Metaphyseal Defects Research Articles

Articular Cartilage Changes

The morphologic changes of articular cartilage with bone grafting to fill subchondral bone defects were studied in 23-month-old New Zealand rabbits with bilateral tibial subchondral bone defects. The defects were made approximately 5 mm below the articular surface and were covered with surrounding tissues. The right side was filled with calcium sulfate bone graft, and the left side was filled with acrylic cement as control. The articular cartilage above the fillers was harvested 12 weeks postoperatively. Gross observation, histological examination, and transmission electron microscope observation were undertaken. The results showed that cartilage above the calcium sulfate had a normal hyaline articular cartilage appearance. In contrast, cartilage above the acrylic cement showed degenerative changes in both histological and electron microscope observation. These results suggest that using calcium sulfate bone graft to fill subchondral metaphyseal bone defects has no harmful effect to overlying articular cartilage. This substitute can reduce the possibility of osteoarthritis compared to acrylic cement.

Porous Tantalum Cones for Large Metaphyseal Tibial Defects in Revision Total Knee Arthroplasty: A Minimum 2-Year Follow-up

Sixteen cases of revision total knee arthroplasty requiring the use of porous tantalum tibial cones for 2 T2A, 3 T2B, 4 T3A, and 7 T3B tibial bone defects (Anderson Orthopaedic Research Institute classification) after 13 cases of aseptic loosening and 3 cases of staged reimplantation for infection were reviewed. At an average 31 months (24-38), no patients were lost to follow-up. There were 2 cases of recurrent sepsis requiring removal of a well-fixed cone. In the remaining 14 cases, the reconstructions were functioning well with no reoperations. Radiographs demonstrated reestablishment of the joint line, neutral mechanical axis (average, 5.4° of valgus), and signs of stable osteointegration into the cones. Good short-term results were achieved in complex revisions, with these new reconstructive tools.

A comparison of RhBMP-7 (OP-1) and autogenous graft for metaphyseal defects after osteotomy of the distal radius

SUMMARY AIM: The aim of the study was to demonstrate whether RhBMP-7 is an effective alternative to autogenous bone graft in the healing of metaphyseal defects in the distal radius following corrective osteotomies for symptomatic malunion after distal radial fractures. Thirty patients were entered into the study and were randomised to receive either RhBMP-7 or autogenous bone graft harvested from the ipsilateral iliac crest. Stabilisation of the osteotomy was either carried out with non- bridging external fixation or the pi-plate. Clinical, radiographic and functional review were carried out at regular intervals up to 1 year. The first 10 patients were treated using non-bridging external fixation of the osteotomy. Two of the 4 patients treated with RhBMP-7 developed excessive osteolysis around the osteotomy site resulting in loss of the corrected position and non-union of the osteotomy. The other 2 patients healed at 13 weeks. The 6 patients treated with autogenous bone graft all healed at an average of 7 weeks, without any complications. It was postulated that the osteolysis was related to instability of the osteotomy site, and the use of external fixation was abandoned and replaced with internal fixation with a dorsal pi-plate. In the pi-plate group of patients, 10 were treated with autogenous bone graft and 10 with RhBMP-7. The bone graft patients healed at 7 weeks compared to 18 weeks for the RhBMP-7 patients, which was statistically significant (p = 0.019). The patients who received bone graft had complete filling of the metaphyseal defect radiologically. Five patients treated with RhBMP-7 healed at the volar cortex with a dorsal defect remaining at 1 year. Two patients developed non-union radiologically. Ten patients (3 in the RhBMP-7 and 7 in the bone graft groups) required plate removal for soft tissue complications. RhBMP-7 does not confer the same stability as bone graft, allowing shear forces across the osteotomy site when used in conjunction with non-bridging external fixation, reducing the capacity for healing and resulting in osteolysis. Using the RhBMP-7 with a pi-plate resulted in healing of the osteotomy, but at a slower rate than autogenous bone graft.

