The Knee
(1) Skin incisions(A) Reuse pre-existing longitudinal incisions(B) Avoid parallel incision with narrow based flap(C) Avoid triangles (tip necrosis)(D) Cross transverse incisions at 90°(E) Choose most lateral longitudinal incision (within reason)--Medial blood supply(F) Reuse most recent incisions(2) Sham Incisions(3) Medial vs Lateral Arthrotomy(4) Exposures(A) Proximal(1) Lateral release and...
Particle-induced bone resorption is currently recognized as a major concern in orthopaedics. While many materials, design, and procedural factors may contribute to the generation of particles in the joint space, ultra-high molecular weight polyethylene (UHMWPE) wear debris is routinely identified as a primary source.Research has shown that gamma radiation sterilization degraded UHMWPE by breaking...
1. Results of RBBH unicompartmental knee arthroplastyThornhill, Clark et al.: 1991 AAOS307 UKAs in 251 patientsmean age 66.2 years; 153 female/98 malemean f/up 4.2 years (range 2-9 years)90% pain relief13 knees revised (4.5%)wear--5 kneesprogression of disease--5 kneesloosening--2 kneessynovitis--1 knee2. Current indications for UKR 8-10% of patients with OA undergoing TKRtransition patient between...
When devising total joint replacements, the goal is to reduce wear debris generation while maximizing clinical performance factors such as pain-free articulation. A variety of geometric designs and a variety of component material combinations (e.g. metal/polymer, ceramic/polymer, and metal/metal) have been investigated as a means of achieving these goals. Surface modification techniques (e.g. ion...
I. OverviewA. Deep-vein thrombosis (DVT) and pulmonary emboli (PE) remain one of the most serious and common complication following orthopaedic surgeryII. Incidence of DVT and PE after total knee arthroplastyA. DVT--No prophylaxis1. Venographically detected DVT: 65-88%2. Proximal DVT: 3-20%B. DVT--With prophylaxis1. Aspirin: 41-73%2. Warfarin: 24-69%3. Pneumatic compression: 10-33%4. LMWH: 17-45%III...
When contact occurs between metal and polyethylene components, both surfaces deform, but the metal component deforms such a small amount compared to the polyethylene that it behaves like a rigid body compared to the polyethylene. Thus, when a knee joint is loaded, the polyethylene is squeezed between the rigid metal femoral component and the supporting material--bone, cement, or forced to conform...
The safety of tourniquets in routine arthroscopic and replacement surgery of the knee is questioned. A literature review of the local effects of tourniquet ischaemia reveals damage to muscles varying from ultramicroscopic cellular changes to massive rhabdomyolysis, damage to nerves varying from postoperative pain, minor dysaesthesia and temporary weakness to prolonged or permanent paralysis, damage...
Benefits of femoral component external rotationThe orientation of the anatomic joint line is approximately 3 degrees of varus relative to the transverse axis of the tibia. A 90 degree tibial resection results in more bone removal from the lateral compared to the medial tibial plateau. If equal amounts of bone are then removed from both the posterior medial and posterior lateral femoral condyles,...
IntroductionThe purpose of this paper was to evaluate a deep dished polyethylene insert design for posterior stabilization in total knee arthroplasty. Deficiency of the posterior cruciate ligament does not require any change in bone preparation or alteration of the femoral component and is bone sparing. Results of the first 100 ultracongruent inserts are reported.Method59 primary and 41 revised...
Inflammatory response to particulate debris has been identified as the primary cause of osteolysis in total knee replacement. If this debris is contained within the joint, its effect on the surrounding bone is minimized as in some cemented total hip replacements. In cases with an intact cement mantle, the osteolysis appears to proceed gradually along the bone-cement interface around the acetabular...
Fifty consecutive patients who presented to an Outpatient Physiotherapy Department with anterior knee pain were randomly allocated to management with the McConnell regimen or isometric quadriceps exercises and completed the treatment programme. In patients treated by the McConnell regimen, McConnell's critical test was elicited significantly less frequently at 60° after 7 days, and in all positions,...
In order to prospectively determine the longevity of the MacIntosh technique of anterior cruciate reconstruction, using a fascia lata graft, a consecutive series of 21 patients with severe symptoms of chronic instability were assessed. They were reviewed when their postoperative functional recovery had stabilised (mean 19.2 months) by using the Cincinnati score, a clinical assessment of laxity and...
Thick soft tissue and structures involved in the knee's function surround the knee thus hiding the underlying kinematics. This makes diagnosis of pathologies and analysis of biomechanics difficult. This study accurately quantifies the relative movement between skin and the underlying bone, via X-ray flouroscopy and a mathematical model, in the interest of improving non-invasive knee movement analysis...
The PCL plays an important role in addressing the forces generated in knees with most daily activities. The hamstrings produce a drawer force on the flexed knee. Andriacchi had shown that by maintaining the increased quadriceps lever arm with a stabilized posterior tibiofemoral contact axis, patients with PCL preserving arthroplasties function better with stair climbing. It has been proposed that...
I. Arthrofibrosis after total knee replacement usually occurs when the knee has poor range of motion preoperativelyA. Particularly a problem in revision knee surgery and reimplantation after treatment of the infected total knee.II. Management of the stiff knee postoperativelyA. Manipulation of the knee was performed in 25-30 percent of TKRB. Improved TKR design has led to improved range of motionC...
Infection remains one of the most severe threats to total knee arthroplasty (TKA). Treatment options include antibiotics, wash-out, surgical debridement, one-stage and two-stage exchange, resection arthroplasty, arthrodesis and amputation. Antibiotics alone and arthroscopic wash-out do not yield sufficient infection control. Surgical debridement and retention of the prosthesis can be useful in...
1. Indications-- Chronic pain in a patient who otherwise is not a candidate for TKR:-- gross knee instability-- best indication: knee sepsis, especially following total knee arthroplasty2. Goals-- osseous union yielding a stable knee-- painless function-- eradication of infection3. Problems and pitfalls-- Difficulty in obtaining union-- malposition:-- excessive flexion/extension resulting in a long...
Observations made on retrieval total joint components provide valuable information for the clinician and the implant designer. This is true whether the components are removed for failure or if they are retrieved at autopsy from well-functioning joints. Retrieved components furnish direct evidence of the performance of the device design and of the materials from which it was fabricated. When retrieved...
Removal of failed total knee components requires one absolute essential: excellent exposure! Techniques for removal of implants, with preservation of the remaining bone stock, will universally fail without this essential element.The failed total knee is often associated with stiffness, which will make entrance into the joint challenging. The surgeon should first decide on the appropriate incision,...
John Charnley is considered the father of contemporary total hip replacement. Since his pioneering work, more than six million total hip replacements have been inserted worldwide. Although the benefits of total hip replacements seem self-evident, contemporary forces have prompted an examination of all common medical procedures. The cost of health care financing has become an issue in each country...