Reproducibility of digital measurements of lower-limb deformity on plain radiographs and agreement with CT measurements

INTRODUCTION

Five angles (HKA, HKS, alpha, beta, tibial slope) are used for goniometry in total knee arthroplasty. The reproducibility of the measurement of these angles has been assessed on plain and digitized x-rays, but to our knowledge, this has not been confirmed on x-rays taken on the PACS system and they have not been compared to computed tomography (CT) measurements, the reference for angle measurement. This prospective study aimed to: (1) evaluate the inter- and intrarater reliability of the measurement of these angles on digital x-rays taken on a PACS; (2) determine the agreement of these measurements with those obtained using a CT protocol.

HYPOTHESIS

The measurements of these five angles on digitized radiographs are reproducible and in agreement with CT values.

MATERIAL AND METHODS

Forty-two patients suffering from knee osteoarthritis and scheduled for total knee arthroplasty were included in the study. Each patient had a PACS digitized x-ray and a CT intended to produce patient-specific instrumentation (Symbios, Yverdon, Switzerland) including measurements of the angles evaluated. Four senior orthopaedic surgeon-raters measured all the angles twice. Inter- and intrarater reliability was then calculated as well as the agreement between the second measurement of each rater and the CT measurement using interclass correlation and kappa coefficients (data provided as means and 95% confidence intervals).

RESULTS

The inter- and intrarater reliability values were excellent for the HKA, alpha, and beta angles (with, respectively, a coefficient of 0.99 [0.97-0.99], 0.84 [0.76-0.9], and 0.94 [0.86-0.96] interrater reliability and 0.98 [0.96-0.99], 0.86 [0.75-0.92], and 0.65 [0.44-0.8] intrarater reliability). Interrater reliability was low for HKS and tibial slope angles (coefficients all<0.4 for interrater reliability and <0.7 for intrarater reliability). The x-ray/CT agreement was very good for the HKA, alpha, and beta angles (0.81 [0.67-0.99], 0.74 [0.56-0.91], and 0.74 [0.45-0.92], respectively) and low for the HKS and tibial slope angles (all<0.45).

DISCUSSION/CONCLUSION

The HKA, alpha, and beta angles were reproducible for digital radiographs and showed good agreement with CT measurements. HKS and tibial slope angles should be used with greater caution, and other navigation methods or patient-specific instrumentation should be explored.

LEVEL OF EVIDENCE

Level III, prospective, comparative diagnostic case-control study.

Total knee arthroplasty revision with trabecular tantalum cones: Preliminary retrospective study of 51 patients from two centres with a minimal 2-year follow-up

BACKGROUND

Successful management of large bone defects is of crucial importance when performing revision total knee arthroplasty (TKA). Trabecular tantalum cones may improve prosthesis fixation via their potential for reconstructing a stable metaphyseal support. The objective of this study was to evaluate the clinical and radiological outcomes and the complications of tantalum cones in revision TKA.

HYPOTHESIS

Trabecular tantalum cones provide stable and durable metaphyseal reconstruction when used during revision TKA.

MATERIAL AND METHODS

Trabecular Metal™ cones (Zimmer, Warsaw, IN, USA) were used for 52 revision TKAs in 51 patients (mean age, 68±9 years) managed in two centres between 2008 and 2013. A rotating hinge prosthesis was chosen for 38 (73%) knees and a condylar constrained knee prosthesis for 14 (27%) knees, with 37 tibial and 34 femoral cones. The two most common reasons for revision surgery were aseptic loosening (n=22, 42%) and infection (n=19, 37%). The bone loss was severe in most cases. At each centre, after a mean follow-up of 34 months (range, 24-52 months), two independent observers assessed the Knee Society Score (KSS), range of motion, mechanical axis, and osteo-integration for each patient.

RESULTS

Mean KSS increased from 46 preoperatively to 77 (P=0.001) at last follow-up and the mean KSS function from 39 to 57 (P=0.007). Mean range of motion improved from 93° (45°-120°) to 110° (65°-130°) (P=0.001). Mean postoperative mechanical axis was 180° (172°-190°). Radiographic evaluation showed evidence of osteo-integration for all cones. Four revisions were performed for recurrence of infection but none for mechanical failure.

DISCUSSION

The findings of our study confirm the biomechanical and biological reliability of Trabecular Metal™ cones used to fill metaphyseal bone defects during revision TKA.

LEVEL OF EVIDENCE

IV, retrospective therapeutic study.

Technique to treat iliopsoas irritation after total hip replacement: Thickening of articular hip capsule through an abridged direct anterior approach

Iliopsoas irritation due to acetabular cup component impingement following total hip arthroplasty (THA) is usually treated by infiltration or by distal iliopsoas tenotomy in case of recurrence; however, this can result in an active flexion deficit of the thigh. To prevent this complication, we developed an original technique that we performed between 2012 and 2014 in patients with recurrent impingement following extraarticular corticosteroid injections. This included 5 patients (mean age: 64 [53-75] years old) in whom we performed an ambulatory bursectomy by the Hueter approach and placed a polyglactin 910 (Vicryl™) mesh plate on the entire anterior hip capsule. After a mean follow-up of 12months (9-29months), anterior pain had decreased in all patients with improvement and an increase in the Oxford-12 (mean: 15 points [10-19]), Merle d'Aubigné (mean: 2.5 points [1-5]) and Harris (mean: 18 points [10-29]) scores. No flexion deficits were observed. An infected postoperative hematoma had to be drained but was cured at follow-up. This simple procedure provides satisfactory results and preserves THA function. It does not jeopardize future procedures and is an alternative option in case of unsuccessful conservative treatment.

