Does stem design influence component positioning in total hip arthroplasty using a minimal invasive posterolateral approach?

Purpose

Limited data exist for the reconstructive potential of short bone-preserving stems in THA using a minimal invasive posterolateral approach. Our study aim was to assess the effect of stem design on the reconstruction of hip offset and leg length in MIS posterolateral THA.

Methods

This retrospective consecutive single-surgeon study compares hip offset and leg length, as well as acetabular component positioning (cup anteversion; inclination) of 129 THAs with a cementless standard-length stem (Synergy®) and 143 THAs with a cementless short bone-preserving stem (Trilock®).

Results

In reference to the contralateral side, the mean difference in hip offset was 0.9 mm (p = 0.067) for the standard stem and 0.1 mm (p = 0.793) for the short stem, respectively. Leg-length discrepancy was 0.7 mm (Synergy®) and 0.9 mm (Trilock®), respectively. A total of 233 (86 %) acetabular components fell within the target zone for anteversion and inclination.

Conclusion

Accurate component positioning in MIS posterolateral approach THA is possible and is not influenced by the type of stem.     

Influencing factors for the increased stem version compared to the native femur in cementless total hip arthroplasty

Purpose

Stem version is not always equivalent to femoral neck version (native version) in cementless total hip arthroplasty (THA). We therefore examined the discrepancy of version between the native femoral neck and stem using pre- and postoperative computed tomography (CT), the level of the femur where the canal version most closely fit the stem version, and the factors influencing version discrepancy between the native femoral neck and stem.

Methods

A total of 122 hips in 122 patients who underwent primary THA using a metaphyseal-fit stem through the postero-lateral approach were included. Pre- and postoperative CT images were utilized to measure native and stem version, and the version of the femoral canal at four levels relative to the lesser trochanter.

Results

The mean native and stem versions were 28.1 ± 11.0° and 38.0 ± 11.2°, respectively, revealing increased stem version with a mean difference of 9.8° (p < 0.0001). A total of 84 hips (68.9 %) revealed an increase in version greater than 5°. Femoral canal version at the level of the lesser trochanter most closely approximated that of stem version. Among the factors analysed, both univariate and multivariate analysis showed that greater degrees of native version and anterior stem tilt significantly reduced the version discrepancy between the native femoral neck and stem version.

Conclusions

Since a cementless stem has little version adjustability in the femoral canal, these findings are useful for surgeons in preoperative planning and to achieve proper component placement in THA.     

Radiographic quantification of dynamic hip screw migration

Purpose

This study aimed to propose a technique to quantify dynamic hip screw (DHS®) migration on serial anteroposterior (AP) radiographs by accounting for femoral rotation and flexion.

Methods

Femoral rotation and flexion were estimated using radiographic projections of the DHS® plate thickness and length, respectively. The method accuracy was evaluated using a synthetic femur fixed with a DHS® and positioned at pre-defined rotation and flexion settings. Standardised measurements of DHS® migration were trigonometrically adjusted for femoral rotation and flexion, and compared with unadjusted estimates in 34 patients.

Results

The mean difference between the estimated and true femoral rotation and flexion values was 1.3° (95 % CI 0.9–1.7°) and −3.0° (95 % CI – 4.2° to −1.9°), respectively. Adjusted measurements of DHS® migration were significantly larger than unadjusted measurements (p = 0.045).

Conclusion

The presented method allows quantification of DHS® migration with adequate bias correction due to femoral rotation and flexion.

Electronic supplementary material

The online version of this article (doi:10.1007/s00264-013-2146-4) contains supplementary material, which is available to authorised users.     

Implementing a clinical pathway for hip fractures; effects on hospital length of stay and complication rates in five hundred and twenty six patients

Purpose

Modern management of the elderly with a hip fracture is complex and costly. The aim of this study was to compare the treatment-related hospital length of stay (HLOS) before and after implementing a clinical pathway for patients undergoing hip fracture surgery.

