G. Pasquier

Three-dimensional hip anatomy in osteoarthritis. Analysis of the femoral offset.

Two hundred twenty-three patients with osteoarthritic hips were analyzed using computed tomography and a specific image processing software (HIP-PLAN) to determine 3-dimensional morphological data of the hip focusing on femoral offset (FO). Mean FO was found to be 42.2 +/- 5.1 mm, 2.2 mm greater than the 2-dimensional FO values reported in the literature. The FO was found to be above 45 mm in 31% of patients and greater than 50 mm in 12%. The error associated with the use of conventional plane x-rays to measure FO was found to be 3.5 +/- 2.5 mm, the x-ray technique generally underestimating the measure of FO. The sum of acetabular and femoral anteversion was found to be out of the safe zone regarding dislocation risk in 47% of patients.

Opening wedge high tibial osteotomy performed without filling the defect but with locking plate fixation (TomoFix™) and early weight-bearing: prospective evaluation of bone union, precision and maintenance of correction in 51 cases.

INTRODUCTIONnA medial opening wedge high tibial osteotomy (HTO), where the osteotomy site is filled, is often preferred to a lateral closing osteotomy, but filling the defect can lead to certain complications.nnnHYPOTHESISnA medial opening HTO can be performed without filling the bone defect if fixation is carried out with a specially-designed stiff locking plate.nnnPATIENTS AND METHODSnFifty-one patients, 37 to 72 years of age where followed prospectively and continuously from 2003 to 2006. A single surgical technique was used: medial opening HTO with locked plate fixation (TomoFix™, Synthes) but without filling the defect. The preoperative genu varum could not exceed 15°. The following were evaluated: time to return to weight-bearing, IKS functional score, long-leg standing film performed preoperative, postoperative and at follow-up to evaluate limb alignment and validate the precision of the correction and its stability over time. A measurement of the area of bone union in the osteotomy site was used to quantify the rate of union.nnnRESULTSnBone union occurred at 4.5 months on average; two cases of incomplete union (7%) were found and revised with an autograft at 7 and 9 months. Lower-limb alignment was 7.5° of varus on average before surgery (3° to 15° varus, SD=2.85) and 1.2° of valgus on average after the surgery (4° varus to 5° valgus, SD=1.78). The correction was maintained at 1 year post-surgery. The average IKS knee score went from 69±15.5 (range 25 to 96) before surgery to 90±7.4 (range 66 to 98) at follow-up (P=0.0001). Full weight-bearing without assistance was possible after 3 months on average (range 1.5 to 8, SD=1.21). Forty-seven patients (92%) were fully weight-bearing after 2 months. Forty-eight patients were able to return to work and sporting activities at the same or a higher level than before the procedure.nnnDISCUSSIONnBone union seems to happen more slowly when the defect is filled; however, there are doubts about radiological evaluation of bone union in different published studies. When osteotomy defect was left unfilled in this study, union and filling of 4/5 of the osteotomy site was obtained in 4.2 months for 49 of the 51 cases. Fixation with the locking plate is reliable and provides stable correction and the option for early weight-bearing.

Total hip arthroplasty offset measurement: Is C T scan the most accurate option?