Does severity of femoral trochlear dysplasia affect outcome in patellofemoral instability treated by medial patellofemoral ligament reconstruction and anterior tibial tuberosity transfer?

INTRODUCTION

Medial patellofemoral ligament (MPFL) reconstruction associated to anterior tibial tuberosity transfer (ATTT) is recommended in objective patellofemoral instability (PFI). Efficacy, however, has not been precisely determined in trochlear dysplasia with spur. A case-control study was performed in a PFI population, comparing groups with trochlear dysplasia with and without spur (S+ vs. S-) to assess the impact of trochlear dysplasia on (1) patellofemoral stability, (2) functional results and complications, and (3) patellofemoral cartilage status on MRI.

HYPOTHESIS

Trochlear spur does not affect outcome in PFI managed by MPFL reconstruction and ATTT.

MATERIAL AND METHODS

Twenty-eight knees (26 patients) with PFI were analyzed retrospectively and divided into 2 groups of 14 knees each according to presence of trochlear spur (S+ vs. S-). All 28 knees had undergone ATTT and MPFL reconstruction by semitendinosus autograft. Results were assessed on Lille and IKDC functional scores, and cartilage status was determined on MRI at last follow-up.

RESULTS

At a mean 24 months' follow-up (range, 12-52 months), there was no recurrence of dislocation. IKDC and Lille scores tended to improve in both groups, although the only significant improvement was in IKDC score (S- gain, 21.3±16; S+ gain, 18.1±14) (P=0.01). IKDC scores at last follow-up were better in the S+ than S- group (79±19 [range, 21-92] vs. 68±13 [range, 35-84], respectively; P=0.012). Lille scores showed no significant inter-group differences in mean gain (P=0.492) or mean value (P=0.381). The S+ group showed more cartilage lesions (n=14/14 knees, including 12/14 with grade≥2 lesions) than the S- group (n=9/14 knees, all grade≤2).

CONCLUSION

MPFL reconstruction with ATTT provided good short-term patellofemoral stability independently of the severity of trochlear dysplasia. Functional results and gain on IKDC, however, were poorer in case of dysplasia with trochlear spur. This is probably due to cartilage lesions, observed more frequently pre- and post-operatively in the spur group, especially as there was no significant difference in Lille Score, which highlights stability.

LEVEL OF EVIDENCE

III, retrospective case-control study.

Computed tomography evaluation of hip geometry restoration after total hip resurfacing

BACKGROUND

Anatomic reconstruction of the hip is among the main requirements for hip arthroplasty to be successful. Resurfacing arthroplasty may improve replication of the native joint geometry but has been evaluated only using standard radiographs. We therefore performed a computed tomography (CT) study to assess restoration of hip geometry after total hip resurfacing (HR), comparatively with the non-operated side.

HYPOTHESIS

HR does not change native extra-medullary hip geometry by more than 5mm and/or 5°.

PATIENTS AND METHODS

CT was used to evaluate unilateral HR in 75 patients with a mean age of 52.2years (range, 22-67years). The normal non-operated side served as the control in each patient. Mean follow-up was 2.5years (range, 1.9-3.1years). The primary evaluation criteria were femoral offset (FO) and femoral neck anteversion (FNA) and the secondary criteria were cup inclination angle, cup anteversion angle, and lower-limb length.

RESULTS

FO showed a non-significant decrease (mean, -2.2mm; range, -4.5 to +3.7mm). FNA was preserved, with a difference of less than 2° at last follow-up versus the preoperative value. Cup measurements showed a mean anteversion angle of 24.8° (0.9-48.6) and mean inclination angle of 44.1° (32.1-56.3); corresponding values for the native acetabulum were 38.9° (20.5-54.8) and 24.8° (4.8-33.6). The residual lower-limb length discrepancy was less than 1mm (mean, -0.04mm [-1.2 to +1.6mm]). The mean angle between the femoral implant and the femoral neck axis was 5.4° of valgus.

DISCUSSION

Our results show that HR accurately restored the native extra-medullary hip geometry.

LEVEL OF EVIDENCE

III, prospective diagnostic case-control study.

Sulcus deepening trochleoplasty for patellofemoral instability: A series of 34 cases after 15 years postoperative follow-up

INTRODUCTION

Trochlear dysplasia is one of the main elements of patellofemoral instability. Although correction by trochleoplasty seems logical, the long-term outcome of this procedure is unknown and the progression to osteoarthritis has not been clarified. Thus, we performed a retrospective study of a series of sulcus deepening trochleoplasties with a 15-year follow-up whose goal was to (1) evaluate the long-term clinical outcome and radiological rate of osteoarthritis, and (2) define the results in relation to the type of instability and the grade of dysplasia.