Ankle Fusion for Definitive Management of Non-Reconstructable Pilon Fractures

Highly comminuted pilon fractures, especially with a compromised soft tissue envelope, present a challenging treatment scenario. This study presents our results for patients managed with ankle fusion rather than ORIF. Fourteen patients with ankle joint incongruence after non-reconstructable tibia pilon fractures were treated with primary tibiotalar arthrodesis using a fixed-angle cannulated blade plate. Delayed metaphyseal unions due to bone defects were treated concurrently. The subtalar joint was preserved in all cases. Metaphyseal healing and stable arthrodesis was obtained in each case. There was one case of blade plate breakage in a patient who still achieved successful arthrodesis without reoperation. Union was achieved at an average of 15 weeks. No secondary procedures were required to obtain union. All 14 patients were ambulatory at last followup. Average followup was 39 weeks. Primary ankle arthrodesis can be achieved using a cannulated blade plate to address a non-reconstructable articular surface and metaphyseal bone defects in complex tibia pilon fractures.

A Representative Case of Osteoporotic Distal Radius Fracture

We present a case with nonsimultaneous bilateral dorsally displaced unstable osteoporotic distal radius fractures treated by open reduction and internal fixation using a volar and dorsal locking-plate system in a 69-year-old man. On the left side the patient had a loss of reduction as a result of plate bending 1 week after palmar plating. Correction of the dorsopalmar tilt was achieved through additional dorsal plating. Three months later the same patient sustained a distal radius fracture on his right forearm. Open anatomic reduction could only be achieved using palmar and dorsal locking plates, and the large metaphyseal defect was filled with resorbable bone substitute. Six weeks after surgery the patient reported persisting wrist pain. The x-rays showed loss of reduction. Because of flexor tendon irritation, the plate had to be removed after healing malunited. At the final follow-up at 18 months, the patient showed good subjective results according to the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire results. Active wrist motion was 60 degrees extension on the left and 55 degrees extension on the right. The active range of flexion was 50 degrees for left and right wrist, and active pronation and supination were unrestricted for both forearms. Grip strength was 50 kg on either side. Although recently good and excellent results have been reported treating distal radius fractures using volar locking plates in elderly individuals, we believe these implants still have their limits depending on local bone quality and fracture pattern. Decisionmaking for surgery versus conservative treatment should balance the risks and advantages for each patient accurately.

The efficacy of Biobon™ and Ostim™ within metaphyseal defects using the Göttinger Minipig

To compare bio, osteocompatibility, rate of resorption and remodeling dynamics of two clinically used bone substitutes. In a randomized fashion Biobon and Ostim were implanted bilaterally into the proximal metaphyseal tibiae of 18 Göttinger Minipigs in a direct right versus left "intra-individual" comparison. Fluorescent labelling was used. Microradiographic, histological and morphometric evaluation was carried out at 6, 12 and 52 weeks. Both bone substitutes showed good biocompatibility, bioactivity and osteoconductivity. The degradation dynamics of both materials differed. Degradation of Ostim stopped after 6 weeks postoperatively, whereas Biobon was degraded slowly but evenly over the time intervals. Only at 6 weeks a significant (P < 0.05) difference in resorption rate was detected. Both Biobon and Ostim showed incomplete resorption after a year. After 1 year no "restitutio ad integrum" could be observed in either group. Similar to ceramics, a thorough osseous incorporation seemed to inhibit further degradation of both bone substitute materials.

Knochenersatzmaterialien

Bone substitutes are used to supplement or substitute autogenous transplantation of cancellous bone. These materials should provide a scaffold structure and support bone healing alone or in combination with other substances. In trauma surgery the indication for use of bone substitutes lies mostly in filling of small metaphyseal cancellous bone defects with high vascularization following fracture. In comparison to transplantation of cancellous bone, the advantages of bone substitutes are sufficient availability without additional donor site morbidity. Moreover, biomaterials can be stored, also ensuring ready availability. This educational article gives an overview of bone substitutes currently in clinical use.

The use of freeze-dried cancelous allograft in the management of impacted tibial plateau fractures

The purpose of this study is to assess the behaviour of freeze-dried cancellous allograft used for supporting the reconstructed articular surface in impacted tibial plateau fractures. Freeze-dried cancellous allograft was used as metaphyseal defect filling agent in twenty-three patients (fifteen men and eight women, mean age 53 years), who suffered impacted tibial plateau fractures. According to Schatzker classification, ten fractures were classified as type II, six as type III, three as type V and four as type VI. All fractures were treated with open reduction-internal fixation after restoration of the tibial plateau surface and insertion of freeze-dried allograft chips for subchondral support. The mean follow-up was 13 months. The clinical and radiological outcome was assessed according to the modified Rasmussen system. The freeze-dried allograft incorporated soundly in all cases within 12 weeks from surgery and no complications that could relate to the graft were recorded. Freeze-dried allograft has specific advantages in comparison to autograft or other grafts and the results of the present study justify its use in the treatment of impacted tibial plateau fractures.

