Osseointegrated Percutaneous Prosthetic System for the Treatment of Patients With Transfemoral Amputation: A Prospective Five-year Follow-up of Patient-reported Outcomes and Complications.

INTRODUCTION: Direct skeletal attachment of prostheses has previously been shown to improve patient-reported outcome (PRO) measures of individuals with transfemoral amputation (TFA) at 2-year follow-up. This prospective study reports the outcomes at 5-year follow-up. METHODS: A total of 51 patients (55 legs) with TFA were included in a prospective study. Complications, success rate, and PRO measures were followed for 5 years. RESULTS: The cumulative fixture survival rate at 5 years was 92%, and the revision-free survival rate was 45%. Thirty-four patients had 70 superficial infections. Eleven patients had 14 deep infections. Fifteen patients had mechanical complications. Four fixtures were removed (ie, one deep infection and three loosening). PRO measures showed significant improvements including more use of the prosthesis, better mobility, fewer issues, and improved physical health-related quality of life (all P < 0.0001) compared with baseline. CONCLUSION: Individuals with TFA at 5-year follow-up had significant improvement in PRO measures, but increases in deep infections and mechanical complications are concerning.

Increase of sodium channels (nav 1.8 and nav 1.9) in rat dorsal root ganglion neurons exposed to autologous nucleus pulposus.

PURPOSE: It has been assumed that nucleus pulposus-induced activation of the dorsal root ganglion (DRG) may be related to an activation of sodium channels in the DRG neurons. In this study we assessed the expression of Nav 1.8 and Nav 1.9 following disc puncture. METHOD: Thirty female Sprague-Dawley rats were used. The L4/L5 disc was punctured by a needle (n=12) and compared to a sham group without disc puncture (n=12) and a naive group (n=6). At day 1 and 7, sections of the left L4 DRG were immunostained with anti-Nav 1.8 and Nav 1.9 antibodies. RESULT: At day 1 after surgery, both Nav 1.8-IR neurons and Nav 1.9-IR neurons were significantly increased in the disc puncture group compared to the sham and naive groups (p<0.05), but not at day 7. CONCLUSION: The findings in the present study demonstrate a neuronal mechanism that may be of importance in the pathophysiology of sciatic pain in disc herniation.

Vibrotactile evaluation: osseointegrated versus socket-suspended transfemoral prostheses.

This study investigated detection thresholds of vibrometric stimuli in patients with transfemoral amputation supplied with osseointegrated (OI) and socket-suspended prostheses. It included 17 patients tested preoperatively with socket-suspended prostheses and after 2 yr with OI prostheses and a control group (n = 17) using socket-suspended prostheses, evaluated once. Assessments on the prosthetic and intact feet were conducted at six frequencies (8, 16, 32, 64, 125, and 250 Hz). Furthermore, measurements were conducted to investigate how vibrometric signals are transmitted through a test prosthesis. The results showed that the OI group had improved ability to detect vibrations through the prosthesis at 125 Hz (p = 0.01) at follow-up compared with the preoperative measurement. Compared with the control group, the OI group at follow-up had better ability to detect high frequency vibrations through the prosthesis (125 Hz, p = 0.02; 250 Hz, p = 0.03). The vibrometric signal transmitted through the test prosthesis was reduced at 8, 125, and 250 Hz but was amplified at 16, 32, and 64 Hz. Differences between the OI and the control groups were found in the highest frequencies in which the test prosthesis showed reduction of the vibrometric signal. The study provides insight into the mechanisms of vibration transmission between the exterior and bone-anchored as well as socket-suspended amputation prostheses.

Local application of nucleus pulposus induces expression OF P2X3 in rat dorsal root ganglion cells.

The P2X(3) receptor is a ligand-gated cation channel that is activated by extra cellular adenosine triphosphate (ATP) found in the dorsal root, trigeminal and nodose ganglia. It is one of the receptors transmitting nociceptive information of injuries and inflammation of the periphery by endogenous ATP released from damaged cells. The present study was performed in order to evaluate if there was an increased expression of P2X(3)-immunoreactivity in dorsal root ganglion (DRG) neurons after experimental disc herniation. There were four groups: exposure of the left L4 dorsal root ganglion and incision of the L4-L5 disc, exposure and slight displacement of the left L4 dorsal ganglion, sham exposure of the L4 dorsal root ganglion, and normal. Seven days after surgery, the DRG's were collected, sectioned and stained immunohistochemically for the P2X(3) receptor. The expression of P2X(3) increased significantly following incision of the L4-5 disc compared to the normal group. Sham surgery induced a minor, although statistically significant increase. Mechanical displacement did not induce any increased expression of the receptors. The study demonstrates that expression of the P2X(3)receptors in the DRG may be induced by local application of nucleus pulposus. This may increase our understanding of the pathophysiologic mechanisms related to disc herniation and sciatica.