HYPOTHESIS

Sulcus deepening trochleoplasty is an effective procedure to stabilize the patellofemoral joint that does not increase the risk of osteoarthritis.

PATIENTS AND METHODS

This retrospective study analyzed 34 sulcus deepening trochleoplasties based on clinical scores (IKS, Lille, Kujala and Oxford scores) and radiological results (stage of osteoarthritis according to the Iwano score) after a mean follow-up of 15 years (12-19 years). An Insall procedure was systematically associated with an anterior tibial tubercle transfer in 17 cases (7 prior tibial transfers).

RESULTS

No recurrent objective instability was observed. Seven knees had additional surgery after a mean follow-up of 7 years (2-16): 7 underwent conversion to total knee arthroplasty because of progression of osteoarthritis and one knee had tibial tubercle transfer for pain and episodes of the knee giving way. The mean Lille, Kujala and IKS scores increased from 53.3 (30-92), 55 (13-75) and 127 (54-184) to 61.5 (25-93), 76 (51-94) and 152.4 (66-200) respectively between preoperative and follow-up assessment (P<0.05) (revisions included). Functional outcome was significantly better for dysplasia with supratrochlear spurs (IKS score 168 [127-200] versus 153 [98-198] and Kujula score 81.5 [51-98] versus 76 [51-94] [P<0.05]). Patients were satisfied in 65% of the cases and the total mean Oxford score was 24.1/60 (12-45 points). Occasional pain was present in 53% of the cases. The trochlear prominence decreased from 4.9 mm (3-9 mm) to -1.2mm (-7-4mm). Ten cases of preoperative patellofemoral osteoarthritis were identified, but none with>Iwano 2, while osteoarthritis was present in 33/34 cases at the final follow-up with 20 cases>Iwano 2 (65%).

DISCUSSION

Sulcus deepening trochleoplasty corrects patellofemoral stability even in patients with severe dysplasia and the long-term functional outcome is better in this group. It does not prevent patellofemoral osteoarthritis. It should be limited to severe dysplasia with supratrochlear spurs and associated with procedures to realign the extensor apparatus.

Long-term outcomes of primary constrained condylar knee arthroplasty

BACKGROUND

Although constrained condylar knee (CCK) inserts are widely used for total knee arthroplasty (TKA), their long-term outcomes remain unclear. We sought to evaluate patients with at least 10 years' follow-up after CCK TKA to identify potential adverse events (osteolysis, loosening, constraint-mechanism failure), assess functional outcomes with special emphasis on range of motion, and determine prosthesis survival.

HYPOTHESIS

Increasing constraint by implantation of a CCK insert does not increase the long-term frequencies of osteolysis or mechanical loosening.

MATERIAL AND METHODS

We studied 43 knees after Legacy(®) CCK TKA. The indication was severe deformity (n=20), pre-operative laxity (n=6), or failure to achieve intra-operative balancing (n=17). There were 41 patients with a mean age of 66 years (21-88). A history of one or more surgical procedures was noted for 27 (63%) knees. Outcome measures were the Hospital for Special Surgery (HSS) knee score, Knee Society Score (KSS), and change in the hip-knee-ankle (HKA) angle. Prosthesis survival was assessed using revision surgery for any reason or for reasons other than infection as the censoring criterion.

RESULTS

Complications other than venous thrombosis occurred in 16% of patients, including 3 who required revision surgery (septic loosening, n=2; and major instability in a patient with ipsilateral hip arthrodesis). No cases of osteolysis or aseptic loosening were recorded. Mean follow-up was 12.7 years (range, 10-14). At last follow-up, the HSS score had improved from 53 (26-83) pre-operatively to 80 (55-93), the KSS knee component from 42 (16-77) to 90 (77-99), and the KSS function component from 31 (0-80) to 61 (10-90) (P<0.001). Mean range of flexion increased from 109° (50°-140°) to 112° (90°-130°) (P=0.12). The HKA angle changed from 182°±15.5° (150°-210°) to 179.5°±2.5° (174°-184°) (P=0.5). The 11-year prosthesis survival rate was 88.5% (95% confidence interval, 0.69-0.94) overall and 97.7% (0.76-0.99) after excluding the cases of infection.

DISCUSSION

Long-term functional gains after CCK TKA were similar to those reported after standard posterior-stabilised TKA, with no cases of constraint-mechanism failure or osteolysis. The complication rate was higher, with decreased survival compared to standard TKA, but the knee deformities and/or instability were particularly severe and two-thirds of knees had a history of one or more surgical procedures.

Tantalum cones and bone defects in revision total knee arthroplasty

Management of bone loss is a major challenge in revision total knee arthroplasty (TKA). The development of preformed porous tantalum cones offers new possibilities, because they seem to have biological and mechanical qualities that facilitate osseointegration. Compared to the original procedure, when metaphyseal bone defects are too severe, a single tantalum cone may not be enough and we have developed a technique that could extend the indications for this cone in these cases. We used 2 cones to fill femoral bone defects in 7 patients. There were no complications due to wear of the tantalum cones. Radiological follow-up did show any migration or loosening. The short-term results confirm the interest of porous tantalum cones and suggest that they can be an alternative to allografts or megaprostheses in case of massive bone defects.