Observations on the microvasculature of bone defects filled with biodegradable nanoparticulate hydroxyapatite

The microvascularization of metaphyseal bone defects filled with nanoparticulate, biodegradable hydroxyapatite biomaterial with and without platelet factors enrichment was investigated in a minipig model. Results from morphological analysis and PECAM-1 immunohistochemistry showed the formation of new blood vessels into the bone defects by sprouting and intussusception of pre-existing ones. However, no significant differences were observed in the microvascularization of the different biomaterials applied (pure versus platelet factors-enriched hydroxyapatite), concerning the number of vessels and their morphological structure at day 20 after operation. The appearance of VEGFR-2 positive endothelial progenitor cells in the connective tissue between hydroxyapatite particles was also found to be independent from platelet factors enrichment of the hydroxyapatite bone substitute. In both groups formation of lymphatic vessels was detected with a podoplanin antibody. No differences were noted between HA/PLF− and HA/PLF+ implants with respect to the podoplanin expression level, the staining pattern or number of lymphatic vessels. In conclusion, the present study demonstrates different mechanisms of blood and lymphatic vessel formation in hydroxyapatite implants in minipigs.

Microparticulate Cortical Allograft: An Alternative to Autograft in the Treatment of Osseous Defects

Benign bone tumors are commonly diagnosed and treated. Following tumor removal, the defect in the bone can be filled with auto- or allografts, (degradable) bone substitutes or non-degradable polymethylmethacrylate. The ideal substitute for this purpose should provide immediate structural support and readily incorporate into bone over a short period of time. Experimentally, microparticulate allograft has been shown to incorporate quickly in metaphyseal and metadiaphyseal cortico-cancellous defects in primates [1]. Using a combination of small allogeneic cortical graft particles (< 250 µm), bone defects were filled following intralesional excision in 97 consecutive patients with benign and low grade malignant tumors and tumor-like conditions of bone. The clinical results and rate of radiographic incorporation and osseous consolidation were recorded and analyzed. These patients underwent 104 procedures in which osseous defects were packed with microparticulate allograft. The follow-up was from 23 to 49 months. There were 94 (90.3%) closed defects and 10 (9.7%) open defects. The average size of the grafted defect was 42.8 cm3 (0.48 - 315.0 cm3). Internal fixation was used in 11 of the 104 procedures (10.6 %). Radiographically, incorporation was observed in 91% of patients and consolidation in 60%. There were eleven failures (10.6 %), eight (72 %) due to tumor recurrence. Seven of eight patients with tumor recurrence underwent a second resection and grafting procedure that resulted in allograft incorporation and defect healing. There were two deep infections requiring debridement with retention of the graft; both resolved with satisfactory healing.Both incorporation and consolidation were observed in over 90% of patients with a low rate of complications. The use of small-particle cortical allograft proved to be an effective alternative to autogenous bone graft in patients with metaphyseal and metadiaphyseal surgical bone defects.

β-TCP bone graft substitutes in a bilateral rabbit tibial defect model

The use of artificial bone graft substitutes has increased as the surgical applications widen and the availability of allograft bone decreases. The ideal graft substitute should reabsorb with time to allow and encourage new bone formation whilst maintaining its properties as an osteoconductive scaffold until it is no longer required. A potential disadvantage of some synthetic substitutes is their long dissolution time. Beta-tricalcium phosphates ( β-TCPs) have some advantages when compared to hydroxyapatite (HA), when used as a filler, in that it is more rapidly reabsorbed. Three commercially available and clinically used β-TCP bone graft substitutes with the same chemistry (Vitoss, Osferion, Chronos) but with varying macro and microscopic characteristics were investigated using a bilateral tibial metaphyseal defect model in New Zealand white rabbits. When placed into tibial defects all three materials performed similarly in terms of mechanical properties of the healing defects. A decrease in properties was found at 12 weeks where implant resorption was nearly achieved while remodelling of the anteromedial cortex had yet to be completed. All materials were osteoconductive and supported new bone formation while implant resorption with time differed between materials. Vitoss resorbed faster than the other materials and is likely to differences in particle geometry, pore structure and interconnectivity.

