peripatellar scar tissue is excised followed by release of scar tissue within the patellar tendon, allowing for displacement or everting of the patella. As patellar tendon avulsion at any time of knee surgery yields disastrous results, the surgeon should be continuously evaluating the patellar tendon integrity, especially while displacing/everting the patella and bringing the knee into flexion. If displacement/eversion is difficult, consider rectis-snip, V-Y quadricepsplasty, or tibial tubercle osteotomy. The long-held requisite for patellar eversion prior to component removal is inaccurate. In most cases simple lateral patellar subluxation will provide adequate exposure.

If a modular tibial system is involved, removal of the tibial polyethylene will decompress the knee, allowing for easier access to patellar, femoral, and tibial components. For patellar component removal, first identify the border of the patella, then carefully clean and debride the interface, preferably with electrocautery. If the tibial component is cemented all-polyethylene, remove using an oscillating saw at the prosthetic-bone interface. Debride the remaining cement with hand tools, ultrasonic tools, or burrs. Remove the remaining peg using a low-speed burr. If the tibial component is metal-backed, then utilise a thin saw blade or reciprocating saw to negotiate the undersurface of the component between the pegs. If pegs are peripherally located, cut with a diamond disc circular cutting tool. Use a trephine to remove the pegs.

For femoral component removal, identify the prosthetic-bone/prosthetic-cement interface then remove soft tissue from the interface, preferably with electrocautery. Disrupt the interface around all aspects of the component, using any of following: Gigli saw for cementless components only, micro saw, standard oscillating saw, reciprocating saw, a series of thin osteotomes, or ultrasonic equipment. If the femoral component is stemmed, remove the component in two segments using an appropriate screwdriver to remove the screw locking the stem to the component. Remove the femoral component with a retrodriver or femoral component extractor. Debride cement with hand tools or burr, using care to avoid bone fracture. If a stem is present, then remove with the appropriate extraction device. If “mismatch” exists, where femoral (or likewise, tibial) boss is smaller in diameter than the stem, creating a cement block prohibiting stem removal, remove the cement with hand tools or burr. If the stem is cemented, use hand tools, ultrasonic tools, or a burr to debride the cement. Curette and clean the canals.

For tibial component removal, disrupt the prosthetic-cement/prosthetic-bone interface using an oscillating or reciprocating saw. Gently remove the tibial component with a retrodriver or tibial extractor. If stem extensions are utilised, disengage and debride all proximal cement prior to removing the stem. If stem is present, then remove stem with appropriate extraction device. If stem is grit-blasted and well-fixed, create 8mm burr holes 1.5 to 2.5cm distal to tibial tray on medial aspect and a small divot using burr, then drive implant proximally with Anspach punch. Alternatively, a tibial tubercle osteotomy may be performed. If the stem is cemented, use hand tools, ultrasonic tools or burr to debride cement.

According to Webster's Dictionary, efficiency is defined as the capacity to produce desired results with a minimal expenditure of energy, money, time, and materials. For a surgeon performing an operative procedure this would mean “skillfulness in avoiding wasted time and effort.” (www.webster-dictionary.org) The essential ingredient to becoming efficient is to promote a culture of efficiency. There are 10 elements: 1) proactive surgeon perspective; 2) effective utilization of preoperative holding area; 3) preoperative planning / templating; 4) development of preference cards; 5) operating room set-up protocols; 6) operating room team concept; 7) streamlined instrument sets; 8) consistent operative workflow; 9) standardised closure / dressings; and 10) prompt and meticulous room turnover. Efficient performance of an operative procedure requires skillfulness in avoiding wasted time and effort. Perioperative efficiencies are optimised by development of “swing,” “flip,” or “double occupancy” criteria, understanding of timing of when to initiate the anesthetic block for the next case, skin closure routine by physician assistant/nurse practitioner/private scrub, and marking the operative site of your first two patients upon arrival to the hospital or surgery center. Utilise a pro-active approach to prepare case carts the day before surgery. The operating room team turns over their own rooms, with a “clean as you go” mentality. Develop a formalised communication process for patient flow issues, such as real-time push-to-talk group calling phones. Determine in advance the number of instrument sets required for the day's caseload to mitigate flash sterilization and decrease room turnover time. The goal of the surgeon is to be out of the operating room for 5 minutes in between cases before the next incision, utilizing that time to enter orders, communicate with the family, dictate, and mark the operative site of the patient who will follow the one in the case about to start. Implant selection can help if consistent. Everyone must know the instrument trays including surgeon, scrubs, and nurses. Minimise both the number of trays and the redundancy of instrumentation. Templating should be done in advance of the day of surgery. Keep your surgery consistent and always deliver your best product. The workflow for inpatient and outpatient surgeries should be the same: same implant, same approach, and same closure.

The culture of efficiency requires buy-in by all involved in the operative procedure. Every one entering the operating theatre should have proper body coverage – no hair visible, no nose visible. There should be a strict limit to needless activity: minimum opening of doors, no changing of personnel during an operation, and use of intercom/telephone to request equipment. As the surgeon and the team begin to embrace efficiency, surgical times will decrease. Multiple studies have demonstrated that increased surgical time is associated with a higher incidence of infection. This is secondary to time-dependent contamination of the surgical wound and field.

