High complication rate in the early experience of minimally invasive total hip arthroplasty by the direct anterior approach

Background and purpose?Poor bone ingrowth into the porous coating of tibial components has been reported. We hypothesized that iliac marrow grafting might be useful to enhance bone ingrowth into a porous-coated implant. The first part of this study was to examine the presence of fibroblast colony-forming units (CFUF) containing osteogenic precursor cells in tibial bone marrow and iliac bone marrow. The second aim was to compare the clinical and radiographic results after bilateral total knee arthroplasty (TKA) with and without autologous bone marrow transplantation to the bone-implant interface.

Methods?Simultaneous bilateral TKA was performed in 21 patients with osteoarthritis. Aspirated iliac bone marrow was transplanted to the interface of one randomly selected porous-coated tibial component in each patient, and contralateral knees served as controls. All of the 21 patients were followed for 5 years.

Results?The average number of CFU-F was significantly lower in tibial marrow than in iliac marrow (p = 0.008). The final fluoroscopically-guided radiographs revealed a decrease in the number of knees with radiolucent lines after marrow grafting compared to those without grafting (p = 0.004).

Interpretation?Iliac bone marrow is useful as a bone grafting material to enhance the biological fixation in porous-coated implants.     

Outcome of isolated tibial polyethylene insert exchange after uncemented total knee arthroplasty: 27 patients followed for 8-71 months

Background The outcome of performing isolated tibial polyethylene insert exchange (ITPIE) after total knee arthroplasty (TKA) is under debate. We evaluated the survival probability of ITPE after uncemented TKA.

Method 27 patients (27 knees) with an ITPIE performed mean 9 (0.9-17) years after the initial TKA were included in the study (22 patients also had the patellar component replaced simultaneously). All patients had their exchange performed at our department between 1997 and 2001 and had their latest follow-up examination mean 40 (8-71) months after the exchange.

Results During the follow-up, 2 patients had total knee revision because of aseptic loosening and 2 patients had isolated patella component exchange (in 1 of the patients, combined with a new ITPIE). Kaplan-Meier survival analysis gave a survival probability of 80% at 34 months of follow-up.

Interpretation The short-term survival after an ITPIE was similar to that of a total knee revision with exchange of all components. Since the ITPIE is a much smaller operation with fast rehabilitation, we recommend it in elderly patients with a well-fixed and wellaligned prosthesis without surface damage of the components.     

No positive effects of OP-1 device on the incorporation of impacted graft materials after 8 weeks: a bone chamber study in goats

Background Bone morphogenetic proteins (BMPs) have the potential to improve clinical outcome after hip revision surgery by improving graft incorporation and implant fixation. However, impaction of cancellous bone grafts and TCP/HA bone substitute mixed with OP-1 device in a bone chamber in goats in a previous study led to reduced fibrous tissue ingrowth after 4 weeks. New bone formation was not promoted by OP-1. In the current study we examined whether this reduction represented a final loss of ingrowth or was just a delay, and whether the reduction can be overcome and ultimately results in a better late ingrowth.

Methods Bone chambers with impacted allografts and impacted TCP/HA granules mixed with 2 doses of OP-1 device were implanted in proximal medial goat tibias. Impacted allografts and TCP/HA not treated with OP-1 served as controls. After 8 weeks, the incorporation was evaluated using histology and histomorphometry.

Results Histology revealed evidence of bone graft incorporation, which proceeded in a similar way in both allografts and TCP/HA, with and without the addition of OP-1. After 8 weeks, no difference in bone ingrowth was found between the OP-1 groups and their controls. It was only in the allografts that the addition of OP-1 resulted in more fibrous tissue ingrowth.

Interpretation We conclude that the previously observed delay in fibrous tissue ingrowth can be only partially overcome.     

Insufficient recovery of neuromuscular activity around the knee after experimental anterior cruciate ligament reconstruction

Background Operative and nonoperative treatment of anterior cruciate ligament (ACL) injuries is often associated with a lack of proprioception and persistent muscle weakness of unknown origin.