Methods

This was a retrospective, before-and-after study. The first period ranged from June 21, 2008 to November 1, 2009 (N = 212), and the second was from January 7, 2010 to July 7, 2011 (N = 314). The electronic hospital system and patients records were reviewed for demographics, HLOS, mortality, complications and readmissions.

Results

In the first period 53 % had a femoral neck fracture, of which 57 % were treated with hemiarthroplasty. In the second period this was 46 % and 71 %. Pertrochanteric fractures were treated with a Gamma nail in 85 % in the first period, and in 92 % in the second period. The median HLOS decreased from nine to six days (p < 0.001). For the hemiarthroplasty group HLOS decreased from nine to seven days (p < 0.001); for internal fixation there was no significant difference (five versus six days, p = 0.557) and after Gamma nailing it decreased from ten to six days (p < 0.001). For mortality no statistically significant difference was found (6 % versus 5 %, p = 0.698). Complications decreased for the Gamma nail group (44 % versus 31 %, p = 0.049). Readmissions for the total group were not different (16 % versus 17 %, p = 0.720).

Conclusions

Implementing a clinical pathway for hip fractures is a safe way to reduce the HLOS and it improves the quality of care.     

Does total hip arthroplasty restore native hip anatomy? Three-dimensional reconstruction analysis

Purpose

Component orientations and positions in total hip arthroplasty (THA) are important parameters in restoring hip function. However, measurements using plain radiographs and 2D computed tomography (CT) slices are affected by patient position during imaging. This study used 3D CT to determine whether contemporary THA restores native hip geometry.

Methods

Fourteen patients with unilateral THA underwent CT scan for 3D hip reconstruction. Hip models of the nonoperated side were mirrored with the implanted side to quantify the differences in hip geometry between sides.

Results

The study demonstrated that combined hip anteversion (sum of acetabular and femoral anteversion) and vertical hip offset significantly increased by 25.3° ± 29.3° (range, −25.7° to 55.9°, p = 0.003) and 4.1 ± 4.7 mm (range, −7.1 to 9.8 mm, p = 0.009) in THAs.

Conclusions

These data suggest that hip anatomy is not fully restored following THA compared with the contralateral native hip.     

Atypical femoral fractures after anti-osteoporotic medication: a Korean multicenter study

Purpose

Increasing numbers of atypical femoral fractures have been reported among long-term bisphosphonate users. We evaluated clinical characteristics of atypical femoral fractures throughout Korean multicenter studies.

Methods

We retrospectively analysed the bone mineral density, prodromal symptoms before femoral fracture, and medication history of osteoporosis in 76 cases of atypical femoral fracture.

Results

The mean age of cases was 71.4 ± 8.8 (range, 43–89) years old. The mean follow-up period after the fracture operation was 24.5 ± 12.9 (range, 12–79) months. BMI was 23.2 ± 3.0 on average. The mean BMD of femur was −1.9 ± 1.4 (range, −4.8 to 1.3). Prodromal symptoms including thigh pain before femoral fracture appeared in 22 (28.9 %) of 76 patients. All patients included in the study used bisphosphonate. The duration of taking bisphosphonate before fracture was 36.8 ± 50.8 (one–204 months) months. Fifty-seven (75 %) of 76 patients were taking the medication for more than three years. Delayed union occurred in 43 (56.5 %) of 76 patients. Delayed union was defined as a fractured bone that did not completely heal within six months of injury. The group of having taken anti-osteoporotic medication for more than three years showed relatively longer union period compared to that for a shorter period medication group (4.8 ± 2.5 months vs 9.3 ± 3.7 months, p = 0.017). The delayed union developed in 43 (56.5 %) of 76 patients and showed a significantly higher incidence in the group with long-term therapy (five/43 vs 38/43, p = 0.021). The bilateral femoral fractures developed in 23 (30.2 %) of 76 patients and showed a high incidence in the group medicated more than three years (two/23 vs 21/23, p = 0.039).

Conclusions

The longer bisphosphonates are used, the more the cases of delayed union and the more frequent the development of bilateral fractures following unilateral fractures. With regard to the delayed union, the methods of the acceleration of fracture healing may be beneficial in atypical femoral fracture patients who had been receiving long-term bisphosphonates therapy. Careful observation is required for contra-lateral femurs due to a high incidence of bilateral atypical femoral fractures.     