The take home message is to develop and embrace efficiency. Operating room efficiency is the product of multiple factors including preoperative preparation, skilled anesthesia team, motivated operating room staff, choreographed surgery, and well-designed instrumentation. The surgeon is the captain of the ship and the staff follows his or her lead. Your operating room days will flow smoothly. Your operations will proceed with minimal stress. You will spend less time drinking coffee between cases and have more free time at the end of the day. However, most importantly, you will deliver a quality product to your patient.

Total hip arthroplasty (THA) continues moving to the outpatient arena, and may be feasible for some conversion and revision scenarios. Controversy surrounds appropriate patient selection. The purpose of this study is to report complications associated with outpatient revision and conversion THA, and to determine if comorbidities are associated with complications or overnight stay.

From June 2013 through March 2018, 43 patients (44 hips) underwent conversion (n=12) or revision (n=32) THA at a free-standing ambulatory surgery center. Mean patient age was 58.4 years, and 52% of patients were male. Conversion procedures were for failed resurfacing in two, failed hemiarthroplasty in one, and failed fracture fixation with retained hardware in 9. Revision procedures involved head only in one, head and liner in 20, cup and head in 7, stem only in 2, and stem and liner in 2.

Forty-four (93%) were discharged same day without incident, none required transfer to acute facility, and 3 required overnight stay with 2 of these for convenience and only one for a medical reason, urinary retention. Three patients with early superficial infection were successfully treated with oral antibiotics. There were no major complications, readmissions, or subsequent surgeries within 90 days. One or more major comorbidities were present in 17 patients (39%) including 1 valvular disease, 8 arrhythmia, 2 thromboembolism history, 3 obstructive sleep apnea, 6 chronic obstructive pulmonary disease, 2 asthma, 4 frequent urination, and 1 renal disease. The single patient who stayed overnight for a medical reason had no major medical comorbidities.

Outpatient arthroplasty, including revision THA in some scenarios, is safe for many patients. Presence of medical comorbidities was not associated with risk of complications. The paradigm change of patient education, medical optimization, and a multimodal program to mitigate risk of blood loss and reduce need for narcotics facilitates performing arthroplasty safely in an outpatient setting.

The etiology of the flexion contracture is related to recurrent effusions present in a knee with end-stage degenerative joint disease secondary to the associated inflammatory process. These recurrent effusions cause increased pressure in the knee causing pain and discomfort. Patients will always seek a position of comfort, which is slight flexion. Flexion decreases the painful stimulus by reducing pressure in the knee and relaxing the posterior capsule. Unfortunately, this self-perpetuating process leads to a greater degree of contracture as the disease progresses. Furthermore, patients rarely maintain the knee in full extension. Even during the gait cycle the knee is slightly flexed. As their disease progresses, patients limit their ambulation and are more frequently in a seated position. Patients often report sleeping with a pillow under their knee or in the fetal position. All of these activities increase flexion contracture deformity. Patients with excessive deformity >40 degrees should be counseled regarding procedural complexity and that increasing constraint may be required. Patients are seen pre-operatively by a physical therapist and given a pre-arthroplasty conditioning program. Patients with excessive flexion contracture are specifically instructed on stretching techniques, as well as quadriceps rehabilitation exercises.

Avoiding Pitfalls and Complications: Treating patients with flexion contracture involves a combination of bone resection and soft tissue balance. One must make every effort to preserve both the femoral and tibial joint line. In flexion contracture the common error is to begin by resecting additional distal femur, which may result in joint line elevation and mid-flexion instability. The distal femoral resection should remove that amount of bone being replaced with metal. Attention should be directed at careful and meticulous balance of the soft tissues and release of the contracted posterior capsule with re-establishment of the posterior recess, which will correct the majority of flexion contractures.

Residual Flexion Contracture: Inability to achieve ROM after TKA represents a frustrating complication for both patient and surgeon. Non-operative treatments for the stiff TKA include shoe lift in contralateral limb, stationery bicycle with elevated seat position, extension bracing, topical application of hand-held instruments to areas of soft tissue-dysfunction by a trained physical therapist over several outpatient sessions, and use of a low load stretch device. Manipulation under anesthesia is indicated in patients after TKA having less than 90 degrees ROM after 6 weeks, with no progression or regression in ROM. Other operative treatments range from a downsizing exchange of the polyethylene bearing to revision with a constrained device and low-dose irradiation in cases of severe arthrofibrosis.

Introduction

Persistent pain after medial unicompartmental knee arthroplasty (UKA) is a prevailing reason for revision to total knee arthroplasty (TKA). Many of these pathologies can be addressed arthroscopically. The purpose of this study is to examine the outcomes of patients who undergo an arthroscopy for any reason after medial UKA.