Methods This long-term study in the cat experimentally compares both neural and muscular activity in the articular nerves of the knee (PAN and MAN), quadriceps and hamstrings, in the chronic unstable knee, and in the reconstructed knee. We also investigated changes in neuromuscular response due to the mechanical competence of the graft, comparing stable and unstable reconstructed knees.

Results We found increased periarticular muscle activity during anterior tibial translation in chronically unstable knees. Both reconstructed and non-reconstructed knees lost fast reactive activity in the articular nerves. When stability was recovered after reconstruction, the knees showed a more adjusted—although incomplete—muscular reaction.

Interpretation ACL-injured knees in the cat, with or without reconstruction, show definite abnormalities in neuromuscular reaction in the long term. Regaining stability with a competent graft in the reconstructed knee is crucial for reduction of this anomalous reaction.     

Trochleaplasty for patellar instability due to trochlear dysplasia: A minimum 2-year clinical and radiological follow-up of 19 knees

Background Recurrent patellar dislocation may be associated with trochlear dysplasia. Trochleaplasty is a surgical procedure which strives to deepen the trochlear groove. We evaluated the clinical and radiological effect of trochleaplasty after a minimum follow-up of 2 years.

Patients and methods We examined 19 knees in 16 patients at a mean of 3 years after trochleaplasty. Postoperatively, a subjective questionnaire, a Kujala score, and tests for potential patellar redislocation and apprehension were evaluated. On radiographs we evaluated the preoperative and postoperative crossing sign, trochlear depth, trochlear bump, and patellar height. On CT scans, the pre- and postoperative tibial tuberosity to trochlear groove distance (TTTG) and the patellar inclination angle were measured.

Results 16 of 19 knees improved subjectively. The Kujala score increased from 56 to 80 points at the latest follow-up. None of the patients sustained a redislocation. 5 patients had medial parapatellar tenderness, including 4 with persistent apprehension. Radiological signs of trochlear dysplasia were corrected.

Interpretation Patellofemoral instability with underlying trochlear dysplasia can be treated successfully by trochleaplasty.     

Irradiation has no effect on the incorporation of impacted morselized bone: a bone chamber study in goats

Background Gamma irradiation has been widely used for sterilization of bone allografts. However, gamma irradiation alters proteins. This is favorable when it reduces immunogenicity, but is undesirable when osteoinductive proteins are damaged. Although the effect of gamma irradiation on BMPs has been studied, the effect of irradiation on the process of incorporation of morselized bone chips remains unclear. We studied the effects of sterilization by gamma irradiation on the incorporation of impacted morselized allografts.

Methods Bone chambers with impacted allografts, rinsed impacted allografts, allografts that were rinsed and subsequently irradiated, and an empty control were implanted in proximal medial tibiae of goats. Incorporation was evaluated using histology and histomorphometry.

Results Histology revealed evidence of bone graft incorporation, which proceeded in a similar way in unprocessed, rinsed, and both rinsed and irradiated bone grafts. After 12 weeks, no difference in bone and tissue ingrowth was found between the unprocessed, the rinsed, and the rinsed and subsequently irradiated allografts. The amount of unresorbed graft remnant was highest in the unprocessed bone grafts.

Interpretation We conclude that sterilization with gamma irradiation does not influence the incorporation of impacted rinsed bone allografts.     

Knee arthrodesis with the Sheffield external ring fixator: fusion in 6 of 10 consecutive patients

Background Knee arthrodesis with external fixation (XF) is a possible salvage procedure for infected total knee arthroplasties (TKA). We report the outcome in 10 patients who underwent arthrodesis with the Sheffield Ring Fixator.

Patients and methods The patients had primary arthrosis in 8 cases; 2 cases were due to rheumatoid arthritis and sclerodermia. The mean time between the primary TKA and arthrodesis was 6 (0.5-14) years. The average age at arthrodesis was 69 years. The average follow-up period was 10 months.