Endothelial nitric oxide synthase gene intron 4 polymorphism in non-traumatic osteonecrosis of the femoral head

Purpose

Nitric oxide (NO) synthesised by endothelial NO synthase (eNOS) is a potent regulator of internal haemodynamics. A polymorphism in intron 4 of the eNOS is associated with different vascular disorders. We investigated the potential involvement of this polymorphism in idiopathic and secondary osteonecrosis of the femoral head (ONFH) in Polish patients.

Methods

We performed a study involving 68 patients with ONFH (45 idiopathic and 23 secondary) and 100 healthy controls. All subjects were genotyped for the eNOS4 polymorphism by the polymerase chain reaction followed by agarose gel electrophoresis.

Results

The analysis revealed that the frequencies of eNOS4 genotypes were significantly different in ONFH patients (both idiopathic and secondary) than in controls. The frequencies of the 4a allele were significantly higher in the total group of patients versus controls [22.79 vs 9 %, p = 0.00039, odds ratio (OR) 2.98]. In subgroup analysis the 4a allele increased significantly in both idiopathic (20 vs 9 %, p = 0.0074, OR = 2.52) and secondary (28.26 vs 9 %, p = 0.00047, OR = 3.98) ONFH patients compared to control subjects. The frequency of the 4a/b genotype in the total group of patients (36.76 vs 16 %, p = 0.0011, OR = 3.24) as well as patients with idiopathic (35.56 vs 16 %, p = 0.0069, OR = 2.96) and secondary (39.13 vs 16 %, p = 0.0073, OR = 3.89) ONFH was higher than in the control group.

Conclusions

There was a significantly higher frequency of eNOS 4a allele carriers among the total group of patients as well as in idiopathic and secondary ONFH. This suggests that the eNOS gene polymorphism may be associated with increased risk of ONFH.     

Improved outcomes after anterior cruciate ligament reconstruction with quadrupled hamstring autografts and additional bone plug augmentation at five year follow-up

Purpose

Hybrid fixation has been proposed to improve outcomes of anterior cruciate ligament (ACL) reconstructions. This study evaluated midterm outcomes after transfemoral graft fixation using either a conventional or a modified technique using additional bone plug augmentation (BPA) of the femoral tunnel aperture.

Methods

Seventy-one consecutive patients undergoing ACL reconstruction using a quadrupled hamstring autograft with transfemoral graft fixation and tibial interference screw fixation were included. Of these, 56 patients could be followed up 61 months (range 52–69 months) after ACL reconstruction both clinically and by magnetic resonance imaging (group A, conventional technique, n = 34; group B, modified technique, n = 22). Anteroposterior (AP) laxity measurements and International Knee Documentation Committee (IKDC), Lysholm and Tegner activity scoring were performed, while imaging included assessment of bone tunnel diameters, graft condition and graft filling at the femoral bone tunnel aperture.

Results

Patients with additional BPA had a significantly higher degree of graft filling at the femoral bone tunnel aperture (p = .0135) and ‘healthier’ grafts (p = .0495). They also tended to display less AP laxity difference in terms of mean differences and total patient numbers. Lysholm, IKDC and Tegner activity index scores and bone tunnel diameters were not significantly different.

Conclusions

Additional BPA is an easy-to-perform, cheap and safe manoeuvre, which has the capacity to improve morphological and clinical outcomes at five year follow-up. However, femoral tunnel widening is unaffected by additional BPA.     

Prosthetic radial head stem pull-out as a mode of failure: a biomechanical study

Purpose

Press-fit cementless radial head implant longevity relies on adequate bone ingrowth. Failed implant osseointegration remains a clinical concern and has been shown to lead to prosthetic failure. The purpose of this study was to test the hypothesis that implants with sufficient initial press-fit stability would be less likely to fail due to implant pull-out, as demonstrated by an increasing amount of energy required to remove the prosthesis from the canal.