Evaluation of a novel nanocrystalline hydroxyapatite paste and a solid hydroxyapatite ceramic for the treatment of critical size bone defects (CSD) in rabbits

The purpose of our study was to test the effectiveness of Ostim nanocrystalline hydroxyapatite paste and Cerabone ceramic by treating a critical size bone defect (CSD) on the right foreleg of a white New Zealand rabbit. Evaluation was carried out by comparing four groups each with a different CSD filling: an only OSTIM bone filling, an only Cerabone filling, an OSTIM-Cerabone combination, and a control group with no filling of the CSD. The results of this study display a rapid and uniform bone ingrowth following the CSD filling with Ostim. The histological and histomorphometrical data have shown similarly excellent results for both the Ostim and Cerabone-Ostim groups. The control group faired poorly in comparison, as three cases of non-union were observed and none of the defects were totally refilled with fresh bone within 60 days. The successful bone healing with osseous consolidation verifies the importance of the nanocrystalline hydroxyapatite in the treatment of metaphyseal osseous volume defects in the metaphyseal spongiosa.

Extended Curettage for Benign Bone Lesions

Benign bone lesions present a unique challenge to the practicing orthopaedist. They are a not uncommon problem that often present in the pediatric or young adult population. The most common diagnoses include giant cell tumor of bone, aneurysmal bone cysts, unicameral (simple) bone cysts, metaphyseal fibrous defects, and fibrous dysplasia. Appropriate surgical intervention must balance acceptable recurrence rates and surgical morbidity in line with their benign diagnosis. Historically, early surgical invention had unacceptably high recurrence rates. A more aggressive surgical approach to these lesions significantly decreased recurrence rates but surgical morbidity rose to levels considered unacceptable for benign lesions. Extended curettage offers a satisfactory compromise with decreased recurrence rates and significantly less surgical morbidity. Extended curettage is a technique of intralesional excision where the margins of the excision are extended by a surgical, chemical, or thermal adjuvant. Adjuvant options include phenol, liquid nitrogen, high-speed burr, cementation with polymethylmethacrylate, and argon-beam coagulation. The technique described here uses a combination of high-speed burr, argon-beam coagulation, and cementation to treat benign bone lesions resulting in an acceptable recurrence rate and acceptable rate of surgical morbidity.

The Risk for Fractures after Curettage and Cryosurgery Around the Knee

Curettage and cryosurgery have been used successfully for treatment of benign locally aggressive and some low-grade malignant bone tumors. After treating these lesions, we reconstruct residual bone defects around the knee with cement, intramedullary pins, and autogenous bone graft for subchondral augmentation and closure of cortical windows. We questioned the incidence of fractures and the rates of nonunion and malunion and asked whether patients at risk for fractures can be identified. We conducted chart and radio-graphic reviews of 60 consecutive patients who had curettage and cryosurgery of primary bone lesions in the distal femur or proximal tibia. Ten of the 60 patients (17%) sustained postoperative intraarticular fractures. Patients who sustained fractures had (1) more freeze-thaw cycles; (2) metaphyseal defect ratios greater than 0.6 and 0.8 on the anteroposterior and lateral projections, respectively; and (3) 4 mm or less proximity of the defect to the joint. Only one fracture united in good alignment. Radiographic measurements can assist in identifying patients at risk for fractures after curettage and cryosurgery around the knee. We expect the fracture rate to decline by reducing the number of freeze-thaw cycles and improving our reconstruction method.