Femoral lengthening during hip resurfacing arthroplasty: a new surgical procedure

Correction of leg length discrepancy during hip arthroplasty is a technical challenge. Although resurfacing proposed to young subjects presents a number of advantages (stability, bone stock, etc.), it does not correct leg length discrepancy. We propose an original femoral lengthening technique concomitant to resurfacing performed through the same approach, consisting in a Z-shaped subtrochanteric osteotomy. Resurfacing was performed first and the femoral and acetabular reaming material was used for autografting. The series comprised five cases followed for a mean 42.2 months (range, 33-64 months). The mean surgical time was 100 min (range, 76-124 min). Weightbearing was authorized in all cases at the 8th week. The mean lengthening was 32 mm (range, 25-40 mm). Healing was observed in all cases. This surgical technique, reserved for very young subjects who accept an 8-week postoperative period without weightbearing, can be proposed in cases with substantial preoperative leg length discrepancy.

Does prior conservative surgery affect survivorship and functional outcome in total hip arthroplasty for congenital dislocation of the hip? A case-control study in 159 hips

INTRODUCTION

The results of total hip arthroplasty (THA) in congenital dislocation of the hip (CDH) are well known, but such is not the case for the impact of prior conservative surgery on THA function and survivorship. The present study compared THA in CDH with prior conservative bone surgery (BS group) versus no prior bone surgery (NBS group), to (1) assess the impact of prior conservative surgery on function and survivorship after THA, and (2) determine whether a particular type of conservative surgery affected function or survivorship.

HYPOTHESIS

Prior conservative surgery for CDH does not affect function or survivorship of subsequent THA.

PATIENTS AND METHODS

A multicenter retrospective case-control study analyzed 430 THAs in CDH patients (332 patients: 269 female, 63 male; mean age, 56 years [range, 17-80 years]) at a mean 13.2±5.4 years' follow-up (range, 1-29 years). The BS group included 159 hips (37%) (64 pelvic, 81 femoral and 14 combined pelvic and femoral osteotomies), and the NBS group 271 (63%). Groups were comparable for gender, age at surgery, Devane activity score, preoperative Postel Merle d'Aubigné (PMA) functional score and CDH radiographic type following Crowe.

RESULTS

At follow-up, PMA scores were comparable: BS, 16.8±1.4 (11-18); NBS, 16.9±1.5 (7-18). Fifteen-year survivorship censored for implant revision for whatever reason did not significantly differ: BS, 87% (95% CI: 83-91%); NBS, 89% (95% CI: 86-92%). Ten-year survivorship on the same criterion did not significantly differ according to type of prior surgery: hip shelf arthroplasty, 97% (95% CI: 95-99%); Chiari osteotomy, 100%; femoral osteotomy, 95% (95% CI: 92-98%); and Milch osteotomy 96% (95% CI: 93-99%).

DISCUSSION/CONCLUSION

Conservative surgery for CDH does not impair the functional results or survivorship of subsequent THA.

LEVEL OF EVIDENCE

III, case-control study.

Potential changes to French recommendations about peri-prosthetic infections based on the international consensus meeting (ICMPJI)

BACKGROUND

Despite the large volume of studies on the prevention, diagnosis, and treatment of peri-prosthetic infections, surgical practice often rests on limited scientific evidence in this field. The vast International Consensus Meeting on Peri-prosthetic Joint Infection (ICMPJI) held in 2013 produced robust recommendations.

HYPOTHESIS

French consensus conference recommendations show no major differences with ICMPJI recommendations.

MATERIALS AND METHODS

The 207 recommendations developed by 300 experts at the ICMPJI were translated, and the translation was then examined by four reviewers, including 2 having participated in the consensus conference. The reviewers looked for any differences with French practices and recommendations.

RESULTS

Twenty-three major differences or innovations were identified compared to French recommendations and standard practice. Among them, pre-operative screening for nasal or urinary micro-organisms is performed routinely in France but should be reserved according to the ICMPJI for symptomatic patients and/or patients at high risk for infection. The ICMPJI emphasizes the role for the operating room environment as a vector for infection; more specifically, the operating lamp handle and suction cannula deserve close attention. A wound discharge persisting longer than 5-7 days requires irrigation and debridement. This procedure is effective only within the first 3 post-operative months and/or the first 3 weeks after symptom onset and must include exchange of all modular implants. The ICMPJI warns against both irrigation-debridement in fungal infections (suggesting two-stage prosthesis replacement) and one-stage replacement in patients with sinus tracts. The use of spacers (articulating at the knee) is recommended in the event of two-stage prosthesis replacement.

DISCUSSION

The ICMPJI recommendations differed in many ways with French recommendations and standard practice. They can be expected to impact practices in France, although a point worth noting is that only 1 of the 207 recommendations received unanimous agreement by the conference experts (keeping operating room traffic to a minimum).

