TOTAL HIP RESURFACING ARTHROPLASTY: THE ACTUAL ROLE
S. Zanasi, M. Pastina
Villa Erbosa Hospital, Gruppo San Donato, OrthopaedicsDept. Bologna, Italy
The hip surface replacement concept remains attractive because the femoral head and neck arepreserved, the femoral (thigh) bone is loaded in a more natural way, the large femoral shellenhances the stability and ROM of the surface replacement arthroplasty and prevents dislocation.Preservation of bone stock is especially attractive for young, active patients who are likely tooutlive their first hip arthroplasty operation and will have a new arthroplasty operation during theirlifetime. The theoretical advantages of the resurfacing metal-on-metal articulation are: no boneresection (total conservation of the femural head), recovery of normal ROM, less wear, less bonerebsorption, less leg length discrepancy and offset problems, an anatomical reconstruction, avoidingof "stress-shielding", maximal proprioceptive feedback, minimal risk for dislocation, easier revisionsurgery, normal femural loading.In particular the ReCapTM Femoral Resurfacing System is unique among femoral head resurfacingdevices. The implant design and surgical technique minimize the amount of resected bone andprovide intraoperative versatility. Competitive designs remove more bone circumferentially fromthe femoral head , which can increase the chance of notching the femoral neck, one of the reasonsfor component failure. The ReCapTM Femoral Resurfacing System utilizes anatomical geometriclimits to define a technique that removes only the bone necessary to apply a thin, yet durable, cobaltchrome, femoral head resurfacing component over the articulating surface.Should revision to total hip arthroplasty ever become necessary, revision to a total hip prosthesismay be as simple as preparing for, and implanting, primary hip implants. The femoral neck isresected and a traditional "primary" hip stem is put in place. Biomet’s ReCapTM FemoralResurfacing System is non-invasive to the femoral canal, reducing intraoperative blood loss, andleaving a virgin femoral canal should future total hip arthroplasty become necessary.On the basis of our experience (126 RHA reviwed from 6/2005 to 6/2008) in confront of worldwidecases series our indications for resurfacing are lightly more restrictive: mainly young, activepatients, usually male under 60 years of age and female under 50 years, who will meet also theother requirements for total hip replacement, i.e. severe limitation and stiffness in the hip joint. It isimportant that the patient does not have any risk factors that may increase the risk of failure of thesurface hip replacement operation. Such risk factors are: osteoporosis; head deformities of thefemoral head, where restoration of leg length and offset is not possible; previous operation on thehip, especially an operation that left the neck of the thighbone deformed; patients with bone cysts(voids) in the femoral heads and necks and patients with very small and /or severely deformed hipjoints. Further contraindications at total hip resurfacing and resorting to MIS THA with neckpreservation are: secondary hip arthritis due to trauma, Perthes disease, epifisiolysis, asepticnecrosis — Amstuz stage greater II - of femural head , reumatoid arthritis, head femural deformities.In ALL these cases a modular big ball head can be used with a stemmed femoral implant with thesame metal-on-metal properties as the total hip resurfacing implant, and big ball head advantages .Complications are mainly due to neck fracture: in the published reports about the modern surfacehip replacement this complication occurred in about 0.8 to 1.0% of all patients. In our yet selectedcases for hip resurfacing, neck fracture unfortunely occurred, without any documented cases ofimpingement, notching, malpositioning, in 5.5 % of the implants (7out of 126) . Usually it occurs within six months after surgery (6 out of 7 occurs within three ms after surgery); the first signs arepain. In some patients it occurs without a previous trauma. Theoretically a femoral neck fracturecan only occur with a poor technique or improper indications (elderly people — osteoporosis) but inour case we did not find other elements probably predisposing than fast and intensive recovery ofthe previous work requiring prolonged standing or setting, with complete weight bearing within 20days postop. Heterotopic ossifications are equally frequent as after total hip replacement: predisposed are samecategories of patients as the patients at risk after after total hip replacement: in our reviewed caseswe found only 9 cases out of 126, and all cases were confined within I to ll degree, according toBrooker.An other particular element to be underlined is the high blood levels of metal traces: the surfacereplacement shells have larger surfaces than conventional metal on metal total hip prostheses and,at least theoretically, they will produce more metallic particles and other corrosion products thanconventional metal on metal total hip prostheses. Consequently one may suppose higher levels ofthese metals in the blood and urine of patients with surface hip replacements. Our report showedthat patients with hip surface replacements had very high values of Chromium and Cobalt in theirblood and urine in the first year postop. These values, according to Jacobs studies (Jacobs 1996).were also 3 - 4 fold higher then the already high values of these metals in patients with metal onmetal total hip prostheses. Patients with bilateral surface replacements have had still higher serum& urine levels of these metals. These elevated values of trace metals were found in patients whohave had their surface replacement surgery less than two years ago. It is known that the wear ofmetal on metal surfaces is very high during the initial period. It may be that these very high serumlevels of the trace metals only reflect the initially high wear rates of metal on metal bearingcouples. Although the use of metal on metal bearing couples in the surface hip replacementeliminates the production of polyethylene particles, there is concern about the high bloodconcentrations of the metals that are part of the alloys used for fabrication of surface shells. Theimportance of these very high serum & urine levels of the trace metals for the development ofcancer is not known. (Merrit 1996). Patients with impairment of kidney iiinction (urea blood levelsand creatinin clearance levels too high) should not have modern surface hip replacement withmetal-on-metal shells.Finally the actual role of hip resurfacing according to our 8 ys longstanding cases series (last reviewfrom 2004 to 2008) should be to confine only to very young male and female people affected byprimitive and secondary OA, that is strongly motivated and strongly require for resurfacing and thatis learned on the possible complications that should take to revisiting the femoral component of theTHA.