Sagittaler Bewegungsumfang nach dorsalen radiokarpalen Luxationsfrakturen

Radiocarpal fracture dislocation is a rare, complex injury characterised by dislocation of the radiocarpal joint with avulsion of the dorsal or palmar cortical margin of the distal radius. To evaluate the sagittal motion at the radiocarpal and midcarpal levels following dorsal radiocarpal fracture dislocation (Moneim type I) nine cases were investigated clinically and radiologically. In a retrospective follow-up examination, eight patients could be included. The average follow-up was 4.1 years. One patient had a bilateral injury. The operative approach was bilateral in all cases. Restoration of the radial articular surface, filling metaphyseal defect zones with cancellous bone graft and internal fixation with a special T-plate were performed from dorsal. For refixation of the radiocarpal ligaments a small palmar approach was used. Standard anteroposterior and lateral radiographs, as well as lateral views in full extension and flexion were taken at follow-up. Clinical investigation included measurement of active range of motion, grip strength and pain evaluation using the VAS. Radiological evaluation of the standard lateral view turned out a mean angle between scaphoid and lunatum of 55.6 degrees, capitatum and lunatum of -11.6 degrees and radius and capitatum of 10.5 degrees. In full flexion the following angles were measured: radius/lunatum 15.3 degrees, capitatum/lunatum 18 degrees and between radius and capitatum 30 degrees. In full extension the angles averaged: radius/lunatum -23.9 degrees, capitatum/lunatum -31 degrees and between radius and capitatum -55 degrees. According to the Knirk and Jupiter classification system, five patients presented arthritis stage 1, three arthritis stage 2 and one a stage 3 arthritis. Clinical evaluation showed a mean wrist motion of 55 degrees for extension, 35 degrees for flexion, 88 degrees for pronation, 70 degrees for supination and 25.5 degrees for the mean radial as well as the mean ulnar motion. The average Mayo Wrist Score was 76.1 points. Operative treatment of dorsal radiocarpal fracture dislocation using a bilateral approach led to satisfying results in eight of nine cases with decreased but radiologically evaluated sagittal motion of the proximal row.

Grenzen der palmaren winkelstabilen Plattenosteosynthese bei instabilen distalen Radiusfrakturen

The use of locking plate systems in the treatment of distal radius fractures has increased during the last years. In the presented study our experience and results after palmar plating of dorsal dislocated distal radius fractures are analysed and presented. Besides the functional and radiological results, the potential surgical risks and the observed complications are discussed. Over a mean 15-month period, 112 consecutive patients (24 men, 88 women) with an average age of 57 years who were treated for an unstable dorsal dislocated distal radius fracture using the palmar locking-plate system could be assessed. The functional results were compared with the uninjured contralateral side. The subjective pain level was assessed using the visual analogue scale (VAS) and the subjective results were assessed using the Disabilities of the Arm, Shoulder, and Hand (DASH) Score. Radiographic assessment included palmar tilt, radial inclination, and ulnar variance. The objective and subjective functional results were evaluated using the modified Mayo-Wrist Score. Functional results: extension slashed circle 53.1 degrees (84 % as compared with the uninjured side); flexion slashed circle 45.8 degrees (81 % as compared with the uninjured side); pronation slashed circle 78.7 degrees (95 % as compared with the uninjured side); supination 81.9 degrees (95 % as compared with the uninjured side); grip strength slashed circle 56 Kp (73 % as compared with the uninjured side). Radiological results: postoperative reduction/mean postoperative loss of reduction: radial inclination: slashed circle 20.4 degrees /slashed circle 0.2 degrees ; palmar tilt: slashed circle 0.2 degrees /slashed circle 3.1 degrees ; ulnar variance: 0.08 mm/slashed circle 0.42 mm. Pain values: slashed circle 2.7 points; DASH score: slashed circle 14.8 points; complications: breakage of plates 1 %, screw loosening 3 %, intraarticular screw position 2 %, delayed bone union 4 %, rupture M. extensor pollicis longus 2 %/M. flexor pollicis longus 3 %, peritendinitis extensor tendons 5 %, synovialitis flexor tendons 8 %, CTS 3 %, complex regional pain syndrome 6 %. Favourable indications for palmar locking plate osteosynthesis are A2, A3, C1 and C2 fractures with big distal fracture fragments. In these cases, additional bone grafting is not needed. In very distal fractures, multidirectional plate-systems are advantageous. Multifragmental C3 fractures show a high complication rate. Additional bone grafting for the metaphyseal defect should be considered.

