Revision total knee arthroplasty longer term outcome and comparison between infection and aseptic loosening at mean follow-up of 10 years

Background:

Although the majority of total knee arthroplasty cases have good outcome and survival, some arthroplasty eventually required revision. While early outcomes of revision knee arthroplasty are well reported, there is relatively fewer literatures reporting on the longer term outcome of revision knee arthroplasty. This study aims to review the outcome of revision knee arthroplasty for a longer term, and also make comparison between the two common indications for revision arthroplasty of infection and aseptic loosening.

Methods:

This study reviews all total knee arthroplasty revision performed at a single center over a 11 year period. Of the 48 cases found, 35 cases not lost to follow-up had a mean follow-up duration of 10.6 years (SD 2.9) for aseptic loosening, and 10.1 years (SD 2.6) for infection. Data of initial arthroplasty, revision arthroplasty, demographics, follow-up outcome were obtained, analyzed and compared.

Results:

Revision arthroplasty due to infection had more cases that required use of varus/valgus constraints (p ∼ 0.008) and extensile surgical exposure of quadriceps snip (p ∼ 0.005) compared to aseptic loosening. The survival at 10 years for this study is 91% overall (aseptic loosening 93.3%, infection 89.3%). Infection cases had significant initial improvement for range of motion (p ∼ 0.001) and use of walking aid (p ∼ 0.04) at post-operation 1 year, but no significant differences between the infection and aseptic loosening cases at 5 years and 10 years follow-up. Comparison between the two groups on other factors including initial arthroplasty, operative details, demographics, post-operative details and X-rays showed no statistically significant difference.

Casting versus percutaneous pinning for extra-articular fractures of the distal radius in an elderly Chinese population: a prospective randomised controlled trial

We carried out a prospective randomised controlled clinical trial to compare the functional and radiological outcomes of casting with percutaneous pinning in treating extra-articular distal radial fracture in an elderly Chinese population. Sixty patients were randomly allocated by sealed envelopes to either a 'Cast' group (n = 30) or a 'K-wire' group (n = 30). All patients were available for final follow-up assessment. The radiological outcomes in terms of dorsal angulation, radial inclination and radial length were statistically significantly better in the K-wire group, whereas the Mayo wrist score and quality of life, healing rate, healing time, and complications were similar. The functional outcomes and quality of life were not affected by the treatments. Both treatments had a very low rate of complication and high healing rates.

A novel sulfate reduction, autotrophic denitrification, nitrification integrated (SANI) process for saline wastewater treatment

This paper reports on a lab-scale evaluation of a novel and integrated biological nitrogen removal process: the sulfate reduction, autotrophic denitrification and nitrification integrated (SANI) process that was recently proposed for saline sewage treatment. The process consisted of an up-flow anaerobic sludge bed (UASB) for sulfate reduction, an anoxic filter for autotrophic denitrification and an aerobic filter for nitrification. The experiments were conducted to evaluate the performance of the lab-scale SANI system with synthetic saline wastewater at various hydraulic retention times, nitrate concentrations, dissolved oxygen levels and recirculation ratios for over 500 days. The system successfully demonstrated 95% chemical oxygen demand (COD) and 74% nitrogen removal efficiency without excess sludge withdrawal throughout the 500 days of operation. The organic removal efficiency was dependent on the hydraulic retention time, up-flow velocity, and mixing conditions in the UASB. Maintaining a sufficient mixing condition in the UASB is important for achieving effective sulfate reduction. For a typical Hong Kong wastewater composition 80% of COD can be removed through sulfate reduction. A minimum sulfide sulfur to nitrate nitrogen ratio of 1.6 in the influent of the anoxic filter is necessary for achieving over 90% nitrate removal through autotrophic denitrifiers which forms the major contribution to the total nitrogen removal in the SANI system. Sulfur balance analyses confirmed that accumulation of elementary sulfur and loss of hydrogen sulfide in the system were negligible.

