Surgical treatment for early osteoarthritis. Part II: allografts and concurrent procedures.

UNLABELLED: Young patients with early osteoarthritis (OA) represent a challenging population due to a combination of high functional demands and limited treatment options. Conservative measures such as injection and physical therapy can provide short-term pain relief but are only palliative in nature. Joint replacement, a successful procedure in the older population, is controversial in younger patients, who are less satisfied and experience higher failure rates. Therefore, while traditionally not indicated for the treatment of OA, cartilage repair has become a focus of increased interest due to its potential to provide pain relief and alter the progression of degenerative disease, with the hope of delaying or obviating the need for joint replacement. The field of cartilage repair is seeing the rapid development of new technologies that promise greater ease of application, less demanding rehabilitation and better outcomes. Concurrent procedures such as meniscal transplantation and osteotomy, however, remain of crucial importance to provide a normalized biomechanical environment for these new technologies. LEVEL OF EVIDENCE: Systematic review, Level II.

Biomechanical, structural, and biochemical indices of degenerative and osteoarthritic deterioration of adult human articular cartilage of the femoral condyle.

OBJECTIVE: To compare the tensile biomechanical properties of age-matched adult human knee articular cartilage exhibiting distinct stages of degenerative or osteoarthritic deterioration and to determine the relationships between tensile properties and biochemical and structural properties hypothesized to underlie functional biomechanical deterioration. METHODS: Age-matched articular cartilage samples, obtained from the lateral and medial femoral condyles (LFC and MFC), exhibited (1) minimal fibrillation, characteristic of normal aging (NLA), (2) overt fibrillation associated with degeneration (DGN), or (3) overt fibrillation associated with osteoarthritis (OA). DGN samples were from knees that exhibited degeneration but not osteophytes while OA samples were from fragments removed during total knee arthroplasty. Cartilage samples were analyzed for tensile properties, cell and matrix composition, and histopathological structure. RESULTS: Differences in tensile, compositional and surface structural properties were indicative of distinct stages of cartilage degeneration, early (OA) advanced (DGN) and late (OA) with early degenerative changes in NLA samples being more advanced in the MFC than the LFC, including higher surface fibrillation, lower intrinsic fluorescence, and lower mechanical integrity. The transition from early to advanced degeneration involved a diminution in mechanical function, surface integrity, and intrinsic fluorescence. The transition from advanced to late degeneration involved an increase in cartilage water content, an increase in degraded collagen, and loss of collagen. CONCLUSIONS: These results provide evidence of coordinated mechanical dysfunction, collagen network remodeling, and surface fibrillation. Even in the cartilage of knees exhibiting overt fibrillation but not extensive erosions characteristic of clinical osteoarthritis, most features of advanced cartilage degeneration were present.

Continuous passive motion applied to whole joints stimulates chondrocyte biosynthesis of PRG4.

UNLABELLED: Continuous passive motion (CPM) is currently a part of patient rehabilitation regimens after a variety of orthopedic surgical procedures. While CPM can enhance the joint healing process, the direct effects of CPM on cartilage metabolism remain unknown. Recent in vivo and in vitro observations suggest that mechanical stimuli can regulate articular cartilage metabolism of proteoglycan 4 (PRG4), a putative lubricating and chondroprotective molecule found in synovial fluid and at the articular cartilage surface. OBJECTIVES: (1) Determine the topographical variation in intrinsic cartilage PRG4 secretion. (2) Apply a CPM device to whole joints in bioreactors and assess effects of CPM on PRG4 biosynthesis. METHODS: A bioreactor was developed to apply CPM to bovine stifle joints in vitro. Effects of 24h of CPM on PRG4 biosynthesis were determined. RESULTS: PRG4 secretion rate varied markedly over the joint surface. Rehabilitative joint motion applied in the form of CPM regulated PRG4 biosynthesis, in a manner dependent on the duty cycle of cartilage sliding against opposing tissues. Specifically, in certain regions of the femoral condyle that were continuously or intermittently sliding against meniscus and tibial cartilage during CPM, chondrocyte PRG4 synthesis was higher with CPM than without. CONCLUSIONS: Rehabilitative joint motion, applied in the form of CPM, stimulates chondrocyte PRG4 metabolism. The stimulation of PRG4 synthesis is one mechanism by which CPM may benefit cartilage and joint health in post-operative rehabilitation.

Expression and regulation of cryopyrin and related proteins in rheumatoid arthritis synovium.