METAL ON METAL TOTAL HIP RESURFACING ARTHROPLASTY WITHHIGHEST DIAMETER HEADS IMPLANT COMPONENT IN YOUNG PATIENTS
S. Zanasi, M. Pastina, F. Lenzi
Villa Erbosa Hospital, Gruppo San Donato, OrthopaedicsDept. Bologna, Italy
Encouraging results and new implant developments have allowed total hip replacement to beperformed in increasingly younger and more active patients. In young patients, however, outcomesare not comparable to those seen in older patients. The inflammatory reaction to polyethylene wearparticles is one of the main causes of aseptic loosening and subsequent revision surgery and canlimit the longevity of an arthroplasty in young and active patients. Even though ceramic femoralheads have been associated with lower in vivo polyethylene wear rates, which have been variableand up to 50% lower than with metallic heads metal—on-metal bearings have been reintroducedwith improved materials, design, and manufacturing . The most noteworthy advantages of the useof largest head size MOM THA include very low wear and subsequent osteolysis, increased rangeof motion to reduce the risk of impingement and luxation and the potential to monitor implantperformance by serial assessment of metal ion levels. Current metal-on-metal bearings are based oncobalt-chromitun-molybdenum alloys with varying carbon contents. Such bearings are self-polishing. Linear wear rates remain at the level of a few micron a year. These features seem toimprove clearly the tribology and longevity of the THR. In particular the recovery of the quitecomplete ROM and the excellent joint stability after emiresurfacing hip arthroplasty (big headeffect) could be one of the main factors favoring a high activity level compared to conventionalTHA, furtherly by limiting the episodes of dislocation and increasing the suction effect between thejoint components, allowing young patients sport activity too. It is nevertheless difficult to ascertainthe long-terrn effect of intense sports activity on the fixation of osteo-integrated implants (cups) andcemented components (femoral stem). Although the advantages of low wear and increased range ofmotion have made MOM THA an attractive bearing surface option, more widespread use of MOMbearing surfaces has been tempered with concern for increased metal ion levels and hypersensitivityreactions. All bearings have disadvantages, and a metal-on-metal bearing is no exception. Concernsexist regarding the generation of metal ions seen in the blood and urine of patients with metal-on-metal implants. These elevated metal ions have theoretical, although not proven, risks related tocarcinogenic and biologic concerns. Additionally, concerns exist regarding hypersensitivity,increased costs. Specific patient selection issues arise with metal-on-metal implants. The currentgeneration of implants has only early and mid—term results available, with no long-terrn series yetpublished. According to current knowledge, this metal-on-metal bearing still represent, with alumina-on-alumina and highly crosslinked PE, a competitive and comprehensive option to improveTHA longevity. The real pending problem concerns the frequency and above all the intensity ofmetal delayed hypersensitivity reaction and their potential effect on implant loosening. Therefore,although a metal-on-metal bearing may be considered a viable altemative to either polyethylene orceramic implants, outstanding and unresolved issues continue to exist with this bearing, as they dowith the altematives.