A novel sludge minimized biological nitrogen removal process for saline sewage treatment

This study reports a lab-scale evaluation of a new biological nitrogen removal process for saline sewage treatment, namely a SANI process (Sulfate reduction, Autotrophic denitrification and Nitrification Integrated process). The experimental system consisted of an up-flow anaerobic bed for sulfate reduction, an anoxic filter for autotrophic denitrification using dissolved sulfide produced in the up-flow anaerobic bed and an aerobic filter for nitrification. The system successfully operated for more than 180 days with an overall organic carbon removal efficiency of 95%, in which, 82% removal was contributed by the up-flow anaerobic bed operating at a HRT of 6 h, and 13% removal by the anoxic filter. An average COD removed /sulfate removed ratio was found to be 0.76 gCOD/gSO(4) or 2.28 COD/gSO(4)-S further confirming that the organic removal was mainly achieved by the sulfate reduction. In terms of nitrogen removal efficiency, the SANI system was found sensitive to the recirculation rate between the anoxic filter and the aerobic filter. A recirculation rate of 3Q was found to be optimal for achieving 74% of the total nitrogen removal. It was confirmed that the autotrophic denitrification was a major contributor to the total nitrogen removal in the SANI system. Sulfur balance analysis indicated that both the accumulation of elementary sulfur in the biomass and the loss of hydrogen sulfide were trivial. During the entire operation period (330 days to date), no sludge was wasted from any reactors in this system. This was further confirmed by the biomass balance simulation results that low biomass yields of sulfate reducing bacteria, autotrophic denitrifiers and nitrifiers contribute to the zero excess sludge discharge.

Conventional muscle-reflection approach versus mini-incision muscle-splitting approach in dynamic hip screw fixation

PURPOSE

To compare the short-term results of conventional versus mini-incision approaches to dynamic hip screw (DHS) fixation.

METHODS

41 geriatric patients with either basal femoral neck or intertrochanteric fractures (Kyle types I to III) who underwent closed reduction and DHS fixation by a single surgeon were retrospectively reviewed. From January 2001 to June 2005, 6 men and 19 women aged 60 to 94 (median, 83) years underwent DHS fixation through a conventional muscle-reflection approach with a skin incision of 10 cm or more. From July 2005 to March 2006, 9 men and 7 women aged 67 to 95 (median, 81) years underwent DHS fixation through a mini-incision (4 cm) approach at the lower border of the lesser trochanter. Operating time, drain output and duration of drain placement, decrease in haemoglobin level and receipt of blood transfusions, deterioration in ambulation status, analgesic intake, duration of hospital stay, and bone healing time for the 2 groups were compared. An independent observer retrospectively assessed the fracture pattern, reduction quality, and bone healing time.

RESULTS

Compared to patients in the conventional group, those in the mini-incision group had shorter operating times (50 vs 43 minutes, p=0.02), a higher proportion whose drain was removed within 24 hours (28% vs 69%, p=0.01), and consumed fewer dosages of oral analgesics within 48 hours (8 vs 5, p=0.001). Classification of the fracture pattern in 21 of 38 patients were consistent between the surgeon and observer. The Kappa value for agreement was 0.32, denoting marginal agreement (p=0.003). Reduction quality (p=0.66) and bone healing time (p=0.73) assessed by the observer were not significantly different between the 2 groups.

CONCLUSION

The short-term clinical outcome of mini-incision DHS fixation for geriatric pertrochanteric fractures was favourable.

Medial humeral epicondylar fracture in children and adolescents

PURPOSE

To assess treatment outcomes of young patients with medial epicondylar fracture of the elbow using standard operative protocols.

METHODS

24 consecutive patients with medial humeral epicondylar fracture underwent surgery by one of the 3 methods: (1) 2 parallel Kirschner wires, (2) 2 parallel Kirschner wires plus a tension-band wire, and (3) a screw plus an anti-rotation Kirschner wire. Fractures displaced less than 5 mm were treated conservatively (casting for 3 weeks). Outcome was assessed clinically and radiologically. The Mayo Clinic Elbow Performance Index was measured.

RESULTS

The 3 patients with undisplaced fractures had good radiological results and scores. One patient with a displaced fracture refused surgery and subsequently developed pseudarthrosis and cubitus valgus. All operatively treated patients had good scores, but 2 treated with 2 parallel Kirschner wires alone developed pseudarthrosis. Patients in this group needed longer rehabilitation to attain a functional range of movement than those in other groups (treated together with a tension-band wire or screw).

CONCLUSION

Surgery is recommended for children with displaced medial epicondylar fractures of more than 5 mm. The use of a tension-band wire, instead of a screw, together with Kirschner wires is the preferred treatment for younger children.