The use of short femoral components in primary total hip arthroplasty (THA) represents an attractive option. Advocates tout bone preservation and ease of use in less invasive surgical approaches. In 2006 we adopted the concept and have had experience with over 5,700 short, tapered, titanium, porous plasma-sprayed stems in patients undergoing primary THA. The plasma-sprayed portion of this stem is similar to the longer, standard length TaperLoc stem, with shortening resulting from a 3 cm reduction in length of the distal portion of the implant. However, the proximal aspect maintains the same flat, tapered wedge proximal geometry as the standard stem. During insertion in some femurs it was noted that distal canal fill occurred preferentially to proximal canal fill. This required distal broaching in order to accommodate a larger stem. In an effort to avoid this clinical situation and to improve the gradual off-loading that is the goal of a tapered geometry, the design was modified in 2011 to reduce the profile of the component. Other modifications include a lower caput-collum-diaphyseal (CCD) angle to enhance horizontal offset restoration without increasing leg length, width sizing from 5–18 mm in 1 mm increments, and polished neck flats to increase range of motion. Undoubtedly, porous plasma sprayed tapered titanium stems are successful in primary THA. Short stems can better accommodate proximal-distal femoral mismatch, particularly in hips with a large metaphysis and a narrow diaphysis, hips with an excessively bowed femur, and hips with severe deformity such as that encountered with developmental dysplasia and post-traumatic arthritis. Short stems violate less femoral bone stock, allowing for more favorable conditions should revision surgery become necessary. The concept of a short stem is appealing to patients, who perceive it as less invasive. In addition, short stems facilitate shorter incision surgery and operative approaches such as the muscle-sparing anterior supine intermuscular. Increased canal fill has been associated with distal cortical hypertrophy. Reducing the distal portion of the stem has reduced the incidence of distal canal fill, and allows for placement of a slightly larger implant.

Converting UKA to TKA can be difficult, and specialised techniques are needed. Issues include bone loss, joint line approximation, sizing, and rotation. Determining the complexity of conversion pre-operatively helps predict the need for augmentation, grafting, stems, or constraint.

In a 2009 study from our center, 50 UKA revised to TKA (1997–2007) were reviewed: 9 implants (18%) were modular fixed-bearing, 4 (8%) were metal-backed nonmodular fixed-bearing, 8 (16%) were resurfacing onlay, 10 (20%) were all-polyethylene step-cut, and 19 (38%) were mobile bearing designs; 5 knees (10%) failed due to infection, 5 (10%) due to wear and/or instability, 10 (20%) for pain or progression of arthritis, 8 (16%) for tibial fracture or severe subsidence, and 22 (44%) due to loosening of either one or both components. Insert thickness was no different between implants (P=0.23) or failure modes (P=0.27). Stemmed component use was most frequent with nonmodular components (50%), all-polyethylene step-cut implants (44%), and modular fixed-bearing implants (33%; P=0.40). Stem use was highest in tibial fracture (86%; P=0.002). Augment use was highest among all-polyethylene step-cut implants (all-polyethylene, 56%; metal-backed, 50%; modular fixed-bearing, 33%; P=0.01). Augmentation use was highest in fracture (86%) and infection (67%), with a significant difference noted between failure modes (P=0.003). Failure of nonmodular all-polyethylene step-cut devices was more complex than resurfacing or mobile bearing. Failure mode was predictive of complexity. Reestablishing the joint line, ligamentous balance, and durable fixation are critical to assuring a primary outcome.

In a 2013 multicenter study of 3 institutions including ours, a total of 175 revisions of medial UKA in 168 patients (81 males, 87 females; average age of 66 years) performed from 1995 to 2009 with a minimum of 2-year clinical follow-up were reviewed. The average time from UKA to revision TKA was 71.5 months (range: 2 months to 262 months). The four most common reasons for failure of the UKA were femoral or tibial loosening (55%), progressive arthritis of the lateral or patellofemoral joints (34%), polyethylene failure (4%) and infection (3%). Mean follow-up after revision was 75 months. Nine of 175 knees (4.5%) were subsequently revised at an average of 48 months (range 6 months to 123 months.) The rate of revision was 1.23 revisions per 100 observed component years. The average Knee Society pain and function score increased to 75 and 66, respectively. In the present series, the re-revision rate after revision TKA from UKA was 4.5 % at an average of 75 months or 1.2 revisions per 100 observed component years.

In a current study from our center, 174 patients (180 UKA) underwent revision procedures (1996–2017). Most prevalent indications for revision were aseptic loosening (45%) arthritic progression (17%) and tibial collapse (13%). At 4 years mean follow-up, 5 knees (2.8%) have required re-revision involving any part, which is similar to what we recently reported at 5.5 years in a group of patients who underwent primary TKA (6 of 189; 3.2%), and much lower than what we observed at 6.0 years in a recent report of patients who underwent aseptic revision TKA (35 of 278; 12.6%).

Compared to published individual institution and national registry data, re-revision of a failed UKA is equivalent to revision rates of primary TKA and substantially better than re-revision rates of revision TKA. These data should be used to counsel patients undergoing revision UKA to TKA.

Bi-cruciate-retaining (BCR) total knee arthroplasty (TKA), which retains both the anterior (ACL) and posterior cruciate (PCL) ligaments, serves as an alternative to the traditional TKA procedure. Despite the difficulty of ensuring the structural integrity of the prosthesis, the BCR TKA can yield improved patient outcomes such as range of motion, kinematics, and even the survivorship of the implant. When possible, BCR TKA can and should be considered as a viable option to treat end-stage arthritis of the knee. Reconsidering the frequency of the BCR TKA is necessary for several reasons. Patient outcomes following BCR TKA are similar to outcomes for mobile-bearing UKA. Patients with an intact ACL do better with preservation (UKA or BCR TKA) of the ACL. The corollary is also true that removing an intact ACL at the time of arthroplasty has worse outcomes than traditional TKA in patients with an absent ACL. Reported outcomes of BCR TKA include more normal knee function, excellent prosthetic survivorship, and greater patient satisfaction. The BCR TKA may provide a missing link in the continuum of constraint for primary knee arthroplasty.