Results Stable fusion was obtained in 6 patients after a mean XF time of 3.6 (2-4) months. 1 patient was referred to another hospital because of nonunion. This patient showed fusion with intramedullary nailing after 7 months. 3 nonunion patients required permanent bracing. 7 patients had pin tract infections. Infections healed in all patients.

Interpretation The Sheffield Ring Fixator gives an acceptable fusion rate for arthrodesis in the infected TKA, with limited complications.     

Platelet-rich plasma accelerated surgical angio-genesis in vascular-implanted necrotic bone: an experimental study in rabbits

Background Platelets contain many kinds of growth factors with the ability to accelerate angiogenesis. We analyzed whether a single injection of platelet-rich plasma (PRP) would accelerate surgical angiogenesis in necrotic bone implanted with vascular tissue.

Methods We used 24 Japanese White rabbits. PRP was refined from autologous blood by separation twice with centrifugation. A removed iliac bone was frozen in liquid nitrogen to ensure complete cellular necrosis. A narrow hole was made in the bone and the saphenous vascular bundle was passed through the hole. The bone was wrapped after injection of either 1 mL (1) PRP, or (2) saline solution into the hole, and was placed subcu-taneously in the thigh. In both groups, angiogenesis was compared 1 week and 2 weeks after surgery.

Result Angiogenesis was observed along the implanted vascular bundle in both groups. At 1 and 2 weeks after surgery, both the vessel density and the average length of newly formed vessels of the experimental group were significantly greater than in the control group. Both the vessel density and the length were greater after 2 weeks than after 1 week.

Interpretation A single injection of PRP accelerates surgical angiogenesis in vascular-implanted necrotic bone.     

Systemic zoledronate precoating of a bone graft reduces bone resorption during remodeling

Background Cartilage degeneration often occurs after osteosynthesis of a devascularized intermediary fragment in a joint fracture, in mosaicplasty or in whole-joint toe-to-finger transplantation. Hypothetically, the degeneration is secondary to a collapse of the transferred subchondral bone as it remodels during high mechanical load. Bisphosphonates are used to reduce resorption of necrotic bone. We tested a systemic pretreatment before harvesting the graft in order to protect the bone and cartilage against collapse and secondary arthrosis.

Methods Rats were given one zoledronate injection and bone grafts were harvested. The grafts were frozen, thawed and placed into bone chambers, and implanted into another batch of rats. Graft resorption and new bone formation was measured by histomorphometric analysis and compared with untreated grafts.

Results In the remodeled area of the controls, the graft was almost totally resorbed and replaced by bone marrow. In the zoledronate-treated specimens, the graft remained and the graft trabeculas were lined with new bone. By histomorphometry, the total amount of bone (graft plus new bone) within the remodeled area was 16% in the zoledronate-treated grafts and 5% in the controls (p = 0.003).

Interpretation A bone graft can be pretreated with bisphosphonate and remain protected against resorption once implanted again. ▪     

Tibial intramedullary nails -- should they be removed? A retrospective study of 71 patients

Background Anterior knee pain and young age of the patient have been considered justification for removal of a tibial intramedullary nail. There have been few reports on the outcome after nail removal, however.

Patients and methods We studied 71 patients in whom 72 tibial nails had been removed. We used self-assess-ment questionnaires to evaluate the location, intensity, and frequency of pain before and after removal. The degree of satisfaction was scored on a visual analog scale.

Results 39 of 71 patients had less pain after removal of the nail, but were not asymptomatic. 14 patients had unaltered pain, and 18 patients had increased pain. 4 of 6 patients who had been treated with fasciotomy were not satisfied with the outcome of nail removal.

Interpretation The results of nail removal to alleviate pain are poor. Removal of a nail should not be undertaken unless there is a convincing indication.     