BACKGROUND: Rheumatoid arthritis (RA) synovium is characterised by enhanced NF-kappaB activity and proinflammatory cytokines. Cryopyrin (CIAS-1, NALP-3, PYPAF-1) has been shown to regulate NF-kappaB and caspase-1 activation. OBJECTIVE: To study the expression of cryopyrin, its effector molecule ASC, and its putative antagonist pyrin in RA and osteoarthritis (OA) synovium, and the main two cellular constituents of synovial lining, cultured fibroblast-like synoviocytes (FLS) and macrophages. METHODS: FLS and macrophages were cultured in the presence of inflammatory mediators. Real time polymerase chain reaction was used to quantify message levels in synovial biopsy specimens and cells. In situ hybridisation was employed to localise expression of cryopyrin mRNA. RESULTS: Cryopyrin mRNA was raised in RA synovium and detected in both lining and sublining regions. FLS from RA and OA tissue expressed low baseline levels of cryopyrin transcripts that were induced by tumour necrosis factor alpha (TNFalpha). In contrast, macrophages differentiated in vitro expressed relatively high cryopyrin levels, which were further induced by TNFalpha, but not by interleukin 1beta. ASC mRNA levels were comparable in RA and OA tissue, FLS, and macrophages, and were depressed by TNFalpha in macrophages. Pyrin expression was higher in RA synovium than in OA tissue, and virtually undetectable in FLS but high in macrophages where it was unchanged by TNFalpha treatment. CONCLUSION: These results suggest that enhanced cryopyrin levels in RA synovium are due to a greater numbers of tissue macrophages, and demonstrate transcriptional regulation of cryopyrin in a chronic inflammatory disease.

Differences in mesenchymal tissue repair.

Variations in certain mesenchymal tissue healing processes are not widely recognized. The current review summarizes key differences in healing mechanisms and healing potential after injury to soft tissues having different healing outcomes.

Does implant selection affect outcome of revision knee arthroplasty?

We reviewed 139 consecutive femoral or tibial revision knee arthroplasties to determine if the outcome of revision knee arthroplasty using revision implant systems was superior to revisions using primary implant systems. Group 1 (n = 42) consisted of revisions performed with implants designed for primary total knee arthroplasty. Group 2 (n = 42) consisted of revisions performed with modified primary components. Group 3 (n = 55) consisted of revisions performed with components specifically designed for revision arthroplasty. The implant status was known in 123 of 139 knees at a mean follow-up of 7 years (range, 5-12 years). The implant-related failure rate, defined as reoperation requiring component revision or removal, was 26% for group 1, 14% for group 2, and 6% for group 3 (P<.05). Revision implants exhibited superior performance and durability despite their use in more difficult reconstructions. The improved longevity of revision implants justifies the evolution of modular revision components.

Shell osteochondral allografts of the knee: comparison of mr imaging findings and immunologic responses.

PURPOSE: To define the magnetic resonance (MR) imaging appearance of shell osteochondral allografts of the knee and compare the MR findings with antibody responses. MATERIALS AND METHODS: Thirty-six grafts were evaluated with a 1.5-T unit with T1-, intermediate-, and T2-weighted, and three-dimensional spoiled gradient-recalled MR imaging at 3, 6, 12, 24, and/or 36 months after surgery. Nineteen patients underwent imaging serially. Two osteoradiologists scored by consensus host marrow edema, thickness of graft-host interface, signal intensity of graft marrow, cyst formation, joint effusion, articular cartilage defects, and surface collapse. Patients were divided into antibody-positive (AP) (n = 11) and antibody-negative (AN) (n = 25) groups evenly distributed across the different time points on the basis of results of anti-human leukocyte antigen antibody screening. MR findings for the two groups were compared. RESULTS: AP patients demonstrated greater mean edema (P<.002), thicker interface (P<.03), and more abnormal graft marrow (P<.04) than AN patients, and they had a higher proportion of surface collapse (P<.03). CONCLUSION: Humoral immune responses were associated with more inflammation and less complete incorporation after allograft placement. MR imaging shows promise as a surrogate biomarker for success of shell osteochondral allograft implantation.

Polydioxanone biodegradable pins in the knee: MR imaging.

OBJECTIVE: Biodegradable solid implants have been developed as an alternative to metallic orthopedic fixation. In animal models, implants degrade within and are replaced by bone. This study documents the resorption of these devices in human patients with MR imaging. SUBJECTS AND METHODS: One hundred seventy-five 1.3-mm biodegradable pins made of polydioxanone were used to secure a total of 59 osteochondral allografts of the knee. Patients with the pins underwent scanning on a 1.5-T unit with 3.3- to 4-mm contiguous T1-weighted spin-echo (TR/TE, 600/15), fat-saturated proton density-weighted (3000/40), T2-weighted fast spin-echo (3000/63), and three-dimensional spoiled gradient-recalled (47/7; flip angle, 60 degrees ) sequences at 3, 6, 12, 24, or 36 months after surgery. Eighty-nine pins were imaged on multiple occasions. Two osteoradiologists interpreted the MR examinations. RESULTS: More than 80% of the pin channels were visible at 3 and at 6 months after surgery. By 24 months, only 20% of the pin channels were visible, with the remainder having been replaced by bone. At 3 months, nearly 40% of the pins were associated with adjacent marrow edema. Edema generally diminished, involving less than 20% of pins at later time points. Focal cartilage defects were evident at 32% of the pin insertion sites during the first 6 months, but these defects were present in only 4% of the insertion sites thereafter. CONCLUSION: Biodegradable polydioxanone pins usually resorb completely by 24 months. Marrow edema, presumably representing inflammation related to pin resorption, is infrequent and tends to resolve. Cartilage defects related to pin placement heal spontaneously.