Many early BCR designs fell out of favor because of high rates of prosthetic loosening, and because the procedure was more technically demanding than that of highly successful ACL-sacrificing TKA devices. Recently there has been a reemergence of the BCR arthroplasty concept with improvements in design. By retaining both the ACL and PCL, BCR TKA patients show more normal knee function and flexibility due to anterior stability and replication of the physiological tension in the ACL. Modern BCR TKA models have improved upon early designs but are limited in use mainly due to the lack of an optimal prosthesis design and the relative difficulty of the surgical procedure.

Bi-cruciate-retaining TKA is a viable procedure if an appropriate femorotibial gap can be created to mimic physiological tension of the ACL and PCL. In terms of the surgical technique, the procedure begins with femoral preparation to facilitate tibial preparation. Distal femoral resection is performed first taking care to avoid damage to the ACL. Femoral preparation is then completed with a four-in-one guide that incorporates a protector to ensure the ACL is not resected. Good exposure is essential to tibial preparation, which is the critical part of the procedure and involves several steps of setting the depth of resection, and making accurate cuts to protect the tibial eminence island of bone and set tibial component rotation. The medial and lateral tibial cuts must be absolutely parallel. Precise cement technique is required for the tibial baseplate, and care must be taken when trialing the dual bearings.

Normal kinematics are preserved when both the ACL and PCL remain intact. Bi-cruciate-retaining TKA knees have been shown to restore more normal kinematics and have better “feel” than traditional ACL-sacrificing TKA knees. Bilateral TKA patients with designs of both types prefer their BCR TKA to their ACL-sacrificing TKA more often than not. An intact ACL has been shown to be present in 60–80% of arthritic knees, further justifying the consideration to retain both cruciate ligaments during TKA. New materials and refined instrumentation and techniques have helped improve the viability of BCR TKA, which may represent an additional option in the continuum of constraint for knee arthroplasty.

Not all knee surgery cases are created equal is a maxim that holds true for both primary and revision scenarios. Complex cases involve patients presenting with compromised bone and/or soft tissue. For primary knees, these include cases with bony deformity or deficiency, severe malalignment, arthrofibrosis, ligamentous instability or contracture, prior fracture or trauma with or without failed fixation, prior hardware complicating component placement, or compromised extensor mechanism. In revision surgery, complex scenarios include cases compromised by bone loss, deterioration of the soft tissues and resulting instability, periprosthetic fracture, leg length discrepancy, infection, and more recently, hypersensitivity reactions. In this interactive session, a moderator and team of experts will discuss strategies for evaluation and management of a variety of challenging knee case scenarios.

The number one reason to consider large heads in total hip arthroplasty (THA) is for increased stability. Large diameter femoral heads substantially increase stability by virtue of increased range of motion and increased jump distance, which is the amount of displacement required to sublux the head out of the socket. Prevention is the best means for reducing dislocation, with requisites for stability being appropriate component position, restoration of leg length, and restoration of offset.

In a review from our center studying the frequency of dislocation with small diameter femoral heads (≤32 mm) in 1262 patients (1518 hips) who underwent primary THA performed via a direct lateral approach, we observed a dislocation rate of 0.8% (12 of 1518). In a subsequent study of 1748 patients (2020 hips) who underwent primary THA at our center with large diameter heads (mean 43 mm, range 36–60 mm), we observed a substantially lower 0.04% frequency of dislocation (one of 2010) at a mean followup of 2.6 years.

Our findings have been echoed in studies from several other centers. Howie et al. reported a prospective controlled trial of 644 low risk patients undergoing primary or revision THA randomised to receive either a 36 mm or 28 mm metal head articulated on highly crosslinked polyethylene. They observed significantly lower frequency of frequency of dislocation with 36 mm heads both overall (1.3%, 4 of 299 versus 5.4%, 17 of 216 with 28 mm heads, p=0.012) and in primary use (0.8%, 2 of 258 versus 4.4%, 12 of 275 with 28 mm heads, p=0.024), and a similar trend in their smaller groups of revision patients (5%, 2 of 41, versus 12%, 5 of 41 with 28 mm heads, p=0.273).

Lachiewicz and Soileau reported on early and late dislocation with 36- and 40 mm heads in 112 patients (122 hips) at presumed high risk for dislocation who underwent primary THA. Risk factors were age >75 for 80 hips, proximal femur fracture for 18, history of contralateral dislocation for 2, history of alcohol abuse in 2, large acetabulum (>60 mm) in 6, and other reasons in 14. Early dislocation (<1 year) occurred in 4% (5 of 122), all with 36 mm heads. Late dislocation (>5 years) did not occur in any of the 74 patients with followup beyond 5 years.

Stroh et al. compared 225 patients (248 hips) treated with THA using small diameter heads (<36 mm) to 501 patients (559 hips) treated with THA using large diameter heads (≥36 mm). There were no dislocations with large diameter heads compared with 1.8% (10 of 559) with small diameter heads.

Allen et al. studied whether or not large femoral heads improve functional outcome after primary THA via the posterior approach in 726 patients. There were 399 done with small heads (<36 mm), 254 with medium heads (36 mm), and 73 with large heads (>36 mm), analyzed pre-operatively, at 6 months, and at 12 months. The authors could not find a correlation between increasing head size and improved function at one year, but observed that dislocation was reduced with large diameter heads.