Physical exercise affects cell proliferation in lumbar intervertebral disc regions in rats.

STUDY DESIGN: Descriptive experimental study. OBJECTIVE: The aim of this study was to investigate the effect of exercise on cell proliferation in different areas of the intervertebral disc (IVD) and recruitment of cells possibly active in regeneration of normal rat lumbar IVDs. SUMMARY OF BACKGROUND DATA: Little is known about the effects of physical exercise on lumbar IVD tissue. Recently, stem cell niches in the perichondrium area of the IVD were identified and cells in these niches have been suggested to be involved in the normal regeneration of the IVD. METHODS: Thirty Sprague-Dawley rats were exposed to 5-bromo-2-deoxyuridine (BrdU) diluted in the drinking water during 14 days. Fifteen rats ran on a treadmill daily for 50 min/d, 5 d/wk (exercise group), and 15 nonexercised rats served as controls. Immunohistochemical analyses (anti-BrdU antibody) were performed at 9, 14, 28, 56, and 105 days after the start of the exercise protocol. BrdU positive cells were counted in the stem cell niche area, the peripheral region of epiphyseal cartilage area, and the annulus fibrous outer and inner areas. Data were analyzed by 2-way analysis of variance (significance level; P < 0.05). RESULTS: The BrdU positive cell numbers in the stem cell niche and annulus fibrous outer regions were increased in discs from the exercising group on days 14 (P < 0.01) and 105 (P < 0.05) and at day 14 (P < 0.01) in the peripheral epiphyseal cartilage region compared with controls. CONCLUSION: Physical exercise was shown to have positive effects on cell proliferation in IVDs, with involvement of various disc regions, indicating a differential response by disc tissue to exercise depending on anatomical location and tissue characteristics.

Electron microscopy analysis of neurites extending from dorsal root ganglia in vitro following exposure to intervertebral disc cells.

Nucleus pulposus cells from the intervertebral disc have been shown to have inhibiting effects on neurite outgrowth in vitro. The nucleus pulposus consists of at least 2 cell populations, notochordal cells and chondrocyte-like cells. The aim of this study was to analyze the morphology of the neurites, from rat dorsal root ganglia (DRG) in a culture system, after exposure of these 2 cell populations. DRG from perinatal rats was harvested and placed in culture dishes for 24 h. Nucleus pulposus cells from donor rats were separated into 2 populations and applied to the DRG and neurite culture for a further 24 h and compared to control cultures exposed to culture medium without cells. The DRG and neurites were thereafter prepared for scanning or transmission electron microscopy (SEM/TEM). Descriptive SEM and TEM analyses and calculations of the neurite diameter were performed. The visual appearance after SEM and TEM preparation was similar in the three different culture conditions. However, there was a statistically significant reduction of the neurite diameter for the cultures exposed to notochordal cells compared to the cultures exposed to medium and chondrocyte-like cells (TEM preparation). Prominent and frequent pathologic abnormalities in peripheral nerve diseases have been observed with changes in axonal caliber. This study may suggest that a preserved small amount of notochordal cells, as seen in human adults, may play a role in clinical situations where nerve tissue is exposed to disc material, i.e. in disc herniation or degeneration.

Effect of methotrexate on fracture healing.

Low doses of methotrexate (MTX) are safe and effective for treating adult and juvenile rheumatoid arthritis. However, because this powerful anti-inflammatory drug might negatively influence the healing of wounds and fractures, MTX administration is often stopped during surgical procedures. The present study assesses the effects of low- and high-dose MTX on early inflammatory processes and bone healing in an experimental model of fracture. Thirty male Sprague-Dawley rats were assigned to low- and high-dose MTX and control groups. A femur was cut using a reciprocating saw and a 2-mm fracture gap was made using a fixator. One or four weeks thereafter, macrophages were immunostained and new bone formation was histomorphometrically measured. Significantly less new bone was formed in the high-dose MTX, than in the control group (p< 0.01), whereas bone formation did not significantly differ between the low-dose MTX and control groups. These results suggested that a low dose of MTX does not affect the early process of endochondral bone formation during fracture healing, whereas a high dose might delay the progress of new periosteal bone formation. Although more macrophages were found in the groups treated with MTX, their impact on surrounding inflammatory processes remains unclear.

Local application of interleukin-6 to the dorsal root ganglion induces tumor necrosis factor-α in the dorsal root ganglion and results in apoptosis of the dorsal root ganglion cells.