Surface feeding and aggressive behaviour of diploid and triploid brown trout Salmo trutta during allopatric pair-wise matchings

Diploid and triploid brown trout Salmo trutta were acclimated for 6 weeks on two feeding regimes (floating and sinking). Thereafter, aggression and surface feeding response were compared between pairs of all diploid, all triploid and diploid and triploid S. trutta in an experimental stream. In each pair-wise matching, fish of similar size were placed in allopatry and rank was determined by the total number of aggressive interactions recorded. Dominant individuals initiated more aggression than subordinates, spent more time defending a territory and positioned themselves closer to the surface food source (Gammarus pulex), whereas subordinates occupied the peripheries. In cross ploidy trials, diploid S. trutta were more aggressive than triploid, and dominated their sibling when placed in pair-wise matchings. Surface feeding, however, did not differ statistically between ploidy irrespective of feeding regime. Triploids adopted a sneak feeding strategy while diploids expended more time defending a territory. In addition, we also tested whether triploids exhibit a similar social dominance to diploids when placed in allopatry. Although aggression was lower in triploid pairs than in the diploid and triploid pairs, a dominance hierarchy was also observed between individuals of the same ploidy. Dominant triploid fish were more aggressive and consumed more feed items than subordinate individuals. Subordinate fish displayed a darker colour index than dominant fish suggesting increased stress levels. Dominant triploid fish, however, appeared to be more tolerant of subordinate individuals and did not display the same degree of invasive aggression as seen in the diploid and diploid or diploid and triploid matchings. These novel findings suggest that sterile triploid S. trutta feed similarly but are less aggressive than diploid trout. Future studies should determine the habitat choice of triploid S. trutta after release and the interaction between wild fish and triploids during the breeding season prior to utilization of triploids as an alternative management strategy within freshwater fisheries.

The ilio-inguinal approach for recent acetabular fractures: ultrasound evaluation of the ilio-psoas muscle and complications in 24 consecutive patients

INTRODUCTION

The ilio-inguinal approach is used to achieve internal fixation of acetabular fractures. Although the outcomes of this procedure have been extensively reported, information is lacking on potential complications. More specifically, the effect on the ilio-psoas muscle, whose iliac attachments are almost completely released, has not been accurately evaluated.

HYPOTHESIS

Endopelvic dissection does not alter the ultrasound structure of the ilio-psoas muscle compared to the normal side at a distance from acetabular internal fixation via the ilio-inguinal approach.

PATIENTS AND METHODS

We retrospectively evaluated 26 patients who underwent internal fixation of acetabular fractures via the ilio-inguinal approach between 2006 and 2010. Two patients with multiple injuries died shortly after the procedure, leaving 24 patients with unilateral fractures for the study. In 2012, an observer who was not involved in the surgical treatment of these patients conducted an assessment (Oxford score except in the 8 patients who required revision surgery for arthroplasty and evaluation for a deficit of the lateral femoral cutaneous nerve in the full cohort). At the same time point, ultrasonography was performed to compare ilio-psoas muscle morphology on the two sides. Any other complications (vascular, nervous, or parietal) were recorded.

RESULTS

Of the 24 patients, 11 (45%) experienced complications, of whom only 3 required further surgery, 2 with infections that recovered fully after lavage and 1 with a haematoma responsible for compression of the urinary bladder. The lateral femoral cutaneous nerve was injured in 8 (33%) patients, including 4 who had achieved a full recovery at last follow-up. At last follow-up, none of the 24 patients had ultrasound evidence of a significant difference in ilio-psoas muscle size at the lateral window: mean transverse diameter was 51.8±0.8mm (range, 44-58 mm) on the operated side versus 51.7±0.79 mm (range, 44-59 mm) on the other side (P=0.9). After a mean follow-up of 49 months (range, 31-70 months), the mean Oxford score in the 16 patients who had not required further surgery was 20.5/60 (range, 12-44).

DISCUSSION

Our results show that, despite extensive endopelvic dissection, the ilio-inguinal approach has no effect on the ultrasound morphology of the ilio-psoas muscle. There is a high risk of injury to the lateral femoral cutaneous nerve that should be disclosed to the patient before the procedure. In contrast, no parietal complications were recorded. In selected patients, the Cole-Stoppa approach is an alternative that spares the lateral femoral cutaneous nerve.

LEVEL OF EVIDENCE

Level IV, retrospective study.

Is cemented metal-polyethylene 22.2mm hip arthroplasty a gold standard? Results of a series of 105 primary arthroplasties at a minimum of ten years follow-up

INTRODUCTION

Although Charnley-Kerboull metal-on-polyethylene 22.2mm cemented total hip arthroplasty (THA) is considered to be the gold standard in France, results with this prosthesis are conflicting, in particular in relation to Scandinavian registers. The goal of this retrospective study was to confirm the validity of this prosthesis at a minimum of 10years follow-up.

HYPOTHESIS

Survival of this type of THA would fulfill NICE conditions (survival at 10 years of at least 90%).

MATERIALS AND METHODS

One hundred and five primary THA were performed in 93 patients (30 men and 63 women) mean age 72.6 years old (60-86) between January 1998 and March 2001. After a mean follow-up of 10.6 years (10-13 years), 21 patients (23 THA) were lost to follow-up and 32 (35 THA) had died leaving 40 patients (47 THA) for clinical analysis (Merle d'Aubigné and Oxford scores) and X-ray assessment. Survival was calculated with revision for any cause and radiological loosening with or without revision as end-points.