Methods

Ten cadaveric radii were implanted with five sizes (6–10 mm in 1-mm increments) of grit-blasted, cementless radial head stems. A customised slap hammer was used to measure the energy required to remove each stem. Stem-bone micromotion was also measured.

Results

The suboptimally sized stem (Max − 1) (i.e. 1 mm undersized) required less energy (0.5 ± 0 J) to pull out than the optimally sized stem (Max) (1.7 ± 0.3 J) (p = 0.008). The optimally sized stem demonstrated greater initial stability (45 ± 7 μm) than the suboptimally sized stem (79 ± 12 μm) (p = 0.004).

Conclusions

This investigation demonstrates the importance of obtaining adequate press-fit stability for the prevention of radial head stem pull-out failure. These data add to the relatively scant knowledge in the literature regarding radial head biomechanics. The energy required to remove a prosthetic radial head ingrowth stem decreases in conjunction with diameter. The use of an inadequately sized stem increases the stem’s micromotion as well as the risk of prosthetic loosening due to pull-out.     

Osseointegration of polyethylene implants coated with titanium and biomimetically or electrochemically deposited hydroxyapatite in a rabbit model

Purpose

The aim of this study was to evaluate the osseointegration of a new coating directly deposited on PE at room temperature.

Methods

Thirty-six (36) male New Zealand rabbits were randomly assigned to receive one out of three types of implants: two tested implants, i.e. PE implant coated with TiPVD and biomimetic HA (biomimetic), PE implant coated with TiPVD and electrolytic HA (electrolytic), and positive control made of massive microrough titanium coated with plasma sprayed HA (TiHAPS). Osseointegration was evaluated by histomorphometry (bone tissue in contact [BIC]), mineralized bone area [MBA]) and mechanical testing (push-out test, interfacial shear strength [ISS]) at six and 12 weeks in the distal femurs.

Results

For BIC there were no differences between the groups at six (p = 0.98) and 12 weeks (p = 0.13). For MBA, no statistically significant difference was measured between groups at six (p = 0.52) and 12 weeks (p = 0.57). At six weeks, interfacial shear strength (ISS) was significantly higher (p = 0.01) for TiHAPs implants compared to biomimetic and electrolytic implants. This difference was not significant at 12 weeks (p = 0.92).

Conclusion

The osseointegration of biomimetic and electrolytic implants was equivalent to a positive control at 12 weeks.     

Proximal femoral nails compared with reverse distal femoral locking plates in intertrochanteric fractures with a compromised lateral wall; a randomised controlled trial

Purpose

There is no consensus about the best option of internal fixation for unstable intertrochanteric fractures. The aim of the present study was to compare proximal femoral nail (PFN) with contralateral reverse distal femoral locking compression plate (reverse-DFLCP) in the management of unstable intertrochanteric fractures with compromised lateral wall.

Method

In a randomized controlled study, from November 2011 to October 2012, 40 patients with unstable intertrochanteric fractures with compromised lateral wall (AO 31A 2.2 to 3.3) had osteosynthesis by PFN (n = 20) or reverse-DFLCP (n = 20). Intra-operative variables compared were duration of surgery, blood loss during surgery, fluoroscopy time and surgeons perception of the surgery. Patients were followed up clinically for a minimum of one year. Functional outcome was assessed by Parker Palmer mobility score (PPMS), Harris hip score (HHS), and Short Form-12. Failure was defined as any condition which would necessitate revision surgery with change of implant.

Results

Duration of surgery (p = 0.022), blood loss during surgery (p = 0.008) and fluoroscopy time (p = 0.0001) were significantly less in the PFN group than in the reverse-DFLCP group. No significant difference was found in type of reduction, difficulty in reduction and surgeon’s perception of surgery. The PFN group had better functional outcome than the reverse-DFLCP group. HHS for the PFN group was 81.53 ± 13.21 and for the reverse-DFLCP group it was 68.43 ± 14.36 (p = 0.018). SF-12 physical (p = 0.002) and mental component (p = 0.007) scores in the PFN group was significantly better than in the reverse-DFLCP group. There was one failure in the PFN group as compared to six in the reverse-DFLCP group (p = 0.036).