Osteochondral allograft transplantation.

Experience with fresh osteochondral allografting for cartilage defects in the knee now extends two decades. Clinical outcomes and basic scientific investigations have supported the theoretic basis for this procedure. At the University of California, San Diego, our experience has encouraged us to continue to offer this procedure as a primary treatment for both large and small articular cartilage defects in the young knee. The success rate of fresh osteochondral allografting, particularly in isolated femoral condylar defects, compares favorably with other presently available cartilage repair and resurfacing techniques. In our second hundred cases, which we are currently evaluating, failure of monopolar allografts has been exceedingly rare in short-term follow-up. Fresh osteochondral allografting also appears to be effective in treating larger osteochondral lesions, where there are few other attractive alternatives. Fresh osteochondral allografts can thus be used to treat a wide spectrum of articular pathology. Technical refinements, and improvement in our understanding of graft-host interaction, as well as chondrocyte biology, should continue to improve clinical results. Disadvantages of fresh osteochondral allografting include the relative paucity of donor tissue, complexities in procurement and handling, and the possibility of disease transmission through the transplantation of fresh tissue. At present, only institutions that have overcome these obstacles seem capable of routinely performing this type of articular cartilage transplantation. In the future, as tissue banking and cartilage storage technology advance, fresh allograft tissue may become more available, allowing more widespread use of fresh osteochondral allografting in the treatment of articular cartilage lesions.

4- to 10-year results with the anatomic modular total knee.

The outcome of 186 consecutive total knee arthroplasties performed with the Anatomic Modular Knee is reported. One hundred forty-two knees had followup of 4 to 10 years (mean, 6.9 years). Two knees required revision of all components, one because of infection and the other for instability. Seven patients underwent exchange of the modular tibial polyethylene insert at an average of 84 months postoperatively. The mean age of these seven patients at primary arthroplasty was 54 years. No implant showed clinical or radiographic evidence of loosening and there were no complications related to patellofemoral articulation. The revision rate of the femoral, tibial, and patellar components was two of 142 or 1.4%. The revision rate including exchange of the polyethylene insert was nine of 142 or 6.3%. This minimally constrained posterior cruciate retaining modular design performed well at intermediate followup. The absence of patellofemoral complications and aseptic loosening was notable. Wear related phenomena were the most common indications for reoperation and these occurred in younger, active individuals with relatively thin polyethylene bearings. The relative value of modular tibial inserts and the outcome of isolated polyethylene exchanges warrant additional study.

Long-term clinical consequences of stress-shielding after total hip arthroplasty without cement.

Remodeling of the femur, or so-called stress-shielding, was observed on the two-year postoperative radiographs of forty-eight (23 per cent) of 207 hips that were part of a consecutive, non-selected series of 223 hips that had had a primary arthroplasty with use of the anatomic medullary locking hip system. Three patients (three hips) died within ten years after the arthroplasty, leaving forty-four patients (forty-five hips) who had a minimum of ten years of clinical follow-up. At the time of the latest follow-up, thirty-eight patients (86 per cent) reported that they had either no or mild pain related to the hip, forty-two (95 per cent) had less pain than they had had preoperatively, and forty-one (93 per cent) were satisfied with the results of the arthroplasty. Two patients had a reoperation, but neither procedure involved the femoral component; specifically, one patient had a revision of a loose acetabular component and one had an exchange of a polyethylene liner. No femoral component was associated with clinical or radiographic evidence of loosening. Femoral osteolysis, confined to zones 1 and 7 of Gruen et al., was observed on the ten-year radiographs of four of the thirty-three hips for which such radiographs were available. Stress-shielding (defined as evidence of pronounced femoral bone-remodeling on the two-year radiographs) had not adversely affected the outcome for these four hips by the time of the latest follow-up. The findings regarding postoperative pain, function, and over-all satisfaction for the forty-four patients (forty-five hips) who were included in the present study were similar to those reported for our larger (parent) series of patients who had been managed with the anatomic medullary locking hip system and to those reported for a similar series of patients who were followed for 9.5 years after the insertion of a porous-coated anatomic prosthesis. In addition, the prevalence of acetabular and femoral osteolysis (four [12 per cent] of thirty-three hips) and that of revision of the femoral component (zero [0 per cent] of forty-five hips) were lower than those for our larger (parent) series (fifty-four [39 per cent] of 137 hips and three [1 per cent] of 201 hips, respectively) as well as those for the series of patients who had been managed with the porous-coated anatomic prosthesis (thirty-five [45 per cent] and four [5 per cent] of seventy-eight hips, respectively).