STUDY DESIGN: The mechanisms of apoptosis behind the formation of tissue reactions at the surface of the dorsal root ganglion (DRG) exposed to the nucleus pulposus were studied with special reference to the role of interleukin-6 (IL-6), using electron microscopy and immunohistochemistry in rats. OBJECTIVE: To study the role of IL-6 on the DRG. SUMMARY OF BACKGROUND DATA: It has been reported that nucleus pulposus cells are capable to produce proinflammatory cytokines, including tumor necrosis factor-alpha (TNF-α) and IL-6. Recently, it was observed that local application of nucleus pulposus induced a characteristic tissue reaction at the surface of the DRG. This change was due to apoptosis of DRG neurons. However, the role of IL-6 is not known regarding the apoptosis of the DRG neurons. METHODS: Recombinant IL-6 was applied between the L4 DRG and the dura to mimic a disc herniation of the L4-L5 disc in rats. The L4 DRGs were resected 24 hours after surgery. The sections were processed for immunohistochemistry using antisera to TNF-α. Furthermore, the sections of the specimens were observed using light and electron microscopy to confirm the induced apoptosis of the DRG neurons. The sections were also processed for immunohistochemistry, using antisera to single-stranded DNA (ssDNA) and Caspase 3. RESULTS: TNF-α immunoreactivity was observed in the peripheral area of DRG at the site of the application of IL-6. Typical changes of the cell nuclei were observed in the DRG by light and electron microscopy, indicating the presence of apoptosis. The presence of ssDNA and Caspase 3 further enhanced the impression that there was apoptosis of the DRG neurons. CONCLUSION: IL-6 seemed to induce TNF-α at the surface of DRG exposed to IL-6 and to induce a characteristic reaction at the surface of the DRG. IL-6 may thus play an important role in nucleus pulposus-induced apoptosis of the DRG neurons as well as TNF-α.

Effects of intervertebral disc cells on neurite outgrowth from dorsal root ganglion explants in culture.

STUDY DESIGN: An experimental study investigating the effect of disc cells on neurite outgrowth in a rat dorsal root ganglion (DRG) culture system. OBJECTIVE: To examine the effects of the 2 nucleus pulposus (NP) cell populations, notochordal cells (NC) and chondrocyte-like cells (CC) on neurite outgrowth from DRGs. SUMMARY OF BACKGROUND DATA: NP consists of at least 2 cell populations, NC and CC. The cells in NP have been shown to be responsible for negative effects on neurite outgrowth in vitro and on nerve tissue in vivo. It is unknown whether 1 cell type or combinations of the 2 cell types are responsible for the reported effects. METHODS: A total of 939 DRGs from newborn Sprague Dawley rats were harvested and placed in culture dishes. After 24 hours, the neurite outgrowth was measured. NP was harvested from tail discs of adult rats and the NP cells were separated into 2 populations, NC and CC. The cell populations were applied to the DRG culture in different cell concentrations and combinations, and compared to medium. After 24 hours of exposure, the neurite outgrowth was reassessed and expressed as the ratio between the outgrowth at 48 and 24 hours culture. RESULTS: NC in intermediate and high concentration and CC in high concentration induced a significant inhibition of the neurite outgrowth compared to culture medium. Further, one of the combinations (low NC and high CC concentration) resulted in a significant inhibition of the neurite outgrowth. CONCLUSION: The present study demonstrated negative effects of NP cells on nerve tissue culture explants. The combination of low NC and high CC concentrations may mimic the situation in humans, where we have an increased proportion of chondrocyte-like cells with age. The results from this study may provide a biologic explanation for the large variation of symptoms in disc herniation patients despite similar mechanical influence on nerve tissue.

Autologous nucleus pulposus primes T cells to develop into interleukin-4-producing effector cells: an experimental study on the autoimmune properties of nucleus pulposus.

An autoimmune response to herniated nucleus pulposus has been proposed to constitute a pathophysiologic mechanism for inducing sciatica based on the fact that nucleus pulposus under normal conditions is excluded from the development of immunological tolerance. The manifestation of an autoimmune response comprises different steps starting with antigen capture, continuing with activation of T helper (T(H)) cells and ending with production of autoantibodies. Activated T(H) cells differentiate into either T(H)1 cells, predominately producing proinflammatory cytokines such as interferon gamma (IFNgamma) or a T(H)2 subset mainly producing anti-inflammatory cytokines such as interleukin-4 (IL-4). The aim of the present study was to examine if exposure of autologous nucleus pulposus (NP) to the immune system for 3 weeks is potent enough to prime T(H) cells to differentiate into T(H)2 cells. The study was performed in a pig model allowing the exposure of NP to the immune system. To assess the polarization of T(H) cells the intracellular production of IFNgamma and IL-4 was measured in T cells by using flow cytometry. The revealed predominant production of IL-4 together with low production of IFNgamma in T cells after NP exposure to the immune system indicates that nucleus pulposus may prime T(H) cells to develop into IL-4-producing T(H)2 cells after being exposed to the immune system, for example, in association with disc herniation.

Osseointegrated trans-femoral amputation prostheses: prospective results of general and condition-specific quality of life in 18 patients at 2-year follow-up.