Conclusion

Due to favourable intra-operative variables, better functional outcome and lower failure rates, we conclude that PFN is a better implant than reverse-DFLCP for intertrochanteric fractures with compromised lateral wall.Keyword: Unstable intertrochanteric fractures, Lateral wall, Proximal femoral nail, Reverse distal femoral locking compression plate     

Pain reduction following vertebroplasty and kyphoplasty

Purpose

To evaluate the clinical efficacy, especially the pain reduction, of vertebroplasty and balloon kyphoplasty in the treatment of osteoporotic vertebral compression fractures (OVCFs).

Methods

Eighty-six patients with OVCFs were treated with vertebroplasty or balloon kyphoplasty. All patients were followed up for seven–36 months. Visual analog scale (VAS), vertebral height, and local kyphotic angle were evaluated at pre-operation, postoperation, and final follow-up.

Results

The VAS pain score decreased significantly after surgery in both kyphoplasty and vertebroplasty groups (p < 0.001), and the improvement of VAS score had no significant difference between the two groups (p = 0.826). There was a significant difference in the improvement of vertebral height (p < 0.001) and local kyphotic angle (p < 0.001) between the two groups. Improvement of VAS score had no correlation with improvement of vertebral height (vertebroplasty: r = −0.029, p = 0.869; kyphoplasty: r = 0.175, p = 0.219) or local kyphotic angle (vertebroplasty: r = 0.159, p = 0.361; kyphoplasty: r = 0.144, p = 0.312) in either group.

Conclusion

Vertebroplasty and kyphoplasty are effective procedures for the reduction of pain in OVCFs, and they have the same efficient effect on pain reduction. Correction of vertebral height and local kyphosis may have minimal effect on pain reduction.     

Hip resurfacing in patients under thirty years old: an attractive option for young and active patients

Purpose

Metal-on-metal hip resurfacing is offered as an alternative to traditional hip arthroplasty for young, active adults with advanced osteoarthritis. The concept of hip resurfacing is considered very attractive for this specific population (hard-on-hard bearing component with a large femoral head limiting the risk of dislocation, and allowing femoral bone stock preservation).

Methods

A prospective clinical trial was designed to investigate the outcome of hip resurfacing in young patients (under 30 years old). We studied 24 hips in 22 patients. Mean age at operation was 24.9 years (range 17.1–29.9). No patient was lost to follow-up.

Results

There was no revision at average follow-up of 50.6 months (44–59). Mean UCLA activity score improved from 5.5 (1–9) pre-operatively to 7.6 (1–10) postoperatively (p < 0.001). Mean Harris hip score increased from 43.9 (19–67) to 89.3 (55–100) (p < 0.001). Radiological analysis discerned no osteolysis and no implant migration.

Conclusion

The absence of short-term complications, such as mechanical failure or dislocation, is encouraging and leads us to think that mid-term results will be satisfactory. Moreover, the specific advantages of hip resurfacing (bone stock preservation, excellent stability, low risk of dislocation, large-diameter head) make the procedure a very attractive option for young subjects.     

Cationised gelatin and hyaluronic acid coating enhances polyethylene terephthalate artificial ligament graft osseointegration in porcine bone tunnels

Purpose

The aim of this study was to investigate whether cationised gelatin and hyaluronic acid (CH) coating could induce polyethylene terephthalate (PET) artificial ligament graft osseointegration in the bone tunnel.

Methods

Surface modification of PET artificial ligament graft was performed by layer-by-layer (LBL) self-assembly CH coating. Six pigs underwent anterior cruciate ligament (ACL) reconstruction on the right knees, with three pigs receiving the CH-coated PET grafts and the other three pigs non-CH-coated PET grafts as controls. They were sacrificed at three months after surgery and the graft-bone complexes were acquired for computed tomography (CT) scan and histological examination.

