Biomechanical considerations in ‘biological’ femoral osteosynthesis: an experimental study of the ‘bridging’ and ‘wave’ plating techniques

Although traditional compression plate fixation aims to abolish interfragmentary movement and achieve primary bone healing, the more recent ‘biological’ plate fixation methods such as the ‘bridging’ and ‘wave’ plate techniques aim to maintain fracture alignment without absolute stability and promote union by callus formation. Furthermore, some mechanical advantages have been attributed to the ‘wave’ plate fixation. Since no data have been published on the mechanical characteristics of the ‘bridging’ and ‘wave’ plate fixation methods, the aim of this biomechanical comparative study was to investigate the rigidity of those fixation methods in various types of femoral diaphyseal fractures. Using a composite femoral model, the rigidity characteristics of three fixation methods (short DCP, ‘bridging’ and ‘wave’ plates) were investigated. The results showed that when cortical contact between the main fragments is present, a ‘bridging’ plate can be equally rigid to the ‘wave’ plate in mediolateral bending by displaying a similar tension-band effect. Furthermore, in the absence of cortical contact, the axial fixation rigidity of the long ‘bridging’ plate is superior to that of the ‘wave’ plate. Both methods showed a significant ‘stress-shielding’ effect on the intact femur. In conclusion, this in vitro study failed to show any significant mechanical advantages of the ‘wave’ plate technique over the ‘bridging’ plating method. It appears that the ‘bridging’ plate fixation may be the mechanically optimal ‘biological’ plating method for the femoral diaphysis. Received: 26 May 1999     

Definitional Differences of ‘Outpatient’ Versus ‘Inpatient’ THA and TKA Can Affect Study Outcomes

Background

There has been great interest in performing outpatient THA and TKA. Studies have compared such procedures done as outpatients versus inpatients. However, stated “outpatient” status as defined by large national databases such as the National Surgical Quality Improvement Program (NSQIP) may not be a consistent entity, and the actual lengths of stay of those patients categorized as outpatients in NSQIP have not been specifically ascertained and may in fact include some patients who are “observed” for one or more nights. Current regulations in the United States allow these “observed” patients to stay more than one night at the hospital under observation status despite being coded as outpatients. Determining the degree to which this is the case, and what, exactly, “outpatient” means in the NSQIP, may influence the way clinicians read studies from that source and the way hospital systems and policymakers use those data.

Questions/Purposes

The purposes of this study were (1) to utilize the NSQIP database to characterize the differences in definition of “inpatient” and “outpatient” (stated status versus actual length of stay [LOS], measured in days) for THA and TKA; and (2) to study the effect of defining populations using different definitions.

Methods

Patients who underwent THA and TKA in the 2005 to 2014 NSQIP database were identified. Outpatient procedures were defined as either hospital LOS = 0 days in NSQIP or being termed “outpatient” by the hospital. The actual hospital LOS of “outpatients” was characterized. “Outpatients” were considered to have stayed overnight if they had a LOS of 1 day or longer. The effects of the different definitions on 30-day outcomes were evaluated using multivariate analysis while controlling for potential confounding factors.

Results

Of 72,651 patients undergoing THA, 529 were identified as “outpatients” but only 63 of these (12%) had a LOS = 0. Of 117,454 patients undergoing TKA, 890 were identified as “outpatients” but only 95 of these (11%) had a LOS = 0. After controlling for potential confounding factors such as gender, body mass index, functional status before surgery, comorbidities, and smoking status, we found “inpatient” THA to be associated with increased risk of any adverse event (relative risk, 2.643, p = 0.002), serious adverse event (relative risk, 2.455, p = 0.011), and readmission (relative risk, 2.775, p = 0.010) compared with “outpatient” THA. However, for the same procedure and controlling for the same factors, patients who had LOS > 0 were not associated with any increased risk compared with patients who had LOS = 0. A similar trend was also found in the TKA cohort.

Conclusions

Future THA, TKA, or other investigations on this topic should consistently quantify the term “outpatient” because different definitions, stated status or actual LOS, may lead to different assignments of risk factors for postoperative complications. Accurate data regarding risk factors for complications after total joint arthroplasty are crucial for efforts to reduce length of hospital stay and minimize complications.

Level of Evidence

Level III, therapeutic study.

     

Low probability of Significant Intra-Abdominal Injury in Stable Patients with Abdominal ‘‘Seat Belt Sign’’

Abstract Study Objective:   Our aim was to determine the diagnostic significance of the association between the abdominal skin bruise from a seat belt and the presence of intraabdominal injury. Methods:   This was an observational analysis of prospectively collected data on 45 patients who presented with an abdominal seat belt sign to a level 1 trauma center following a motor vehicle accident between July 2004 and December 2007. The patients were evaluated by computed tomography (CT) scans or ultrasonography (FAST), depending on their hemodynamic stability. They were then hospitalized for treatment or observation. Results:   Forty-five patients [23 males (51.1%) and 22 females (48.9%)], with a mean age of 32.2 years (range 16–80 years), fulfilled entry criteria and were enrolled. Of these, 44 (97.8%) underwent CT, and one (2.2%) underwent FAST due to hemodynamic instability. two patients (4.4%) had intraabdominal injuries: one required surgery for bowel injury, and the other had a minor liver laceration, which was managed expectantly. Sixteen patients (35.5%) had concomitant injuries. The length of hospital stay ranged from 1–23 days (median 2.2 days). Conclusions:   Despite the widely accepted view that patients with an abdominal seat belt sign are more likely to have serious intraabdominal injuries, the results of our investigation showed no such association in a group of hemodynamically stable patients.     