RESULTS

The mean Oxford score at the final follow-up was 22/60 (13-45), the PMA score was 14.2 (11-17). Eight patients underwent revision surgery after a mean 7.5 years (2-11) (1 early dislocation and 7 acetabular cup loosenings). Survival at 10 years was 89.4% (CI95%: 78-95) for all causes of revision and 78% (CI95%: 61-91) for loosening with (n=7) or without (n=3) revision. No cases of septic or femoral loosening were observed. Twelve of the 47 revised hip replacements (25.5%) presented wear≥2mm.

DISCUSSION

Although functional results were acceptable for this elderly population, survival did not reach the NICE value and was lower than results in the literature for this type of implant. Cup loosening and wear were the main causes of revision.

LEVEL OF EVIDENCE IV

retrospective.

Triploid and diploid Atlantic salmon show similar susceptibility to infection with salmon lice Lepeophtheirus salmonis

BACKGROUND

Sea lice infection is the most expensive disease factor for Atlantic salmon sea-cage farming. For triploid salmon to be accepted as a commercial possibility, investigation of susceptibility of triploid salmon to sea lice infection is a fundamental milestone. The susceptibility of diploid and triploid salmon to infection with Lepeophtheirus salmonis was examined in a tank trial in Scotland, a tank trial in Norway and a cage trial in Scotland.

RESULTS

Following a single infection challenge, results indicated a significant correlation between fish size and the number of attached sea lice. Triploid fish were larger than diploids at the smolt stage. In the tank trials, no difference was found between infection levels on diploids and triploids after a single infection challenge. The tank trial in Scotland continued with a second infection challenge of the same fish, which also showed no infection differences between ploidies. A borderline correlation between first infection and re-infection intensity was found for PIT-tagged diploid salmon examined after each challenge. No significant difference in louse infection between diploid and triploid salmon (∼2 kg) was found in the cage trial undertaken under commercial conditions.

CONCLUSION

This study concludes that triploid Atlantic salmon are not more susceptible to sea louse infection than diploid fish.

Gender distribution, sexual size dimorphism and morphometric sexing in ballan wrasse Labrus bergylta

In wild ballan wrasse Labrus bergylta, mass-length relationships were not different between genders, and positive allometry was found in the mixed-gender population. Male-biased sexual size dimorphism was significant and the most effective morphometric method for sexing L. bergylta outside of the species spawning window used body mass (M(B) in g), total body length (L(T) in mm) and Fulton's condition factor (K) as discriminant variables to predict gender with 91% accuracy. The discriminant score (S(D)) of a specimen can be calculated as S(D)  = 0.01 M(B)- 0.016 L(T)- 3.835 K + 6.252 to predict its gender as female or male if S(D) is < 1.459 or S(D) is > 1.504, respectively. There was a potential trend towards earlier sexual inversion compared to previous studies at comparable latitudes. Sex change is a phenotypically plastic trait under social control in haremic fishes and should be monitored in increasingly exploited L. bergylta.

Comparative study of pineal clock gene and AANAT2 expression in relation to melatonin synthesis in Atlantic salmon (Salmo salar) and European seabass (Dicentrarchus labrax)

The photoreceptive teleost pineal is considered to be essential to the generation, synchronisation and maintenance of biological rhythms, primarily via melatonin release. The role of internal (circadian clock) and external (light) signals controlling melatonin production in the fish pineal differs between species, yet the reasons underpinning this remain largely unknown. Whilst in salmonids, pineal melatonin is apparently regulated directly by light, in all other studied teleosts, rhythmic melatonin production persists endogenously under the regulation of clock gene expression. To better understand the role of clocks in teleost pineals, this study aimed to characterise the expression of selected clock genes in vitro under different photoperiodic conditions in comparison to in vivo in both Atlantic salmon (Salmo salar) and in European seabass (Dicentrarchus labrax) (in vitro 12L:12D), a species known to display endogenous rhythmic melatonin synthesis. Results revealed no rhythmic clock gene (Clock, Period 1 &2) expression in Atlantic salmon or European seabass (Clock and Period 1) pineal in vitro. However rhythmic expression of Cryptochrome 2 and Period 1 in the Atlantic salmon pineal was observed in vivo, which infers extra-pineal regulation of clocks in this species. No rhythmic arylalkylamine N-acetyltransferase 2 (Aanat2) expression was observed in the Atlantic salmon yet in the European seabass, circadian Aanat2 expression was observed. Subsequent in silico analysis of available Aanat2 genomic sequences reveals that Atlantic salmon Aanat2 promoter sequences do not contain similar regulatory architecture as present in European seabass, and previously described in other teleosts which alludes to a loss in functional connection in the pathway.

Do bone loss and reconstruction procedures differ at revision of cemented unicompartmental knee prostheses according to the use of metal-back or all-polyethylene tibial component?

INTRODUCTION

Results of unicompartmental knee arthroplasty (UKA) revision are known but the severity of bone loss and the need for reconstruction are not detailed for different tibial implants.

HYPOTHESIS

Metal-backing UKA revision exposes the patient to more severe tibial bone loss and requires more substantial reconstruction procedures than cemented polyethylene UKA revision.