Results

CT scans showed a significant difference at the distal femoral site (p = 0.031) or at the distal tibial site (p = 0.0078), but no significant difference in the bone tunnel areas’ enlargement at other sites (p > 0.05) between the CH group and the control group. Histologically, application of CH coating induced new bone formation between graft and bone at three months compared with the controls at the distal site. The interface width of the CH group was significantly lower than that of the control group at the distal femoral site (p = 0.0327) and at the distal tibial site (p = 0.0047).

Conclusions

The study has shown that CH coating on the PET artificial ligament surface has a positive biological effect in the induction of artificial ligament osseointegration within the bone tunnel at the distal site of the bone tunnel.     

Vascularised greater trochanter bone graft, combined free iliac flap and impaction bone grafting for osteonecrosis of the femoral head

Purpose

To investigate the curative efficacy of osteonecrosis of the femoral head (ONFH) in a hip-preserving operative approach, by grafting a vascularized greater trochanter flap combined with a free iliac flap, in an attempt to seek an innovative approach for patients who suffered middle to late stage ONFH without total hip arthroplasty (THA) surgery.

Method

Our research included a total of 60 patients (66 hips) who accepted hip-preserving surgery by grafting a vascularized greater trochanter flap combined with a free iliac flap which was tightly filled by hammering because of ONFH (most were Association Research Circulation Osseous (ARCO) stage III patients) from January, 2006 to December, 2010. A Harris Hip Score was obtained during follow-ups, evaluating the clinical efficacy, X-rays were taken regularly for image assessing, and the SF-36 scale was used for estimating quality of life. Terminal observation time was considered when patients had symptom-dependant indications for performing another hip-preserving surgery or THA surgery.

Results

Fifty-eight patients (64 hips) were eventually contacted by telephone for an out-patient clinic return visit, with a mean follow-up time of 35.8 months (varied from 12 months to 60 months), but two patients lost contact for various reasons. The demographic data were as follows: there were 16 ARCO IIIA cases, 22 ARCO IIIB cases, and 26 ARCO IIIC cases, respectively. Postoperative X-rays revealed a well-repaired necrotic area of the femoral head and improvement of femoral-acetabulum coverage. The last follow-up mean Harris Hip Score was 86.56 ± 7.38 (excellent results reached 87.50 %), which were greatly improved compared to 50.95 ± 6.86 pre-operatively. Also the postoperative mean scores of all dimensions of the SF-36 scale were improved to some extent. Additionally the physical component summary (PSC) scores were enhanced from 42 ± 13 pre-operatively to 78 ± 11, while the postoperative mental component summary (MCS) scores (76 ± 11) largely increased in contrast to pre-operative scores (51 ± 10), with both target indices having statistical significance (p = 0.005, p = 0.01), signifying hugely improvement of the quality of life of the patients. A correlation was found between Harris Hip Score and all dimensions of SF-36 scale (r = 0.32–0.72), especially closely correlated with physical functioning (PF), role-physical (RP) and bodily pain (BP) in PCS aspect (r = 0.72, p < 0.01; r = 0.58, p < 0.01; r = 0.65, p < 0.01, respectively).

Conclusion

There is definite curative efficacy for the treatment of ONFH with an hip-preserving operative approach by grafting a vascularized greater trochanter flap combined with a free iliac flap which was tightly filled by hammering. This kind of operative approach reconstructs the biological stability of femoral head, which promotes repair of necrotic areas and indirectly preserves the femoral head of patients and a majority of hip function. It possesses vast clinical as well as practical significance, because the long-term efficacy can satisfy fundamental life requirements, especially for those young and middle-aged patients who suffer ONFH to avoid or put off the time of total hip arthroplasty(THA) surgery.     

A radiographic and clinical comparison of reamer–irrigator–aspirator versus iliac crest bone graft in ankle arthrodesis

Purpose

We evaluated radiographic fusion at follow-up and complication rates in patients who had either iliac crest (ICBG) or femoral reamer–irrigator–aspirator (RIA) bone graft for tibiotalar fusion.