Mice expressing a constitutively active PTH/PTHrP receptor in osteoblasts show reduced callus size but normal callus morphology during fracture healing

Background The parathyroid hormone-/parathyroid hormone-related protein (PTH/PTHrP) receptor plays a crucial role in endochondral bone formation and possibly also in fracture healing. Patients with Jansen's metaphysial chondrodysplasia (JMC) have a gain-of-function mutation in the PTH/PTHrP receptor. Transgenic mice expressing JMC PTH/PTHrP receptor mutants in osteoblasts are characterized by increased trabecular bone formation and reduced osteoblastic activity at periosteal sites. We have analyzed the bone phenotype and studied the fracture healing process in this model.

Methods We performed bone density analysis of tibiae from 17-week-old transgenic mice and controls. Also, tibial fractures were produced in 14-week-old mice. Fracture healing was examined by radiographic and histological analysis.

Results Transgenic mice had a lower total bone mineral content (BMC), by a factor of one-third. The changes were bone compartment-specific with an increase in trabecular bone volume and a decrease in cortical thickness. The calluses in the transgenic mice were smaller, with a reduction in BMC and mean crosssectional area by a factor of one-half. Despite the smaller size, however, the morphology and progression through the healing process were similar in both transgenic and wild-type littermates.

Interpretation We conclude that the constitutively active PTH/PTHrP receptor has compartment-specific effects on bone formation when expressed in osteoblasts. During fracture healing, however, both the periosteal and the endochondral processes are activated, leading to fracture healing that is temporally and morphologically normal, although the callus tissue is less prominent.     

Forearm bone-anchored amputation prosthesis: a case study on the osseointegration

Background and purpose Bone-anchored titanium implants have been used for anchorage of amputation prostheses for more than one and a half decades. Histo-logical and ultrastructural analyses were performed on a forearm amputation prosthesis after being in use for more than 11 years.

Material, methods and results The implant was retrieved from the ulnar bone after a fatigue fracture of the titanium implant, and was clinically stable at the time of removal. The histological findings showed a large amount of bone within the threads and a high degree of apposition of mineralized bone to the implant surface. Ultrastructural analysis of thin samples prepared by focused ion-beam microscopy revealed an electron-dense layer at the interface and direct apposition of crystalline hydroxyapatite at the implant surface.

Interpretation Our observations in this retrieval study provide a structural correlate to the functional properties and clinical results of amputation prostheses.     

Implantation of perichondrium-derived chondrocytes in physeal defects of rabbit tibiae

Background Various cells and scaffolds have been used experimentally as interposition materials after physeal bar resection to treat partial physeal growth arrest. However, results of these cell therapies are unpredictable.

Methods We investigated the chondrogenic differentiation of rabbit perichondrial cells in vitro. We also investigated radiographic and histological changes after implantation of the perichondrium-derived chondrocytes, embedded in fibrin beads, into defects created in the medial aspect of the proximal tibial physis of 26 8-week-old New Zealand White rabbits. Physeal defects of the contralateral tibiae were left intact without any treatment, or were treated with fibrin beads not containing cells.

Results The perichondrial cells cultured in the alginate- fibrin beads were positive in immunohistochemical staining for S-100 protein and the extracellular area was stained with Safranin-O. RNase protection assay showed that the expression of type II collagen and aggrecan continued In the cell and bead-treated tibiae, varus deformity was reduced significantly and tibial length was maintained longer than that of the contralateral tibia. Histologically, cartilage clusters of varying size with intervening micro-bony trabeculae were found in the cell and bead-treated tibiae. The lateral, remaining physis in the untreated tibiae showed altered histology.

Interpretation Implantation of fibrin beads containing perichondrium-derived chondrocytes into the physeal defect helps to prevent angular deformation and shortening of long bone, but not completely. Physeal bony bar formation adversely affects the growth of the remaining physis from early stages onward.     