Optimization of hip biomechanics via proper surgical technique, component position, and restoration of leg length and offset are mandatory in total hip arthroplasty. Large heads enhance stability by increasing range of motion prior to impingement and enhancing jump stability.

Total hip arthroplasty (THA) performed in patients aged 60 years and younger requires several decades of implant use under increased activity demands. Implant longevity and stable fixation are necessary for 30 or more years. The search for the optimal bearing combination for use in younger, high demand patients presents a challenge for orthopaedic surgeons as they consider the pros and cons of each material and interaction. A recent U.S. study of implant utilization trends that included 174 hospitals and 105,000 THA between 2001 and 2012 found that in 2012 93% of THA were cementless and 35% of THA bearings were ceramic-on-highly crosslinked polyethylene (HXLPE). Another recent article used the Nationwide Inpatient Sample from 2009 to 2012 to study bearing usage trends in 9265 primary THA in patients 30 years old or younger. The researchers observed ceramic-on-polyethylene as the most commonly bearing surface, used in 36% of patients, and which represented an increase from an earlier study of extremely young patients undergoing primary THA between 2006 to 2009, use of so-called hard-on-hard bearings decreased. Benefits of ceramic-on-HXLPE bearings are that unlike metal-on-polyethylene and metal-on-metal combinations, taperosis and adverse reactions to metal debris are non-existent. Ceramic-on-polyethylene is forgiving, it is an extremely low wear couple, it is the current presenter's bearing of choice in high demand patients, and it is a good option in the scenario of revision of failed metal-on-metal or for taperosis. Advantages to bulk ceramics are: extremely hard and scratch resistant to third body wear, not damaged by instruments and repositioning, excellent wettability, extreme low wear against itself with no known pathogenic reaction to ceramic particles, inherently stable with no oxidation or aging effect, no corrosion, safe in terms of metal ion release, no known risk of hypersensitivity or allergy, and no concerns about biological reaction. Biolox® (Ceramtec AG; Plochingen, Germany) ceramics have been available since 1974, with fourth generation Biolox® Delta introduced in 2003. Extensive clinical experience includes over 1630 published studies with over 12 million Biolox® components implanted with almost every available hip system. Two recent meta-analyses studies of randomised controlled trials comparing ceramic-on-ceramic to ceramic-on-polyethylene found significantly higher linear wear in ceramic-on-polyethylene but higher incidences of noise and fracture in ceramic-on-ceramic THA. There were no differences in revision, function, dislocation, osteolysis or loosening. A recent meta-analysis review of randomised controlled trials reporting survivorship of ceramic-on-ceramic, ceramic-on-HXLPE, and metal-on-HXLPE found no difference among bearing surfaces in risk of revision after primary THA in patients younger than 65. Risk ratio for revision was 0.65 (p=0.50) between ceramic-on-ceramic and ceramic-on-HXLPE, and 0.40 (p=0.34) between ceramic-on-ceramic and metal-on-HXLPE. A recent study of ceramic-on-HXLPE bearings for 130 cementless THA in 119 patients younger than 50 years at mean follow-up of 8.3 years (range, 7–9) reported a mean post-operative Harris hip score of 94, UCLA activity score of 8.1, no acetabular revisions, no osteolysis, no head or liner fracture, and 0.022 ± 0.003 mean annual penetration rate of the femoral head. While longer follow-up is necessary, ceramic-on-HXLPE bearings are an attractive option in younger, high demand patients undergoing primary THA.

The number one reason to consider large heads in total hip arthroplasty (THA) is for increased stability. Large diameter femoral heads substantially increase stability by virtue of increased range of motion and increased jump distance, which is the amount of displacement required to sublux the head out of the socket. Prevention is the best means for reducing dislocation, with requisites for stability being appropriate component position, restoration of leg length, and restoration of offset.

In a review from our center studying the frequency of dislocation with small diameter femoral heads (≤32 mm) in 1262 patients (1518 hips) who underwent primary THA performed via a direct lateral approach, we observed a dislocation rate of 0.8% (12 of 1518). In a subsequent study of 1748 patients (2020 hips) who underwent primary THA at our center with large diameter heads (mean 43 mm, range 36–60 mm), we observed a substantially lower 0.04% frequency of dislocation (one of 2010) at a mean followup of 2.6 years.

Our findings have been echoed in studies from several other centers. Howie et al. reported a prospective controlled trial of 644 low risk patients undergoing primary or revision THA randomised to receive either a 36 mm or 28 mm metal head articulated on highly crosslinked polyethylene. They observed significantly lower frequency of frequency of dislocation with 36 mm heads both overall (1.3%, 4 of 299 versus 5.4%, 17 of 216 with 28 mm heads, p=0.012) and in primary use (0.8%, 2 of 258 versus 4.4%, 12 of 275 with 28 mm heads, p=0.024), and a similar trend in their smaller groups of revision patients (5%, 2 of 41 versus 12%, 5 of 41 with 28 mm heads, p=0.273).

Lachiewicz and Soileau reported on early and late dislocation with 36- and 40 mm heads in 112 patients (122 hips) at presumed high risk for dislocation who underwent primary THA. Risk factors were age >75 for 80 hips, proximal femur fracture for 18, history of contralateral dislocation for 2, history of alcohol abuse in 2, large acetabulum (>60 mm) in 6, and other reasons in 14. Early dislocation (<1 year) occurred in 4% (5 of 122), all with 36 mm heads. Late dislocation (>5 years) did not occur in any of the 74 patients with follow up beyond 5 years.