Early results of posterior-stabilised NexGen Legacy total knee arthroplasty

OBJECTIVE

To retrospectively assess the early results of the NexGen Legacy posterior-stabilised total knee prosthesis, which is a newer version of the Insall-Burstein II posterior-stabilised implant.

METHODS

48 consecutive elderly patients had 60 NexGen Legacy posterior-stabilised total knees. The mean follow-up duration was 21 months. Clinical evaluation was performed according to the Knee Society scores and a scoring system for patellofemoral articulation; radiographic assessment followed the guidelines of the Knee Society. Special emphasis was given to any patellofemoral complications, such as patellar clunk syndrome, patellar maltracking, and other disorders of the extensor mechanism.

RESULTS

Only one patient had mild patellofemoral anterior knee pain at the latest follow-up; 2 patients had patellofemoral crepitus but no pain. No patellar clunk or any other complication of the patellofemoral articulation, such as patellar fracture or subluxation was found. The mean preoperative and postoperative Knee Society scores were 60 and 85 respectively. The mean postoperative knee flexion was 115 degrees.

CONCLUSION

The overall early results from using the new implant were good, probably because of changes in design of the intercondylar box and its associated cam-and-post mechanism, and a more anatomic trochlea surface, so that the trochlea accommodates the natural patella.

Sealing the intramedullary femoral canal with autologous bone plug in total knee arthroplasty

In a prospective study of 262 consecutive patients with total knee arthroplasty, we compared the postoperative suction drainage and transfusion requirement in cases in which the defect made by the femoral intramedullary rod was either unplugged (n = 134) or plugged (n = 128). All operations were performed with a single surgical approach and technique. Inflammatory arthritis and lateral releases were excluded. Blood loss was recorded at 24, 48, and 72 hours. The difference in postoperative suction drainage was not statistically significant. The hemoglobin decrease in the unplugged group (3.5 g/dL) was different from that in the plugged group (2.3 g/dL) (P<.05). Of patients, 64.4% (n = 85) in the unplugged group and 35.9% (n = 46) in the plugged group required transfusion (P<.05). Sealing the femoral canal is effective in reducing hemoglobin decrease and blood transfusion in total knee arthroplasty.

Comparison of two total knee prostheses on the incidence of patella clunk syndrome

The patella clunk syndrome is not an uncommon complication, particularly after posterior-stabilized (PS) total knee arthroplasty. The present study was a consecutive unselected series comparing the incidence of the patella clunk syndrome amongst two comparable groups of elderly patients with knee arthritis implanted with the Insall-Burstein (IB II) total knee system and the newer NexGen Legacy total knee prosthesis. While 7.5% of patients in the PS IB II group developed patella clunk syndrome, none occurred in the NexGen group (P=0.05). We believe the difference is due mainly to a change in the design of the prosthesis, especially the more posterior intercondylar box and femoral cam of the NexGen femoral component.

Axon-glial relations during regeneration of axons in the adult rat anterior medullary velum

The anterior medullary velum (AMV) of adult Wistar rats was lesioned in the midsagittal plane, transecting all decussating axons including those of the central projection of the IVth nerve. At selected times up to 200 days after transection, the degenerative and regenerative responses of axons and glia were analyzed using transmission and scanning electron microscopy and immunohistochemistry. In particular, both the capacity of oligodendrocytes to remyelinate regenerated fibers and the stability of the CNS/PNS junctional zone of the IVth nerve rootlet were documented. Transected central AMV axons exhibited four patterns of fiber regeneration in which fibers grew: rostrocaudally in the reactive paralesion neuropil (Group 1); randomly within the AMV (Group 2); into the ipsilateral IVth nerve rootlet, after turning at the lesion edge and growing recurrently through the old degenerated contralateral central trochlear nerve trajectory (Group 3); and ectopically through paralesion tears in the ependyma onto the surface of the IVth ventricle (Group 4). Group 1-3 axons regenerated unperturbed through degenerating central myelin, reactive astrocytes, oligodendrocytes, microglia, and large accumulations of hematogenous macrophages. Only Group 3 axons survived long term in significant numbers, and all became myelinated by oligodendrocytes, ultimately establishing thin sheaths with relatively normal nodal gaps and intersegmental myelin sheath lengths. Schwann cells at the CNS/PNS junction of the IVth nerve rootlet did not invade the CNS, but astrocyte processes grew across the junction into the PNS portion of the IVth nerve. The basal lamina of the junctional glia limitans remained stable throughout the experimental period.