This is the first report on prospective outcome for individuals treated with bone-anchored trans-femoral amputation prostheses (OI-prostheses) using the method of osseointegration. The aim was to analyze general and condition-specific health related quality of life (HRQL) at 2-year follow-up as compared to the preoperative situation. The study population consists of the first 18 consecutively treated patients (8 male/10 female, mean age 45 years) in a clinical investigation with amputations mainly caused by trauma and tumour. At inclusion the mean time since the amputation was 15 years (10 months - 33 years). Two self-report questionnaires were answered preoperatively and at follow-up: the SF-36 Health Survey (SF-36) and the Questionnaire for persons with a Transfemoral Amputation (Q-TFA). At follow-up 17/18 patients used the OI-prosthesis; one did not due to pain and loosening of the implant. Four of the scales of the SF-36 (Physical Functioning, Role Functioning Physical, Bodily Pain and Physical Component Score) and all four scores of Q-TFA (Prosthetic Use, Prosthetic Mobility, Problems and Global Health) were statistically significantly improved at follow-up showing superior general physical HRQL, increased prosthetic use, better prosthetic mobility, fewer problems and a better global amputation situation. Thus, osseointegrated prostheses represent a promising development in the rehabilitation of individuals with transfemoral amputation and increase their quality of life.

The role of tumor necrosis factor-alpha in apoptosis of dorsal root ganglion cells induced by herniated nucleus pulposus in rats.

STUDY DESIGN: The mechanisms of apoptosis underlying a characteristic tissue reaction at the surface of the dorsal root ganglion (DRG) exposed to nucleus pulposus were studied in rats with special reference to the role of tumor necrosis factor-alpha (TNF). OBJECTIVE: To study the characteristic tissue reaction at the surface of the DRG exposed to nucleus pulposus with special reference to the role of TNF. SUMMARY OF BACKGROUND DATA: Nucleus pulposus cells are capable of producing TNF. Recently, local application of nucleus pulposus was shown to induce a characteristic tissue reaction at the DRG surface due to apoptosis. METHODS: Recombinant TNF was applied to the DRG to mimic L4-L5 disc herniation in rats. The DRGs were resected 24 hours after surgery. Sections of the specimens were processed for immunohistochemistry using antisera to single-stranded DNA, Caspase 3, and TNF, and observed by light and electron microscopy. RESULTS: Typical apoptotic changes of the cell nuclei were observed in the DRG after application of TNF. The presence of single-stranded DNA, Caspase 3, and TNF further confirmed the occurrence of DRG cell apoptosis. CONCLUSION: TNF seemed to play a key role in induction of apoptosis of DRG cells, which resembled that induced by application of nucleus pulposus.

Autoimmune properties of nucleus pulposus: an experimental study in pigs.

STUDY DESIGN: Assessment of activated T and B cells in a subcutaneous chamber filled with autologous nucleus pulposus using flow cytometry and immunohistochemistry. OBJECTIVES: To examine if subcutaneously placed autologous nucleus pulposus may attract activated T and B cells in an animal model. SUMMARY OF BACKGROUND DATA: Nucleus pulposus has been suggested to trigger an autoimmune response if exposed to the immune system, for example, in association with disc herniation. T-cell activation represents a hallmark in the generation of an autoimmune response, subsequently leading to the differentiation of B cells, but a causal association between the exposure of nucleus pulposus to the systemic circulation and T and B cell activation is still lacking. METHODS: Autologous nucleus pulposus was harvested from the intervertebral disc of 9 pigs and placed subcutaneously in perforated titanium chambers. In order to control for the effect of the titanium chamber, an additional empty chamber was placed subcutaneously in each pig. After 7 days, the pigs were killed and the chambers were harvested. Flow cytometry and immunohistochemistry were used for analysis of T-helper cells (CD4+), cytotoxic T cells (CD8+), and B cells (Igkappa) in the chamber exudates and T cells (CD45RC) in the remaining blood clot tissue of the chamber. RESULTS: As compared with the empty chambers, the proportion of activated T cells (CD4+ and CD8+) was significantly higher in the exudate of the nucleus pulposus filled chamber. The proportion of activated B cells expressing immunoglobulin kappa (Igkappa) was also significantly elevated in the exudate of the nucleus pulposus chambers. The analysis of the remaining chamber tissue revealed a significantly higher amount of T cells (CD45RC) in the nucleus pulposus chambers than in the empty chambers. CONCLUSIONS: The present findings indicate that nucleus pulposus attracts activated T and B cells. However, since the cell population in the nucleus pulposus of young pigs may differ from that of adult humans, the obtained data may not be directly transferred to the human situation of a disc herniation. The observations in the present study may nevertheless explain some of the local tissue reactions occurring in association with disc herniation and nerve root involvement, thereby providing further insight into the pathophysiology of sciatica.