Stroh et al. compared 225 patients (248 hips) treated with THA using small diameter heads (<36 mm) to 501 patients (559 hips) treated with THA using large diameter heads (≥36 mm). There were no dislocations with large diameter heads compared with 1.8% (10 of 559) with small diameter heads.

Allen et al. studied whether or not large femoral heads improve functional outcome after primary THA via the posterior approach in 726 patients. There were 399 done with small heads (<36 mm), 254 with medium heads (36 mm), and 73 with large heads (>36 mm), analyzed preoperatively, at 6 months, and at 12 months. The authors could not find a correlation between increasing head size and improved function at one year, but observed that dislocation was reduced with large diameter heads.

Optimization of hip biomechanics via proper surgical technique, component position, and restoration of leg length and offset are mandatory in total hip arthroplasty. Large heads enhance stability by increasing range of motion prior to impingement and enhancing jump stability.

Patient specific instruments have been developed in response to the conundrum of limited accuracy of intramedullary and extramedullary alignment guides and chaos caused by computer assisted orthopaedic surgery. This technology facilitates preoperative planning by providing the surgeon with a three dimensional (3-D) anatomical reconstruction of the knee, thereby improving the surgeon's understanding of the preoperative pathology. Intramedullary canal penetration of the femur and tibia is unnecessary, and consequently, any potential for fat emboli is eliminated. Component position and alignment are improved with a decrease in the number of outliers. Patient specific instruments utilise detailed magnetic resonance imaging (MRI) or computed tomography (CT) scans of the patient's knee with additional images from the hip and ankle for determination of critical landmarks. From these studies a 3-D model of the patient's knee is created and with integration of rapid prototyping technology, guides are created to apply to the patient's native anatomy to direct the placement of the cutting jigs and ultimately the placement of the components.

The steps in considering utilization of patient specific guides are as follows: 1) the surgeon determines that the patient is a candidate for TKA, 2) an MRI or CT scan is obtained at an approved facility in accordance with a specific protocol, 3) the MRI or CT is forwarded to the manufacturer, 4) the manufacturer creates the 3-D reconstructions, anatomical landmarks are identified, implant size is determined, and ultimately femoral and tibial component implant placement is determined via an algorithm, 4) the surgical plan is executed, 5) the physician reviews and modifies or approves the plan, 6) the guides are then produced via rapid prototyping technology and delivered to the hospital for the surgical procedure.

Guides generated from MRIs are designed to uniquely register on cartilage surface whereas guides produced from CT scans must register on bony anatomy. There are currently two types of guides produced: those which register on the femur and tibia and allow for the placement of pins to accommodate the standard resection blocks; and those produced by some manufacturers which accommodate the saw blade and therefore are a combination of resection and pin guides.

The utilization of patient-specific positioning guides in TKA has several benefits. They facilitate preoperative planning, obviate the need for violation of the intramedullary canals, reduce operating times and improve OR efficiency, decrease instrumentation requirements and thereby reduce potential for perioperative contamination. They are easier to use than computer navigation with no capital equipment purchase and no significant learning curve. Most importantly, patient-specific guides facilitate accurate component position and alignment, which ultimately has been shown to enhance long-term survivorship in total knee arthroplasty.

The surgical approach that is adequate for a primary total hip replacement may need to be modified to achieve a more extensile exposure as required for the revision procedure. A straightforward revision total hip replacement procedure can become quite complex when implant removal is attempted without adequate skill, instrumentation, or exposure. The most commonly used approaches in total hip replacement revision surgery are the transtrochanteric, posterolateral, and anterolateral. Although the effects of these approaches on the long-term clinical survival of the prosthetic composite are not completely clear, surgical approach does affect dislocation rates, trochanteric nonunion rates, and other indicators of clinical success.

Transtrochanteric Approach - Three variations of the transtrochanteric approach exist: A) The classic Charnley trochanteric approach was popularised by virtue of its use in primary total hip arthroplasty (THA) and, therefore, was easily applied to revision THA. This approach allows excellent visualization of the lateral shaft of the femur, thus enhancing implant and cement removal. However, the classic Charnley approach is associated with a high incidence of trochanteric nonunion. Reattachment of the atrophied trochanteric fragment often requires adjunct fixation such as cables, hooks, or bolts. These devices can subsequently break, migrate, or generate particulate debris which, in turn, is capable of producing extensive granuloma. B) The trochanteric slide is accomplished by an anteromedial inclination of the osteotomy, thus providing a more stable interface for reattachment. The trochanteric slide offers the advantage of maintaining muscle continuity. The disadvantage of this technique is decreased visualization of the acetabulum. Adjunct fixation of the trochanter is also required with this approach. C) By creating a 6 cm to 12 cm distal extension to the trochanteric fragment, a large lateral window is developed which enhances both prosthesis and cement removal. Subsequently, trochanteric fixation is enhanced because the extended fragment increases the surface area available for fixation. Because the extended trochanteric osteotomy requires a larger bone resection, proximal femoral bone stock can be compromised. As a result, proximal prosthetic support with a tapered device can force the trochanteric fragment laterally, increasing the likelihood of nonunion. When an extended trochanteric osteotomy is used, the patient's postoperative physical therapy and rehabilitation course should be modified to protect the healing trochanteric fragment.