MATERIALS AND METHODS

This retrospective series of 23 revisions of UKA to total knee arthroplasty (TKA) compared 11 all-polyethylene UKAs with 12 metal-backing UKAs. Factors that contributed to failure were aseptic loosening (n=12) and osteoarthritis evolution (n=11). Both groups were similar regarding the demographic and clinical features. We reported bone loss and the reconstruction procedure to fill it according to the initially used tibial implant. The results were evaluated with the IKS score to a follow-up of 37 months (range, 24-67 months).

RESULTS

There were more tibial segmental bone loss (10 versus 3) and more metal wedges (8/12 versus 2/11) in metal-backing UKA revision (P<0.05). Tibial stems were more often used in metal-backing UKA revision (12/12 versus 7/11) (P=0.04). The results of TKA at follow-up did not differ according to whether the revised tibial implant was all polyethylene (IKS=155 [range, 107-195]) or metal-back (IKS=155 [range, 127-172]).

DISCUSSION

This study suggests that metal-backing UKA revision exposes the patient to more severe tibial bone loss requiring more substantial reconstruction. These results must be confirmed on a larger population, but surgeons should be alerted to this kind of revision surgery, which warrants having available a revision knee prothesis.

LEVEL OF EVIDENCE

Level III, case-control study.

Bacterial epidemiology of osteoarticular infections in a referent center: 10-year study

INTRODUCTION

Management of osteoarticular infections combines surgical treatment with antibiotic therapy. For some teams the immediate postoperative regimen requires at least partly wide-spectrum probabilistic treatment while waiting for the microbiological results. This protocol exposes the patient to the selection of resistant bacteria and the hospital unit to a modification of its bacterial ecology. The objective of this study was to retrospectively describe the microbial epidemiology of the Traumatology and Orthopaedics Department of the Lille University Hospital over 10 years (2002-2011).

MATERIALS AND METHODS

The bacterial species isolated in culture of osteoarticular samples were listed, after removing any duplicates. The antibiotics retained for follow-up were those used in treatment of these infections as well as those recognized as markers of resistance. For Gram-positive species, the antibiotics considered were methicillin, rifampicin, fluoroquinolones, glycopeptides, and linezolid; for the Gram-negative species, cefotaxime, cefepime, imipenem, and fluoroquinolones were considered.

RESULTS

Of the 5006 strains isolated between 2002 and 2011, Gram-positive cocci accounted for more than 71%; Staphylococcus aureus 27%, and coagulase-negative staphylococci (CoNS) 54%. Contrary to S. aureus, resistance to methicillin, fluoroquinolones, and teicoplanin significantly increased in CoNS, reaching 44%, 34%, and 22%, respectively, of the strains in 2011. The proportion of streptococcal and enterococcal infections remained stable, a mean 7.4% and 5.3%, respectively, per year. Enterobacteria (12.5% of the isolates) were producers of extended-spectrum beta-lactamase in 7.8% of the cases. Pseudomonas aeruginosa was involved in 3.6% of the infections, and 12% of the strains remained resistant to ceftazidime. Propionibacterium acnes accounted for 5.8% of the bacteria isolated and showed few antibiotic resistance problems.

DISCUSSION

Stability in the distribution and the susceptibility of different bacterial species was noted over this 10-year period. Although the evolution of S. aureus resistance was favourable, the resistance of CoNS specially to methicillin and glycopeptides increased.

LEVEL OF EVIDENCE

Level IV. Retrospective cohort study.

Incidental discovery of an undisplaced ceramic liner fracture at total hip arthroplasty revision for squeaking

Squeaking has been reported after ceramic-on-ceramic total hip arthroplasty (THA), but its pathomechanics is not fully understood. Impaired lubrication is suspected to be the main reason. The management of patients impacted by this phenomenon is not well defined and, as it is not considered to be cause for alarm, revision is not strongly recommended. Here, we describe a ceramic insert fracture discovered during revision surgery performed to correct severe squeaking. Preoperative investigation (plain X-rays, ultrasound and computed tomography) did not reveal ceramic fracture or definite component malposition. To date, there are no other published cases of incidental discovery of a bearing component fracture during revision of ceramic-on-ceramic hip replacement due to squeaking. We believe that squeaking is not a trivial phenomenon and recommend careful management of patients suffering with this symptom.

Knee arthrodesis using a customised modular intramedullary nail in failed infected total knee arthroplasty

BACKGROUND

Knee arthrodesis is used to treat patients with failed infected total knee arthroplasty (TKA). Among fixation methods, intramedullary nailing increases the chances of bone union but may carry a risk of infection around the nail. This risk is not well understood, because available case-series studies were not confined to patients with knee infection.

HYPOTHESIS

Infection recurrence rates after knee arthrodesis with intramedullary nailing used to treat failed infected TKA are similar to those seen with other fixation methods.

METHODS

We retrospectively reviewed 31 cases of knee arthrodesis with fixation by a modular intramedullary nail performed at a subspecialized center treating complex osteoarticular infections (CRIOAC). The antibiotic regimen was determined based on multidisciplinary discussions and microbiological studies of preoperative and intraoperative specimens. Mean follow-up was 50 ± 22 months (range, 28-90 months). Arthrodesis was performed in one stage (n=6) or two stages (n=25). Success was defined as presence, after a postoperative follow-up of at least 24 months, based on the following criteria: normal erythrocyte sedimentation rate and/or C-reactive protein, no wound inflammation or sinus tract, no revision surgery, and no antibiotic treatment. Bone union was not a criterion for a successful arthrodesis procedure.