The Biocompatibility of Biodegradable Glycine Containing Polyphosphazenes: A Comparative study in Bone

Polyphosphazenes have gained considerable attention as biomaterials for use in tissue engineering and orthopaedic reconstruction. In this paper we examined the polyphosphazenes’ in vivo biocompatibility and degradation by studying their ability to repair bone in a rabbit metaphyseal distal femur defect model. Matrices constructed from poly[(50% p-methylphenoxy)-(50%ethyl glycinato) phosphazene] (PPHOS-50) and poly[bis(ethyl glycinato) phosphazene] (PPHOS-100), were surgically implanted into a metaphyseal rabbit defect of the distal femur as constructs for tissue regeneration. Poly(lactide-co-glycolide) (PLAGA) implants, which are the biodegradable polymers most widely used clinically, and defects without polymers were used as controls in this experiment. Histological studies demonstrated that both PPHOS-50 and PPHOS-100 appeared to support bone growth comparable to the control PLAGA. By 12 weeks, femurs with polyphosphazene implants showed evidence of bone in-growth and a mild fibrous response. The PPHOS-50 implants were found to have a local tissue response that was more favorable than PPHOS-100 and similar to PLAGA. Biodegradable polyphosphazenes are a novel class of polymers which have been observed to facilitate bone growth in vivo.

Effects of platelet factors on biodegradation and osteogenesis in metaphyseal defects filled with nanoparticular hydroxyapatite—an experimental study in minipigs

There are no studies on the cellular activity in the early phase of biodegradation and bone healing of bone substitutes loaded with platelet factors (PLF). The purpose of this study was to evaluate the cellular effects of PLF in combination with nanoparticulate hydroxyapatite (HA) on the biodegradation and bone formation after 20 days. Autogenous PLFs were obtained by centrifugation of miniature pig blood samples and subsequent degranulation of platelets by calcium and thrombin. A cylindrical bone defect with a diameter of 8.9 mm was created in the distal femoral condyle of 20 miniature pigs. Four of the defects were left empty, 8 were filled with HA with loading and 8 with HA loaded with PLF. The distal femur was harvested after 20 days and TRAP-staining, cathepsin-K and CD44 staining and scanning electron microscopy were performed for cellular assessment of biodegradation was done. Histomorphometry of new bone formation and of biodegradation of HA material was performed. PLF loading of HA led to statistically significant more TRAP-positive cells with enhanced biodegradation of the nanoparticulate HA but no statistically enhanced new bone formation compared to unloaded HA. Furthermore, there was a higher number of CD44 and cathepsin-K positive cells by PLF-loading. In summary, PLF led to stimulation of the cellular process of the biodegradation of HA.

Management of Bone Loss in Revision Total Knee Arthroplasty

Bone deficiencies around the knee can present a substantial challenge during revision total knee arthroplasty. Bone loss occurs from stress shielding, osteolysis, chronic infection, and bone removed during implant extraction. Smaller defects have traditionally been treated with cement filling or allograft bone chips. Larger defects can be reconstructed with bulk allografts or custom prostheses. A hinged prosthesis may be necessary to account for ligamentous insufficiency. In addition to traditional methods of managing bone loss, recent developments include the use of metaphyseal-filling implants made of highly porous metal. These implants can be press-fit into host bone to accommodate large metaphyseal defects. Each revision knee surgery provides unique challenges, requiring proficiency in multiple techniques of bone loss management.

Outcome of raft plate fixation of split depressed tibial plateau fracture without using a bone graft

Schatzcker type 3 tibial plateau fractures are common intra-articular injuries. These fractures can be associated with significant depression of articular surface, usually requiring open reduction, elevation of articular surface and rigid internal fixation. The resultant metaphyseal defect is filled with either cancellous autografts (Lachiewicz in Clin Orthop Relat Res 259:210–215, 1990) allografts or calcium phosphates to maintain the reduction. Percutaneous fixation (Koval in J Orthop Trauma 6:340–346, 1992) and ring fixators have been used to stabilize these fractures. Autogenous bone-graft harvesting is associated with significant morbidity with reported major complication rate of 8.6% and minor complication rate of 20.6% and there is a limited availability for larger defects. Allografts and bone substitutes are associated with their own problems (Segur in Arch Orthop Trauma Surg 117(6,7):357–359, 1998). The purpose of this study was to review the outcome of split depressed tibial plateau fractures treated by open reduction and internal fixation using subchondral raft plate fixation without the use of bone graft.