Bone remodeling around cementless hip implants.

Bone remodeling results from the adaptation of bone to the stresses that act upon it. The insertion of an endoprosthesis into a femur changes the stress distribution within the femur, causing the bone to remodel. In this paper, we show how radiographic bone remodeling changes can be used to determine implant fixation and how bone remodeling changes can be quantitated by using dual-energy x-ray absorptiometry analysis as well as computer-assisted videodensitometry.

In vivo effect of pressurization of polymethyl methacrylate bone-cement. Biomechanical and histologic analysis.

Sixteen goats underwent total hip arthroplasty, half with pressurized and half with unpressurized bone-cement. The animals underwent hemiarthroplasty of the contralateral hip immediately prior to sacrifice 6 weeks later. Samples were tested for interface strength and evaluated histologically. Pressurization of polymethyl methylacrylate improves the strength of the bone-cement interface in vivo, as well as in vitro. There is a regional variation in the strength of the bone-cement interface both in vivo and in vitro. The regional variation in the in vivo model is at least in part due to a biologic effect. Membranes forming at the bone-cement interface are usually fibrous and incomplete, allowing direct cement-to-bone contact. Membranes appear to be involved in the remodeling of bone. Polymethyl methacrylate causes significant necrosis of the cortex, with ensuing resorption of the cortical bone. There is a small, statistically insignificant trend toward increased resorption and decreased bone formation with pressurized cement. The amount of necrosis appears to be similar with pressurized and nonpressurized cement. Bone remodels to fill defects in the cement mantle.

Surface anatomy of the hand. The relationships between palmar skin creases and osseous anatomy.

Markers placed along palmar skin creases of 53 hands radiographically demonstrated creases superimposed on osseous anatomy. The distal and middle digital creases were found to be consistently proximal to associated interphalangeal joints by 7 to 8 mm and 2 to 3 mm, respectively. Proximal digital creases were consistently distal to associated metacarpophalangeal (MCP) joints by 14 to 20 mm. Distances between the distal transverse palmar crease and associated MCP joints were 6.8 to 10.3 mm. Distances between the proximal palmar crease and the associated MCP joints were 9.1 to 22.1 mm. Mean perpendicular distances between the distal wrist crease and center of selected carpal structures or joints were as follows: scaphoid, 0.7 mm; pisiform, 3.4 mm; lunate, 9.2 mm; hamate hook, 12.6 mm; ulnar styloid, 11.7 mm; trapeziometacarpal joint, 19.4 mm; radioscapholunate joint, 13.5 mm; and distal radioulnar joint, 21.1 mm. Quantification of these relationships should assist in hand examination and placement of surgical incisions and provide further insight into anatomic and functional relationships of the hand.

Changes in Resident Bacteria, pH, Sucrose, and Invert Sugar Levels in Sugarbeet Roots During Storage.

Stored sugarbeet roots began fermenting within 24 h after oxygen was depleted at 26 C when the resident bacterial populations increased dramatically. Most of the bacteria present after anaerobic storage for 7 days at 26 C could hydrolyze sucrose in vitro. Although pH and sucrose levels decreased and invert sugar levels increased with time in aerobic storage at 26 C, these processes were significantly accelerated in beets stored anaerobically at 26 C. Under oxygen-depleted storage conditions at 26 C, the sucrose content was almost completely lost after 21 days.

Microflora and invert sugars in juice from healthy tissue of stored sugarbeets.

Bacterial populations increased in juice of healthy tissue of sugarbeet roots stored at 5 C. Average counts showed a sixfold increase after 150 days of storage. Invert sugar levels increased over threefold in "American 4 Hybrid A" and remained fairly constant in "Mono-Hy D-2." The former cultivar also had significantly higher bacterial colony counts than the latter before 90 days of storage. Of 36 isolates identified, 16 were Pseudomonas spp. including P. chlororaphis; 6 Bacillus spp. including B. subtilis; 5 Arthrobacter spp. including A. globiformis; 4 yeasts; 2 Erwinia spp; 2 Flavobacterium spp. including F. aquatile; and Streptomyces longisporus. Isolates of all genera except S. longisporus were able to hydrolyze sucrose in vitro.