An economic analysis of management strategies for closed and open grade I tibial shaft fractures

Background Closed and open grade I (low-energy) tibial shaft fractures are a common and costly event, and the optimal management for such injuries remains uncertain.

Methods We explored costs associated with treatment of low-energy tibial fractures with either casting, casting with therapeutic ultrasound, or intramedullary nailing (with and without reaming) by use of a decision tree.

Results From a governmental perspective, the mean associated costs were USD 3,400 for operative management by reamed intramedullary nailing, USD 5,000 for operative management by non-reamed intramedullary nailing, USD 5,000 for casting, and USD 5,300 for casting with therapeutic ultrasound. With respect to the financial burden to society, the mean associated costs were USD 12,500 for reamed intramedullary nailing, USD 13,300 for casting with therapeutic ultrasound, USD 15,600 for operative management by non-reamed intramedullary nailing, and USD 17,300 for casting alone.

Interpretation Our analysis suggests that, from an economic standpoint, reamed intramedullary nailing is the treatment of choice for closed and open grade I tibial shaft fractures. Considering financial burden to society, there is preliminary evidence that treatment of low-energy tibial fractures with therapeutic ultrasound and casting may also be an economically sound intervention.     

The fascial band from semitendinosus to gastrocnemius: the critical point of hamstring harvesting: an anatomical study of 23 cadavers

Background Arthroscopically-assisted reconstruction of the anterior cruciate ligament with hamstring tendons has achieved widespread acceptance; however, the anatomy of these tendons may cause technical problems at harvesting.

Methods We studied the anatomy of the fascial band between semitendinosus and gastrocnemius and the distance between the semitendinosus insertion and the origin of this band in 23 knees from cadavers (17 male). The length of the semitendinosus tendon and the width of the fascial band were also recorded.

Results Fascial attachment was detected in all cadavers except 1. The mean width of the band was 2.6 (1-4) cm. The mean distance from the insertion of the semitendinosus to the fascial band was 7 (6-8) cm. The mean length of the semitendinosus tendon was 22 (18-26) cm.

Interpretation A better understanding of the anatomy of the hamstring tendons will reduce the risk of a disappointing complication right at the start of the operation.     

Low relapse with oral antibiotics and two-stage exchange for late arthroplasty infections in 40 patients after 2-9 years

Background and purpose Exchange surgery in late arthroplasty infection is directed against bacteria adhering to implants. Therapies based on antibiotics that are effective intracellularly have been proposed recently. We have combined both strategies to improve the cure rate.

Methods 40 consecutive patients (16 hips, 24 knees) were diagnosed with late arthroplasty infection. The organisms isolated were 35 Staphylococcus, 19 of which were methicillin-resistant, 4 Enterococcus, 6 Gram-neg-ative bacilli, and 4 Corynebacterium. The infections were managed by a combined therapy consisting of two-stage exchange surgery and two oral intracellularly-effective antibiotics. The antibiotics were selected according to bacterial sensitivity and intracellular and biofilm effectiveness. Second re-implantation surgery was delayed until clinical and analytical normalization. Patients were in hospital for only 1 week after each surgery, and were followed up prospectively on an outpatient basis (2-9 years). Cure of the infection was defined as absence of clinical, serological, and radiographic signs of infection during the whole follow-up.

Results The infection was resolved in 38/40 patients (15/16 hips and 23/24 knees).

Interpretation Oral antibiotics that are effective intracellularly in combination with two-stage exchange surgery is a promising alternative for treating late arthroplasty infections. Oral antibiotics shorten hospitalization and reduce patient discomfort.     

Influence of water and fat content on compressive stiffness properties of impacted morsellized bone: an experimental ex vivo study on bone pellets

Background The initial stability of an exchanged hip arthroplasty is crucial for the survival of the revised joint. Several factors can affect the outcome. The amount of liquid in morsellized bone has a major influence on the constrained stiffness properties of impacted bone applied in revision joint surgery.