RESULTS

Removal of the fixation material was required in three patients and long-term palliative antibiotic therapy in three patients (fixation material in place with repeated positive specimens) for a total of six failures due to infection (6/31, 19.4%). None of the patients experienced mechanical failure (no breakage of the material and no fixation failure of the nails designed to allow osteointegration). The mean leg length discrepancy was 10 ± 10 mm (range, 5-34 mm) and the mean Oxford score was 41 ± 11 (range, 23-58). The 50-month rate of arthrodesis survival to revision surgery for nail removal was 77.8 ± 4% and the 50-month rate of arthrodesis survival without revision surgery for persistent infection was 74.6 ± 4.2%.

DISCUSSION

The infection recurrence rate was higher than with other fixation methods but remained acceptable (19.4%). Use of a modular intramedullary nail prevented major leg-length discrepancies, which are often poorly accepted by the patients, and allowed immediate weight bearing despite the often severe bone loss.

LEVEL OF EVIDENCE

Level IV, retrospective cohort study.

Poor short-term outcomes after computer-assisted rotating-platform total knee arthroplasty with a deep-trochlear-groove femoral component: analysis of 19 patients

BACKGROUND

Congruent rotating tibial plateaus are designed to minimise wear after total knee arthroplasty (TKA). The Score™ prosthesis has a congruent rotating tibial plateau, a deep trochlear groove, and uses a computer-assisted navigation system for ligament balancing. Although this prosthesis is widely utilized, no accurate data on outcomes are available.

HYPOTHESIS

The innovative features of the Score™ prosthesis, most notably patellar replacement with a highly constrained femoral component, do not jeopardize implant survival.

PATIENTS AND METHODS

In a pilot study, we retrospectively evaluated outcomes of 19 patients treated with Score™ knee replacement between February and October 2006 (mean age, 66.8 years; range, 58-82 years). The evaluation criteria were the International Knee Society (IKS) scores and prosthesis survival rate estimated using Kaplan-Meier plots with failure defined as revision need to change the prosthesis.

RESULTS

Mean follow-up was 35.3 months. The IKS knee score increased from 27.4 (5-60) preoperatively to 81.4 (45-99) at last follow-up (P<0.0001). Mean mechanical axis was 181.2° (180-186°), with 16 between 180° and 183°. Revision surgery was required in five cases (for patellar complications with combined motion-range limitation in flexion (<90°) and extension (5-20°) in three cases, isolated motion-range limitation in one case, and recurvatum deformity with instability in one case). Prosthesis survival was 82% (73-91%) after 24 months and 65% (51-78%) after 44 months.

DISCUSSION

The deep trochlear groove femoral component resulted in patellar complications, which were the most common reasons for revision surgery, together with motion-range limitation and instability possibly related to improper use of the navigation system. This small retrospective case-series study showed an unusually low prosthesis survival rate probably related to the implant design. We no longer use the Score™ prosthesis, despite the availability of a dedicated navigation system, and we recommend careful monitoring of patients who have this prosthesis.

LEVEL OF EVIDENCE

Level IV, retrospective study.

Major amputation of lower extremity: prognostic value of positive bone biopsy cultures

BACKGROUND

To assess the correlation between culture results of section's osseous slice biopsy (SOB) and the distal infected site responsible for the amputation performed concomitantly during major amputation of lower extremity. The influence of a positive culture of SOB on the patients' outcome was also evaluated.

MATERIALS AND METHODS

We conducted a retrospective study of medical charts of patients who underwent SOB during major amputation of lower extremity at our institution from 2000 to 2009.

RESULTS

Fifty-seven patients (42 males/15 females, mean age 52.16years) who undergone major limb amputation (47 below knee and ten above knee) were included. The initial medical conditions of the investigated patients were: trauma (n=32), infection (n=13), trophic disorders (n=10) and tumor (n=2). The major cause of amputation was an uncontrolled infection, accouting for 64.9% of the cases (37/57) (foot=5, ankle=8, leg=24), the remaining 20 patients had trophic disorders of lower limb. Twenty-one (36.8%) from 57 biopsies were sterile, 12 (21.1%) doubtful and 24 (42.1%) positive. Thirty-one (54.4%) patients had an antibiotic-free interval before limb amputation. Independently of the bacterial species, 69.6% of the microorganisms identified from SOB were found in the distal infected site. Patients with positive SOB had a significantly longer interval between the decision to amputate the patient and the surgical procedure (200.2 vs. 70.1days; P<0.03) and a shorter total duration of antibiotic therapy before amputation than patients with negative SOB (3.68 vs. 6.08months; P<0.03). The delay for complete healing was significantly higher in patients with a positive SOB compared with those with a negative SOB (3.57 vs. 2.48months; P<0.03).

CONCLUSION

Our results suggest that the infection may extend from the distal site to the level of amputation in a large proportion of cases and that the delay with which the amputation is performed after the decision has been taken may play a role in this event.

LEVEL OF EVIDENCE

Study level IV: retrospective observationnal study.