Methods

We retrospectively reviewed charts and radiographs of all patients who had a tibiotalar fusion from August 2007 to February 2011. Records were analysed for patient demographics, complications, and clinical symptoms. Radiographs were reviewed in sequential order by two fellowship-trained foot and ankle surgeons and one orthopaedic surgeon who specialises in foot and ankle surgery to determine radiographic fusion at routine follow-up. Patients were contacted to determine current visual analog scores (VAS) at their graft site.

Results

Mean patient age was 49.4 ± 12.1 years in the RIA group and 49.3 ± 15.4 years in the ICBG group (p = .97). Pre-operative characteristics showed no significant differences between groups. The ICBG group had significantly more nonunions than the RIA group (six vs. one, p = 0.04). Two patients in the ICBG had chronic pain at their graft site based on their VAS score; there were none in the RIA group. Radiographic fusion at follow-up was similar between groups, with no significant difference (12.48 ± 3.85 weeks vs.12.21 ± 3.19 weeks, p = .80).

Conclusions

There was a significantly higher nonunion rate in the ICBG group, but both groups had a solid radiographic bony fusion at similar follow-up time points. Our results suggest RIA bone graft is a viable alternative to ICBG for tibiotalar fusion.     

Comparison of low, multidirectional locked nailing and plating in the treatment of distal tibial metadiaphyseal fractures

Purpose

The aim of this study was to compare the results of a new technique for low, multidirectional locked nailing with closed reduction and minimally invasive plating in the treatment of distal tibial metadiaphyseal fractures.

Methods

Forty-six matched patients were divided according to age, gender, Injury Severity Score, and fracture pattern into group A (expert tibial nailing) and group B (minimally invasive plating). Then, the patients were followed up, and the clinical and radiographic results were retrospectively analysed.

Results

The mean followed-up was 24.7 ± 2.7 months in group A and 25.8 ± 2.8 months in group B. No patient had nonunion, shortening, hardware breakdown, or deep-seated infection. Patients in group A had a significantly shorter mean operating time, hospital stay, full weight-bearing time and union time (76 ± 16.6 vs. 90 ± 20.3 minutes, p = 0.000; 5.8 ± 2.1 vs. 8.9 ± 3.1 days, p = 0.000; 9.0 ± 1.4 vs. 11.1 ± 1.7 weeks, p = 0.000; and 21.3 ± 3.5 vs. 23.1 ± 3.6 weeks, p = 0.047, respectively). Three patients in group A and one patient in group B presented with malalignment (p = 0.608). The mean Olerud-Molander Ankle score was 89.0 ± 7.1 in group A and 87.6 ± 8.4 in group B (p = 0.478).

Conclusions

Distal tibia metadiaphyseal fractures may be treated successfully with low, multidirectional locked nails or plates. However, low, multidirectional locked nailing may represent a superior surgical option, since it offers advantages in terms of mean operating time, hospital stay, full weight-bearing time and union time.     

The influence of patella height on soft tissue balance in cruciate-retaining and posterior-stabilised total knee arthroplasty

Purpose

Although the patella reduced or everted position has recently been recognised as an important factor influencing soft tissue balance during assessment in total knee arthroplasty (TKA), the influence of patella height on soft tissue balance has not been well addressed. Therefore, the relationship between soft tissue balance and patella height was investigated and differences between cruciate-retaining (CR) and posterior-stabilised (PS) TKA were compared.

Methods

Forty consecutive patients blinded to the type of implant received, were randomised prospectively. Using lateral radiographs, pre-operative patella height was measured. Using an offset-type tensor designed to measure the soft tissue balance with a reduced patellofemoral (PF) joint and femoral component in place, soft tissue balance was intra-operatively assessed in CR TKA (n = 20) and PS TKA (n = 20) in osteoarthritic patients. The joint component gap and varus ligament balance at zero, ten, 45, 90 and 135° of knee flexion with the patella reduced were measured.

Results

In PS TKA, the joint component gap positively correlated with patella height at 90 and 135° of knee flexion. However, there was no correlation between joint component gap and patella height at other flexion angles in PS TKA and any flexion angle in CR TKA. Varus ligament balance showed no significant correlation with patella height in either CR or PS TKA.