Method To determine whether water or fat is the main contributing liquid, we performed an experimental study on impacted morsellized cortico-cancellous bovine bone to compare the constrained e-moduli in native bone and bone with modified water and fat content. The bone was impacted into bone pellets by a standardized method by which the construction procedure was monitored. Other stiffness properties were recorded during subsequent load testing.

Results Low water content significantly increased the constrained stiffness moduli during load, while high water content significantly reduced it. Low fat content increased stiffness significantly only during the initial phase of loading.

Interpretation Our findings indicate that the preparation and usage of morsellized bone in revision joint surgery should be performed under dry conditions to improve the initial stability of the revised prosthesis. ▪     

Tartrate-resistant acid phosphatase 5b (TRAP 5b) as a marker of osteoclast activity in the early phase after cementless total hip replacement

Background After total hip replacement, increased bone metabolism is seen. A local periprosthetic osteopenia can be measured by dual-energy X-ray absorptiometry (DXA), but it is still unkown whether biochemical markers can be used to monitor the local remodeling at an earlier stage.

Patients and methods In this prospective study we compared the biochemical markers tartrate-resistant acid phosphatase 5b (TRAP 5b), bone ALP, osteocalcin and CrossLaps with periprosthetic DXA in 17 consecutive patients after uncemented total hip replacement.

Results We found a highly significant early increase in TRAP 5b after 2 weeks and 6 weeks, which was followed by a densitometrically detectable decrease in bone mineral density after 26 weeks, especially in periprosthetic section Gruen zone 7. Bone ALP and osteocalcin levels as markers of osteoblast activity, and also Cross-Laps as a further marker of osteoclast activity, did not appear to allow any significant prediction of local bone remodeling.

Discussion Our findings show that TRAP 5b is a sensitive parameter for monitoring of osteoclast activity after cementless total hip replacement, and may predict local osteopenia.     

Serum total acid phosphatase for monitoring the clinical course of giant cell tumors of bone--26 patients with 5 local recurrences

Background Giant cell tumor of bone (GCT) is a bone-destroying tumor that sometimes recurs locally after treatment. A recent study showed increased levels of serum total acid phosphatase (TACP).

Methods We assessed TACP in the serum of 26 patients with primary GCT, and in 5 of them who developed a local recurrence.

Results We found a correlation between TACP level in serum and tumor size. TACP levels that were elevated preoperatively in patients with GCT became normalized after surgery, but increased in 3 of the 5 patients with local recurrence.

Interpretation TACP could be used as a tumor marker for monitoring response to treatment of GCT.     

The effect of recombinant human bone morphogenetic protein-2 on the osteogenic potential of rat mesenchymal stem cells after several passages

Background Since the osteogenic potential of bone marrow derived mesenchymal stem cells (BMSCs) becomes reduced with passage, establishment of culture condition that permit the rapid expansion of BMSCs while retaining their potential for differentiation is needed for clinical application. Bone morphogenetic proteins stimulate osteogenic differentiation in mesenchymal progenitor cells as well as increase stem cell numbers. Thus, we analyzed the effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) on the osteogenic potential of rat BMSCs over several passages.

Material and methods Osteogenic differentiation in vitro was evaluated in terms of the alkaline phosphatase (ALP) activity and the osteocalcin (OC) concentration in the supernatants, and the expression of ALP and OC mRNA in the cultured cells. For in-vivo osteogenesis, BMSCs cultured with and without rhBMP-2 through all passages were implanted into athymic mice.

Results  The levels of osteogenic markers were significantly higher in the cells of the BMP(+) group than in the cells of the BMP(-) group, although they decreased with passage irrespective of whether or not rhBMP-2 was added. Similar to the in-vitro experiments, there was a greater degree of bone and cartilage tissue formation in the BMP(+) group over all passages.

Interpretation  From our results, osteogenic potential can be maintained even in BMSCs that have been passaged several times in the presence of rhBMP-2. These cells are capable of inducing and participating in bone formation and can be used for clinical applications.