LARGE AND MASSIVE ROTATOR CUFF TEARS TREATMENT BY ORTHOADAPT
S. Zanasi, M. Pastina, F. Lenzi .
Villa Erbosa Hospital, Gruppo San Donato, OrthopaedicsDept, Bologna, Italy
Large rotator cuff tears, a common source of shoulder pathology, are often the cause of debilitatingshoulder pain, reduced shoulder function and compromised joint mechanics. Despite surgicaladvances, there is a high rate of recurrent tears ranging (20-70%) after surgical repair, particularlyfor chronic, large to massive cuff tears. The inability to obtain a high healing rate in these tears hasfueled investigation in the use of extracellular matrix (ECM) derived materials as a scaffolds forrotator cuff tendon repair and regeneration. Over the past few years, many biologic patches havebeen developed to augment repairs of large or complex tendon tears. These patches include bothallograft and xenografts. Regardless of their origins, these products are primarily composed ofpurified type I collagen. An extensive amount of basic science and preclinical models havedemonstrated that an ECM patch may offer improved healing rates with a biomechanical profilethat nearly reproduces the features of the native rotator cuff tendon. Many factors should beconsidered when choosing an augmentation patch including tissue origin, graft processing, cross-linking, clinical experience, and physical properties. The OrthADAPTTMBioimplant from PegasusBiologics, Inc. is a FDA cleared, decellularized, biologic scaffold that fortifies and promotes tissueingrowth. It is intended for the reinforcement, repair and reconstruction of soft tissue in orthopedicprocedures. The bioimplant is stabilized and sterilized using proprietary technologies which make itresistant to premature enzyme degradation, biocompatible and safe. Preclinical studies have shownthat the OrthADAPTBioimplant—FX integrates with host tissue by revascularizing and supportingthe remodeling cascade to lay down new collagen and provides a reliable scaffold throughout thehealing process.The OrthADAPT® Bioimplant is a highly organized Type I collagen scaffold that we have mainlyused for the reconstruction, augmentation, and reinforcement of rotator cuff soft tissue. Clinicalresults demonstrated that this bioimplant is an effective scaffold, does not produce any clinicallysignificant inflammatory responses and provides strength throughout the healing process for rapid,controlled remodeling at the implantation site. Excellent augmentation/reconstruction outcome ofthe rotator cuff tendon have been achieved in the reviewed 12 cases of largest and massive injury(type III, IV of Walch, grade 2,3 according to Mansat) : 6 month post-op MRI demonstratedcomplete continuity restoration of the 12 rotator cuff reconstructed using the OrthADAPT®bioimplant. At 6 months post—op all patients do very well, being pain-free, taking no medicationsand sleeping without shoulder pain. : average AROM (active range of motion) is quite complete(l60° forward flexion, l60° abduction, 40° external rotation, lntemal rotation to midback) as wellas strength restoration is quite good (Supraspinatus 4+/5, Infraspinatus 4/5, Negative ER lag sign,Subscapularis 5/5).The OrthADAPT® Bioimplant provided beneficial reinforcement of this chronic, massive retractedrotator cuff tear.
BIOCERAMICS IN SEVERE BONE LOSS DEFECT MANAGEMENT
IN REVISIONTOTAL KNEE ARTHROPLASTY
S. Zanasi, M. Pastina, F. Lenzi
Villa Erbosa Hospital, Gruppo San Donato, OrthopaedicsDept. Bologna, Italy
The alternatives available for management of bone defects in revision total knee arthroplastyinclude prosthetic augments, autograft, allograft, and the use of bone cement. The selection of theaugment technique should be based on the defect size, the patient age and life expectancy, and anassessment of the documented clinical results of each method. Prosthetic augments will address thevast majority of defects. The use of allograft is primarily indicated in the setting of major bone lossin revision knee arthroplasty: massive bone defects are challenging problems in revision kneesurgery and when defects are large and uncontained (without a cortical rim), structural allograftsmay be used to provide support for femoral and tibial components. The use of autograft isappropriate in the management of small defects in primary arthroplasty. Bone cement can be usedfor small defects if the stability of the implant is not compromised by the defect. A new tools,ENGIPORE and FINBLOCK a bioceramic bone substitutes in granules and blocks can find analtemative indication in management of all three types of femoral and tibial defects according toEngh classification. The benefit of the bioceramics consists of creating a perfect synergybetween the biochemical stimuli and the structural ones facilitating the neo-osteosintesis. The new generation hydrossiapatitis biomaterial, in contact with thephysiological fluid, create the ideal microenvironment to receive the necessarybiological stimuli for the bony development. The interconnected porosity plays adecisive role in the osheointegration process allowing a total communication betweenthe biomaterial and the surrounding environment favoring the bony formation. By developing an innovative process of production based on the nanotechnology, a biomaterial with acompletely similar architecture to that one of the natural bone has been come true. This particularstructure confers to the biomaterial a porosity that catches up 90%: it means that the new bone findsthe ideal space for its natural formation. The high porosity joined to the microstructuralmorphologic features give ENGlpore amazing ability to absorption of the physiological fluid.Thanks to this "sponge effect”, just it has been applied in situ, ENGIpore absorbs, for all itsthickness, those bioactive proteins and growth factors that render more effective and fast thecolonization and the differentiation of the cells deputies to bony regeneration. In this wayENGIpore in a short time acquires an increasing stability and mechanical resistance until completeintegration vdth new bone. We present main exemplificative applications of the bioceramic in thetreatment of different severe bone defect in revision total knee arthroplasty