BACKGROUNDnFemoral offset is difficult to precisely evaluate with conventional X-ray techniques. Femoral offset characterizes the balance between body weight and the resistance provided by the abductor muscles. Total hip arthroplasties should respect this balance.nnnHYPOTHESISnComputed tomodensitometry (CT-scan) is more accurate than conventional X-ray to evaluate femoral offset.nnnMATERIALS AND METHODSnSixty-one patients who received unilateral total hip arthroplasties were prospectively included in the study. Femoral offset was measured by three-dimensional CT-scan reconstruction using the Hip Plan (Symbios) software. Offset was also determined with conventional X-ray and results were compared. This software can be used to measure leg length by frontal telemetry. It was developed for preoperative-planning of cementless femoral stem implants with modular necks of various lengths and angles. All pre- and postoperative measurements were made according to the same protocol.nnnRESULTSnFemoral offset values in this study were very similar to anatomical values found in the literature. They were significantly higher than values obtained by conventional X-ray by an average of 8%. Implantation of hip replacements resulted in a significant increase in offset (1.88+/-4.71 mm) with a slight variation in leg length. Pre- and postoperative leg length increased slightly in the operated leg by an average of 1.66+/-5.63 mm. Seventeen percent of these femurs had high offset associated with small or average sized proximal medullary canals. This preoperative planning software made it possible to identify these difficulties and to adapt implant components using modular long 8 degrees varus necks to restore high offset. In most of these cases, only small femoral stems could be implanted because of the small size of the intramedullary femoral canal. These individual differences were identified with 3D CT-scan reconstruction and included in the preoperative planning. Moreover, leg length could also be evaluated with this method and included in the preplanning.nnnDISCUSSIONnCompared to conventional X-ray, measurements obtained with this preoperative planning method using 3D CT-scan reconstruction are easy to obtain and not dependent upon test conditions because the frame is placed on the femoral axis. Measurements are not influenced by position inconsistencies or if the hip is fixed in external rotation. The significant number of cases with above average offset confirms the importance of obtaining these measurements and the necessity of adapting the strategy in these cases by using lateralized stems, or, as in our series, modular necks to adjust femoral offset and neck angle.nnnLEVEL OF EVIDENCEnLevel III diagnostic prospective study.

Total knee arthroplasty in valgus knees: predictive preoperative parameters influencing a constrained design selection.

INTRODUCTIONnIn valgus knees, ligament balance might remain a challenge at total knee prostheses implantation; this leads some authors to systematically propose the use of constrained devices (constrained condylar knee or hinge types...). It is possible to adapt the selected level of constraints, by reserving higher constraints to cases where it is not possible to obtain final satisfactory balance: less than 5 degrees of residual frontal laxity in extension in each compartment, and a tibiofemoral gap difference not in excess to 3 mm between flexion and extension.nnnHYPOTHESISnIt is possible to establish preoperative criteria that can predict a constrained design prosthetic implantation at surgery.nnnMATERIALS AND METHODSnA consecutive series of 93 total knee prostheses, implanted to treat a valgus deformity of more than 5 degrees was retrospectively analysed. Preoperatively, full weight bearing long axis AP views A-P were performed: hip knee angle (HKA) averaged 195 degrees (186 degrees to 226 degrees), 36 knees had more than 15 degrees of valgus, and 19 others more than 20 degrees of valgus. Laxity was measured by stress radiographies with a Telos system at 100 N. Fifty-two knees had preoperative laxity in the coronal plane of more than 10 degrees. Fourteen knees had more than 5 degrees laxity on the convex (medial) side, 21 knees had more than 10 degrees laxity on the concave (lateral) side. Statistical assessment, using univariate analysis, identified the factors that led, at surgery, to an elevated constraint selection level; these factors of independence were tested by multivariate analysis. Logistical regression permitted the classification of the said factors by their odds ratios (OR).nnnRESULTSnHigh-constraints prostheses (CCK type) numbered 26 out of 93 implantations; the other total knee prostheses were regular posterostabilized (PS) prostheses. Statistically, the preoperative factors that led to the choice of a constrained prosthesis were: (1) valgus severity as measured by HKA (PS=193 degrees, CCK=198 degrees), (2) increased posterior tibial slope (PS=4.8 degrees, CCK=6.5 degrees), (3) low patellar height (using Blackburne and Peel index PS=0.89, CCK=0.77), (4) severity of laxity in valgus (PS=2.3 degrees, CCK=4.3 degrees). Among all these factors, the only independent one was laxity in valgus (convex side laxity) (p=0.0008). OR analysis showed a two-fold increased probability of implanting an elevated constraints prosthesis for each one degree increment of laxity in valgus.nnnDISCUSSIONnThis study demonstrated that it was not the valgus angle severity but rather the convex medial side laxity that increased the frequency of constrained prostheses implantation. Other factors, as a low patellar height or an elevated posterior tibial slope, when associated, potentiate this possible prosthetic switch (to higher constraints) and should make surgeons aware, in these situations, of encountering difficulties when establishing ligament balance.nnnLEVEL OF EVIDENCE IVnTherapeutic retrospective study.