Conclusion

Analysis of soft tissue balance and patella height only showed a positive correlation in joint component gap at a high flexion angle (90 and 135°) in PS TKA but not in other parameters examined. Pre-operative measurement of patella height may be an important factor for predicting an intra-operative flexion gap in PS TKA.     

The First SICOT Oral Presentation Award 2011: Imageless computer-assisted femoral component positioning in hip resurfacing: a prospective randomised trial

Purpose

The aim of the study was to evaluate the effects of imageless computer-assisted surgery (CAS) on the accuracy of positioning of the femoral component and on the short-term clinical outcome in hip resurfacing (HR) using a randomised prospective design.

Methods

A total of 75 consecutive patients undergoing HR were randomly allocated to CAS and conventional implantation, respectively. Preoperatively and six months post-operatively standardised pelvic anteroposterior X-ray images, the total Western Ontario and McMaster Universities Osteoarthritis Index, the Harris Hip Score and the EQ-5D utility index were evaluated in a blinded manner. The primary end point of the study was a post-operative femoral component malpositioning in five degrees or more either varus or valgus absolute deviation from the planned stem shaft angle.

Results

Patient demographics and algofunctional scores did not differ between the CAS and conventional implantation samples. Using CAS fewer femoral components were positioned in five or more degrees absolute deviation (4/37 vs 12/38, Fisher’s exact p = 0.047; 95 % confidence interval for the primary end point’s incidence difference: +3 %; +39 %); the respective incidences of five or more degrees of varus deviation were 0/37 vs 5/38. One conversion to a stemmed prosthesis (CAS group) was performed for periprosthetic femoral neck fracture. Radiological signs of superolateral femoral neck/implant impingement were observed in two cases (one CAS-based and one conventional implantation).

Conclusions

The accuracy of femoral HR component positioning was significantly improved using CAS. However, one major complication necessitated early revision in the CAS group at six months of observation. Apart from that adverse event no inter-group differences were observed for the short-term clinical outcome. Future studies need to address the clinical long-term relevance of CAS in HR.     

The locking attachment plate for proximal fixation of periprosthetic femur fractures-a biomechanical comparison of two techniques

Purpose

Mechanical properties of a locking attachment plate construct (LAP-LCP), allowing bicortical screw placement laterally to the prosthesis stem, are compared to a cerclage-LCP construct.

Methods

Eight right synthetic femora with implanted uncemented hip endoprosthesis were cut distally and fixed with LCP, monocortical locking screws and either LAP (n = 4) or cerclage (n = 4). Cyclic testing was performed with monotonically increasing sinusoidal load until failure. Relative movements at the plate–femur interface were registered by motion tracking. Statistical differences were detected by unpaired t-test and general linear model repeated measures.

Results

Stiffness of the LAP-LCP was significantly higher at the beginning (875.4 N/mm ± 29.8) and after 5000 cycles (1213.0 N/mm ± 101.1) compared to the cerclage-LCP (644.96 N/mm ± 50.1 and 851.9 N/mm ± 81.9), with p = 0.013. Relative movements for AP-bending (B) and axial translation (T) of the LAP-LCP at the beginning (0.07° ± 0.02, 0.20 mm ± 0.08), after 500 cycles (0.16° ± 0.10, 0.26 mm ± 0.07) and after 5000 cycles (0.26° ± 0.11, 0.31 mm ± 0.07) differed significantly from the cerclage-LCP (beg.: 0.26° ± 0.04, 0.28 mm ± 0.05; 500 cyc: 0.47° ± 0.03, 0.53 mm ± 0.07; 5000 cyc.: 0.63° ± 0.18, 0.79 mm ± 0.13), with B: p = 0.02, T: p = 0.04. Relative movements for medial bending were not significantly different between the two constructs. Cycles to failure (criterion 1 mm axial translation) differed significantly between LAP-LCP (19,519 ± 1,758) and cerclage-LCP (11,265 ± 2,472), with p = 0.035.

Conclusions

Biomechanically, the LAP-LCP construct improves proximal fixation of periprosthetic fractures compared to the cerclage-LCP construct.