HYALOGRAFT-C ACI VERSUS BIOSEED-C IMPLANTATION FOR CARTILAGEREPAIR AT 3 YS F.UP IN SPORTSMAN
S. Zanasi, M. Pastina,F. Lenzi
Villa Erbosa Hospital, Gruppo San Donato, OrthopaedicsDept. Bologna, Italy
Recent technologic improvements have aimed to overcome the intrinsic technical disadvantages ofACI by using cartilage tissue engineering grafts developed with three-dimensional scaffolds ormatrices that contain autologouschondrocytes for cartilage regeneration. Biomaterials that havebeen used include hyaluronan and collagen type I , and safety and effectiveness have beendemonstrated for cartilage repair. The aim of work was to analyze clinical effectiveness ofrepairing of focal articular cartilage defects using a modification of ACI based on autologouspolymer-based three-dimensional chondrocyte grafts.(BioSeed-C —a polyglycolic/polylactic acidand polydioxane based material), and culture-expanded autologouschondrocytes, suspended infibrin, that are seeded and dispersed within the matrix., versus Hyaluron-C as a stable, resorbable,three-dimensional matrix for tissue engineering, particularly for orthopedic application.We evaluated the cell-seeded, two-component, gel-polymer compositediyaluran acid in thearthrotomic and arthroscopic treatment of post-traumatic and degenerative cartilage defects in agroup of patients suffering from chronic post-traumatic or degenerative cartilage lesions of theknee. Clinical outcome was assessed in two omogenous group of 50 patients with a clinical followup at 3, 6, 12, and 24 months after implantation. Evaluations were based on the modified CincinnatiKnee Rating System, the Lysholm Score, the Knee Injury and Osteoarthritis Outcome Score, andthe current health assessment form of the International Knee Documentation Committee, as well ashistologic analysis of second-look biopsies. The findings reported demonstrate a number ofadvantages of this second-generation ACI Bioseed-C approach over the Hyalograft-C procedure.Specifically, by using a stable, three-dimensional matrix, seeded chondrocytes are retained moreefficiently at the site of implantation, which should promote integration between the neo-cartilageand the surrounding host articular cartilage tissue. A critical feature of the technology is the use of agel carrier for the seeded cells to perfuse into the three-dimensional polymer scaffold, a method thatessentially anchors the cells within the mechanically stable scaffold while providing an environment that has been shown to enhance the chondrocyte phenotype, In addition to favorable clinical scores,Ossendorf and coworkers also reported histologic results on second-look biopsies after implantationof the gel-polymer based chondrocyte graft BioSeed-C. The engineered graft showed mostlyhyaline cartilage with some fibrocartilage, and presence of viable chondrocytes and absence ofcalcification, apoptosis, necrosis, and formation of a fibrous repair tissue. However, there wasunevenness in the graft in terms of matrix staining, suggesting that the neo-cartilage may not behomogeneous, which could result in compromised mechanical properties. It is noteworthy that thehistologic analysis was derived from 18% of the patients who underwent second-look arthroscopy as a result of grinding, catching, pain, or swelling of the knee, a rate comparable to that in otherstudies reporting rates of revision surgery between 0% and 25% . Failure rate with the BioSeed-Cprocedure was only 2% (1/50), which is considerably lower than the 10% reported for 2nd-generation ACI Hyalograft-C. The significantly reduced operating time and the potential forarthroscopic application are additional benefits of the procedure reported here. In particular, theimprovement in graft fixation presents the possibility to repair defects that are larger than focallesions, which currently are the sole indication for ACI. Compared with the use of native matrixmaterials alone, such as collagen and hyaluronan, the cells are better retained in the mechanicallymore stable BioSeed-C procedure. Another advantage is that no cover material, such as theperiosteum used in the original ACI procedure, is required. It should be noted that in the studyconducted by Ossendorf and coworkers no specific selection of osteoarthritic patients wasconducted using the more standard International Cartilage Repair Society scoring system, and theclassification of osteoarthritis was done primarily based on radiographic observations. A moretargeted study in patients with defined osteoarthritis is clearly required to test the applicability ofthe BioSeed-C procedure for larger sized cartilage repair of osteoarthritic lesions. These findingssuggest that implantation of autologouschondrocyte-seeded BioSeed-C is an effective treatmentoption for the regeneration of post-traumatic or osteoarthritic defects of the knee.