Posterolateral Surgical Approach is used commonly in revision THA. The technique is popular because it is used widely for endoprosthetic replacement in the treatment of subcapital fractures. Also, the posterolateral approach is quite popular for primary THA. This approach has the advantage of maintaining the integrity of the abductor mechanism. Although femoral exposure is adequate, acetabular exposure can be limited. Also, this approach is associated with an increased incidence of dislocation. Another concern is its close proximity to the sciatic nerve, thus predisposing the patient to the risk of nerve injury.

Anterolateral Surgical Approach has the advantage of improved visualization of the acetabulum and femur without the attending trochanteric complications and proximity to the sciatic nerve. This approach is associated with a low incidence of dislocation. However, the abductor muscle is divided or split and, therefore, abductor dysfunction can occur post-operatively. There also can be an increased incidence of heterotopic ossification, but it avoids the problem of trochanteric nonunion.

Not all total hip arthroplasty cases are created equal is a maxim that holds true for both primary and revision scenarios. Complex cases involve patients presenting with compromised bone and/or soft tissue. For primary cases, these include hips with dysplasia, ankylosis, deformed proximal femora, protrusio acetabuli, prior hip fracture with or without failed fixation, previous bony procedures, or neuromuscular conditions. In revision surgery, complex scenarios include cases compromised by bone loss, deterioration of the soft tissues and resulting in dislocation and instability, peri-prosthetic fracture, leg length discrepancy, infection, and more recently, hypersensitivity reactions. Meticulous surgical technique including component placement is essential. In this interactive session, a moderator and team of experts will discuss strategies for evaluation and management of a variety of challenging hip case scenarios.

Converting UKA to TKA can be difficult, and specialised techniques are needed. Issues include bone loss, joint line approximation, sizing, and rotation. Determining the complexity of conversion pre-operatively helps predict the need for augmentation, grafting, stems, or constraint.

In a 2009 study from our center, 50 UKA revised to TKA (1997–2007) were reviewed: 9 implants (18%) were modular fixed-bearing, 4 (8%) were metal-backed nonmodular fixed-bearing, 8 (16%) were resurfacing onlay, 10 (20%) were all-polyethylene step-cut, and 19 (38%) were mobile bearing designs; 5 knees (10%) failed due to infection, 5 (10%) due to wear and/or instability, 10 (20%) for pain or progression of arthritis, 8 (16%) for tibial fracture or severe subsidence, and 22 (44%) due to loosening of either one or both components. Insert thickness was no different between implants (P=0.23) or failure modes (P=0.27). Stemmed component use was most frequent with nonmodular components (50%), all-polyethylene step-cut implants (44%), and modular fixed-bearing implants (33%; P=0.40). Stem use was highest in tibial fracture (86%; P=0.002). Augment use was highest among all-polyethylene step-cut implants (all-polyethylene, 56%; metal-backed, 50%; modular fixed-bearing, 33%; P=0.01). Augmentation use was highest in fracture (86%) and infection (67%), with a significant difference noted between failure modes (P=0.003). Failure of nonmodular all-polyethylene step-cut devices was more complex than resurfacing or mobile bearing. Failure mode was predictive of complexity. Reestablishing the joint line, ligamentous balance, and durable fixation are critical to assuring a primary outcome.

In a 2013 multicenter study of 3 institutions including ours, a total of 175 revisions of medial UKA in 168 patients (81 males, 87 females; average age of 66 years) performed from 1995 to 2009 with a minimum of 2-year clinical follow-up were reviewed. The average time from UKA to revision TKA was 71.5 months (range 2 months to 262 months). The four most common reasons for failure of the UKA were femoral or tibial loosening (55%), progressive arthritis of the lateral or patellofemoral joints (34%), polyethylene failure (4%) and infection (3%). Mean follow-up after revision was 75 months. Nine of 175 knees (4.5%) were subsequently revised at an average of 48 months (range 6 months to 123 months). The rate of revision was 1.23 revisions per 100 observed component years. The average Knee Society pain and function score increased to 75 and 66, respectively. In the present series, the re-revision rate after revision TKA from UKA was 4.5% at an average of 75 months or 1.2 revisions per 100 observed component years. Compared to published individual institution and national registry data, re-revision of a failed UKA is equivalent to revision rates of primary TKA and substantially better than re-revision rates of revision TKA. These data should be used to counsel patients undergoing revision UKA to TKA.