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

INTRODUCTIONnTrochlear 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.nnnHYPOTHESISnSulcus deepening trochleoplasty is an effective procedure to stabilize the patellofemoral joint that does not increase the risk of osteoarthritis.nnnPATIENTS AND METHODSnThis 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).nnnRESULTSnNo 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%).nnnDISCUSSIONnSulcus 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.

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.

Long-term outcomes of primary constrained condylar knee arthroplasty

BACKGROUNDnAlthough 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.nnnHYPOTHESISnIncreasing constraint by implantation of a CCK insert does not increase the long-term frequencies of osteolysis or mechanical loosening.nnnMATERIAL AND METHODSnWe 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.nnnRESULTSnComplications 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.nnnDISCUSSIONnLong-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.

De-escalation exchange of loosened locked revision stems to a primary stem design: Complications, stem fixation and bone reconstruction in 15 cases

INTRODUCTIONnFemoral stem revision with a locked stem after total hip arthroplasties treats severe bone defects by favoring spontaneous bone reconstruction. Initially, once reconstruction was obtained, the temporary implant was to be replaced by a standard primary component. The use of locked stems has increased, but repeat revision with a short stem which is also called de-escalation has not been extensively studied.nnnHYPOTHESISnRepeat revision of a locked stem with a short stem is not associated with any specific morbidity and does not affect the quality of reconstruction obtained, or fixation of the subsequent standard length primary design stem.nnnPATIENTS AND METHODSnFifteen patients whose locked femoral stem was exchanged due to thigh pain and/or radiographic images showing failed osteointegration were analyzed. These 15 patients were all followed-up and evaluated by the Postel Merle dAubigné score. Progression of bone defects was evaluated using the Hofmann cortical index.nnnRESULTSnThere were no difficulties extracting the locked stem and a standard length primary stem was inserted with no associated procedures or bone complications in any of the cases. At a mean follow-up of 55 months (36-84months), thigh pain had disappeared and the Postel Merle dAubigné score had increased from 12.6±2.9 (7-16) to 16.5±0.9 (15-18) (P=0.0001). The use of a locked femoral stem resulted in bone reconstruction in all cases, the Hofmann index increased from 30.5%±17.9% (12-71%) before insertion of the locked stem to 43.6%±25.6% (19-90%) at exchange (P<0.05). Bone reconstruction was durable after the exchange with a stable Hofmann index 43.7%±26.2% (17-92%) at the final follow-up (P=0.9). No recurrent loosening occurred.nnnDISCUSSIONnRevision of a loosened locked femoral stem with a standard design primary stem does not result in any specific increased morbidity, or modify bone reconstruction obtained with the locked stem and results in stable fixation of a new standard length stem.nnnLEVEL OF EVIDENCEnIV: retrospective or historical series.

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?

INTRODUCTIONnResults 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.nnnHYPOTHESISnMetal-backing UKA revision exposes the patient to more severe tibial bone loss and requires more substantial reconstruction procedures than cemented polyethylene UKA revision.nnnMATERIALS AND METHODSnThis 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).nnnRESULTSnThere 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]).nnnDISCUSSIONnThis 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.nnnLEVEL OF EVIDENCEnLevel III, case-control study.

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

INTRODUCTIONnMedial 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.nnnHYPOTHESISnTrochlear spur does not affect outcome in PFI managed by MPFL reconstruction and ATTT.nnnMATERIAL AND METHODSnTwenty-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.nnnRESULTSnAt 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).nnnCONCLUSIONnMPFL 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.nnnLEVEL OF EVIDENCEnIII, retrospective case-control study.