The ‘antiphospholipid syndrome’ and the ‘lupus anticoagulant’

In recent years an association has been described between, on the one hand, an in vitro prolongation of phospholipid-dependent coagulation tests (the lupus anticoagulant) or the demonstration of antiphospholipid antibodies and, on the other, clinical events, particularly recurrent thrombosis (usually venous but sometimes arterial), thrombocytopenia, and also recurrent mid-term fetal loss. Other less well-documented associations with haemolytic anaemia, livedo reticularis, strokes and other neurological syndromes have been suggested. The antibodies are present temporarily in many infections, are usually of IgM isotype and thrombosis does not occur. However, they are persistently present and mainly of IgG isotype in a number of auto-immune disorders associated with thrombosis, in particular systemic lupus erythematosus, in which 50% of patients will show antibody of one isotype or another. The strongest association is with antinuclear factor-negative lupus and lupus-like disorders in which a full diagnosis of classical lupus cannot be made. The clotting test abnormality and antiphospholipid antibodies may be found also in otherwise normal individuals suffering thrombosis or fetal loss — the so-called primary antiphospholipid syndrome. These data raise important questions for management, but many details are controversial despite a decade's work; this review examines the present position and outlines some of the difficulties, particularly from the point of view of nephrology and paediatrics.     

The bridging of large osteoperiosteal gaps using ‘Decalbone’

Summary Decalbone was prepared by partial decalcification of human bones obtained from recently amputated specimens. It was then stored in 80 to 90% ethanol in a domestic refrigerator. The decalbone was used to fill large osteoperiosteal gaps in 25 patients. The commonest lesion was a giant cell tumour (21 cases) and various long bones were affected. There were 6 failures with recurrence of the tumour in 3 and uncontrolled infection in 3. The remaining 19 cases were followed up for from 2 1/2 to 7 years. In 10 the decalbone incorporated well, but further reconstructive procedures were needed in 9. Our studies showed that incorporation began at around 6 to 9 months and was complete at about 2 years in the upper limb and 4 years in the lower limb. There was no clinical evidence of an immune response.

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Résumé Le «Decalbone» provient de la décalcification partielle d'os humains obtenus à partir de pièces d'amputation récentes. Ils sont ensuite conservés dans l'éthanol à 80 ou 90% dans un réfrigérateur usuel. Le Decalbone a été utilisé pour combler de vastes pertes de substance chez 25 malades. La lésion la plus fréquente était la tumeur à cellules géantes (21 cas) et divers os longs étaient atteints. Il y a eu 6 échecs, 3 par récidive tumorale et 3 par infection. Les 19 autres cas ont été suivis de 2 ans et demi à 7 ans. Dix fois le Decalbone s'est parfaitement incorporé, mais 9 fois il a fallu recourir à d'autres procédés de reconstruction. Nos observations montrent que l'incorporation débute entre le 6e et le 9e mois et qu'elle est complète vers la 2e année au membre supérieur et vers la 4e au membre inférieur. Il n'y a jamais eu de problèmes immunologiques.

     

The ‘mirrored’ Bennett fracture of the base of the fifth metacarpal

Fractures of the base of the metacarpals are usually treated conservatively. The intra-articular fracture of the base of the first metacarpal (‘Bennett fracture’) is an exception to this rule because inadequate repositioning and fixation of the dislocated radial fragment lead to permanent deformity of the joint and subsequent degenerative joint disease. The dislocated intra-articular fracture of the base of the fifth metacarpal is similar to a Bennett fracture in many aspects. Repositioning of this ‘mirrored’ Bennett fracture cannot be guaranteed by a plaster cast. Inadequate repositioning will lead to pain, reduced strength and early degenerative joint disease. We present six patients with dislocated intra-articular fractures of the base of the fifth metacarpal to illustrate the necessity of surgical reduction and fixation. Received: 20 June 1999     

The diagnosis and treatment of the ‘mixed’ type of depressed fractures of the calcaneum

Summary The mixed type of depressed fractures of the calcaneum is described and a classification proposed. During a six year period, 78 patients with fractures of the calcaneum were seen. Of these 32 were of the mixed type and 23 were treated by sub-talar arthrodesis and restoration of the calcaneal outline. Very good or good results were obtained in all patients subjected to operation.

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Résumé L'auteur décrit un type de fracture du calcanéum par enfoncement «mixte» (i. e. à la fois vertical et horizontal) et il en propose une classification. Sur 78 fractures du calcanéum observées en six ans, 32 étaient de ce type «mixte» et 23 d'entre elles furent traitées par arthrodèse sous-astragalienne avec reconstitution de la forme du calcanéum. D'excellents ou de bons résultats ont été obtenus chez tous les blessés qui ont bénéficié de cette intervention.