When dealing with the patella in total knee arthroplasty (TKA) there are three philosophies. Some advocate resurfacing in all cases, others do not resurface, and a third group selectively resurfaces the patella. The literature does not offer one clear and consistent message on the topic. Treatment of the patella and the ultimate result is multifactorial. Factors include the patient, surgical technique, and implant design. With respect to the patient, inflammatory versus non-inflammatory arthritis, pre-operative presence or absence of anterior knee pain, age, sex, height, weight, and BMI affect results of TKA. Surgical technique steps to enhance the patellofemoral articulation include: 1) Restore the mechanical axis to facilitate patellofemoral tracking. 2) Select the appropriate femoral component size with respect to the AP dimension of the femur. 3) When performing anterior chamfer resection, measure the amount of bone removed in the center of the resection and compare to the prosthesis. Do not overstuff the patellofemoral articulation by taking an inadequate amount of bone. 4) Rotationally align the femur appropriately using a combination of the AP axis, the transepicondylar axis, the posterior condylar axis, and the tibial shaft axis. 5) If faced with whether to medialise or lateralise the femoral component, always lateralise. This will enhance patellofemoral tracking. 6) When resurfacing the patella, only evert the patella after all other bony resections have been performed. Remove peripheral osteophytes and measure the thickness of the patella prior to resection. Make every effort to leave at least 15 mm of bone and never leave less than 13 mm. 7) Resect the patella. The presenter prefers a freehand technique using the insertions of the patellar tendon and quadriceps tendon as a guide, sawing from inferior to superior, then from medial to lateral to ensure a smooth, flat, symmetrical resection. Medialise the patellar component and measure the thickness of reconstruction. 8) When not resurfacing the patella, surgeons generally remove all the peripheral osteophytes, and some perform denervation using electrocautery around the perimeter. 9) Determine appropriate patellofemoral tracking only after the tourniquet is released. 10) Close the knee in flexion so as not to tether the soft tissues about the patella and the extensor. With or without patellar resurfacing, implant design plays in important role in minimizing patellofemoral complications. Newer designs feature a so-called “swept back” femur in which the chamfer resection is deepened, and patellofemoral overstuffing is minimised. Lateralizing the trochlear groove on the anterior flange, orienting it in valgus alignment, and gradually transitioning to midline have improved patellofemoral tracking. Extending the trochlear groove as far as possible into the tibiofemoral articulation has decreased patellofemoral crepitation and patellar clunk in posterior stabilised designs. With respect to the tibial component, providing patellar relief anteriorly in the tibial polyethylene has facilitated range of motion and reduced patellar impingement in deep flexion. On the patella side, the all-polyethylene patella remains the gold standard. While data exist to support all three viewpoints in the treatment of the patella in TKA, it is the presenter's opinion that the overwhelming data support patella resurfacing at the time of primary TKA. It is clear from the literature that the status of the patellofemoral articulation following TKA is multifactorial. Surgical technique and implant design are key to a well-functioning patellofemoral articulation. Pain is the primary reason patients seek to undergo TKA. Since our primary goal is to relieve pain, and there has been a higher incidence of anterior knee pain reported without patellar resurfacing, why not resurface the patella?

We perform the direct approach using a standard radiolucent operative table with extender at the foot, and the assistance of fluoroscopy. The patient is positioned supine with the pubic symphysis aligned at the table break. The anterior superior iliac spine (ASIS) and center of the knee are marked, and a line drawn between. The incision commences proximally from two finger breadths distal and two finger breadths lateral to the ASIS, and extends distally 8–10 cm. Using fluoroscopy, the anterior aspect femoral neck is located. The incision is placed over the lateral aspect of the greater trochanter, which avoids the lateral femoral cutaneous nerve. The tensor fascia lata is identified, which has a distinctive purple hue, and dissected free from the intermuscular septum lateral to the sartorius and the rectus muscles. The deep, investing aponeurosis of the tensor fascia lata is split using a tonsil. Just below lie the lateral circumflex vessels, two veins and one artery, which must be either ligated or cauterised. A retractor is placed superior to the femoral neck over top of the superior hip capsule. A blunt, cobra-type retractor is then placed along the inferior femoral neck, deep to the rectus muscle and the rectus tendon. A sharp retractor is then used to peel the rectus off from the anterior capsule and placed over the anterior rim of the acetabulum. An anterior capsulectomy is performed. A saw blade is positioned for femoral neck resection and confirmed with fluoroscopy. After resection, acetabular retractors are placed, the socket is reamed, the cup is placed, and position confirmed with fluoroscopy. Turning to the femoral side, the surgeon palpates underneath and around the tensor, around the lateral aspect of the femur, proximal to the gluteus maximus tendon, and places a bone hook around the proximal femur. Femoral preparation and stem insertion require maneuvering the table and adjusting the patient position. The table is “jack-knifed” by lowering the foot of the table to approximately 45 degrees and placing the bed into approximately 15 degrees of Trendelenburg. The contralateral well leg is placed on the padded Mayo stand. A table-mounted femur elevator is attached to the bed, requiring a change in surgical gloves, and attached to the traction hook around the proximal femur. Gentle retraction is placed on the femur to tension the capsule. As the capsule is released the femur will begin to come up/out of the wound and into view. With increasing gentle retraction via the table-mounted hook, the femur is elevated. Simultaneously, the operative limb is externally rotated and adducted underneath the non-operative leg in a lazy “figure of 4” position by the assistant. The use of a “broach-only” stem design is preferred as direct straight reaming of the femur is difficult in most cases. Fluoroscopic images are obtained to confirm femoral implant positioning, offset, neck and leg length. A standardised rapid recovery hospitalization and rehabilitation protocol is used in all cases.

Not all total hip arthroplasty cases are created equal is a maxim that holds true for both primary and revision scenarios. Complex cases involve patients presenting with compromised bone and/or soft tissue. For primary cases, these include hips with dysplasia, ankylosis, deformed proximal femora, protrusio acetabuli, prior hip fracture with or without failed fixation, previous bony procedures, or neuromuscular conditions. In revision surgery, complex scenarios include cases compromised by bone loss, deterioration of the soft tissues and resulting instability, periprosthetic fracture, leg length discrepancy, infection, and more recently, hypersensitivity reactions. In this interactive session, a moderator and team of experts will discuss strategies for evaluation and management of a variety of challenging hip case scenarios.