Coronal Malalignment in the Adult Knee

Coronal plane deformity in the adult patient is a complex clinical problem. Once the hip, knee, and ankle joint centers lose collinerarity, the knee is exposed to abnormal loads across its tibiofemoral compartments, leading to early degenerative changes. Malalignment can coexist with arthrosis and ligamentous instability. High tibial osteotomy and distal femoral osteotomy have been useful tools to realign the adult knee. They can be performed along with ligament reconstruction and cartilage restoration procedures with high success rates. Despite novel techniques and fixation methods, principles of deformity correction should be followed to maximize clinical outcomes.

Effect of Pedal Deformity on Gait in a Patient With Total Knee Arthroplasty

The authors present the case of an 81-year-old man who, despite an anatomically aligned total knee arthroplasty, continued to have knee pain. The patient's ipsilateral rigid flatfoot caused by an earlier partial pedal amputation resulted in a valgus moment during gait, thus creating clinical symptoms in the total knee arthroplasty. Because of the deformity and scarring within the flatfoot, this valgus deformity was corrected through a varus distal femoral osteotomy. The result was normalization of the mechanical axis of the lower limb and a pain-free total knee arthroplasty with an excellent clinical outcome. This case shows the importance of comprehensive lower-extremity clinical and radiographic examination as well as gait analysis to understand the biomechanical effect on total knee arthroplasty. Recognition of pedal deformities and lower limb malalignment is paramount for achieving optimal outcomes and long-term success of total knee arthroplasty. The authors show that a rigid or nonflexible pedal deformity can have negative biomechanical effects on total knee arthroplasty.

Prospective comparative study of two methods for fixation after distal femur corrective osteotomy for valgus deformity; retrograde intramedullary nailing versus less invasive stabilization system plating

INTRODUCTION

The aim of this study was to compare the radiological and functional results of two different methods of fixation for the correction of femoral valgus deformities.

METHODS

Patients who had undergone osteotomy and correction of a valgus deformity from 2007 to 2013 were prospectively followed. Thirty three patients (20 females, 13 males) with 39 lower limbs were included in the study. Seventeen lower limbs were treated with retrograde intramedullary nailing (IMN) and 22 with less invasive stabilization system plating. Standing orthoroentgenograms of the lower limbs were taken pre-operatively and at the final follow-up. mLDFA, aLDFA, mechanical axis deviation (MAD) were measured in this orthoroentgenograms. Knee osteoarthritis outcome score (KOOS) and knee range of motion were used pre-operatively and at the final follow-up as part of the evaluation of the clinical results. All patients duration of surgery, length of hospital stay were assessed. Operations were performed by two orthopedic surgeons. The choice of correction method for each patient was determined by the surgeon. Pre-operative and post-operative values were simultaneously measured by two additional orthopedic surgeons.

RESULTS

The mean age of the patients was 26.2 years (18.0-51.0) in the plating group and 29.3 years (18.0-55.0) in the nailing group. Patients in the plating and nailing groups were followed up for 24.0 (12.0-60.0) and 27.8 (12.0-60.0) months. All patients were followed for a minimum of 12 months. No significant differences were observed between the groups in terms of age, sex, or duration of follow-up (p > 0.05) Comparison of the pre- and post-operative mLDFA, aLDFA, MAD, length of hospital stay, and duration of surgery between the plating group and nailing group, no significant difference was observed between the groups (p > 0.05). However, patients treated with retrograde IMN had significantly better post-operative results in terms of the KOOS and range of motion of the knee according to plating group (p < 0.05).

CONCLUSION

Retrograde IMN does not provide a radiological advantage over the LISS plating technique for valgus deformity but retrograde IMN and correction offered better functional results in cases of femoral valgus deformity than did the LISS plating method.

Prevention of inaccurate targeting of proximal screws during reconstruction femoral nailing

PURPOSE

The purpose of this study was to identify the underlying cause by simulating the forces involved in a controlled laboratory setting, and then to illustrate some intraoperative tips on how to detect this malalignment and suggest solutions prevent this intraoperative complication.

METHODS

The Expert Asian Femoral Nail (A2FN) and Proximal Femoral Nail Antirotation (PFNA) reconstruction nail systems were evaluated to compare the characteristics of each nailing system and their reactions to soft tissue tension at the time of proximal reconstruction screw placement. Soft tissue tension was simulated by placing a fulcrum under the distal drill sleeve and exerting a load on the targeting device via the addition of weights. The occurrence and degree of guide malalignment were determined while gradually increasing the weight.

RESULTS

When soft tissue tension was simulated on the drill/guide sleeve of the A2FN, the drill sleeve deviated from the proximal screw hole proportionally to the weight applied and the K-wire guide passed outside of the nail at a weight of 7 kg. However, the drill sleeve of the PFNA was aligned exactly to the center of nail axis and the K-wire passed cleanly through the proximal locking hole regardless of weight applied.

CONCLUSIONS

Inaccurate guidance of the screw-targeting device can be caused by soft tissue tension. Thus, the authors recommend that careful attention be placed on minimizing soft tissue tension during proximal screw placement while using the targeting device of the A2FN system.

The current role of coronal plane alignment in Total Knee Arthroplasty in a preoperative varus aligned population: an evidence based review

BACKGROUND

Based on historical data, the current standard of care in Total Knee Arthroplasty (TKA) is to restore the overall alignment to a neutral mechanical axis of 0°±3° or even slight valgus. However, there is significant controversy in literature regarding intentionally placing the TKA in the patient's physiologic, rather than neutral (0±3°), mechanical alignment.

QUESTIONS/PURPOSES

The goal of this review is to provide a concise update on the present knowledge of coronal plane alignment TKA in a varus population.

METHODS

A systematic overview of the present literature was undertaken to determine basic science and clinical results in frontal plane alignment in primary TKA.

RESULTS

Results of studies based on laboratory research, retrieval analysis, cadaver research, finite models, survival scores, clinical outcome, gait analysis and radiographic outcome upon today are provided.

CONCLUSIONS

Currently placement of a TKA in neutral alignment of 0°±3° of frontal plane alignment is the standard of care. However, frontal plane alignment in neutral may not be as strongly correlated to survivorship as previously thought. Caution needs to be exercised before changing the standard of care, and more research needs to be performed.

Supramalleolar Osteotomies for Posttraumatic Malalignment of the Distal Tibia

Supramalleolar osteotomies of the tibia (SMOT) for posttraumatic distal tibial malalignment has shown to reduce pain, improve function and radiographic signs of osteoarthritis, and delay ankle arthrodesis or total joint replacement. The procedure also protects the articular cartilage from further degenerative processes by shifting and redistributing loads in the ankle joint. It is technically demanding and requires extensive preoperative planning. The type of osteotomy (opening vs closing wedge) does not influence the final outcome. However, based on the limited evidence, a grade I treatment recommendation has been given for supramalleolar osteotomies of the tibia to treat mild to moderate ankle arthritis in the presence of distal tibial malalignment.

Correlation between varus knee malalignment and patellofemoral osteoarthritis

PURPOSE

To evaluate the relationship between patellofemoral osteoarthritis (OA) and varus OA of the knee with a focus on the location of joint space narrowing.

METHODS

Eighty-five patients scheduled to undergo total knee arthroplasty caused by varus OA were enrolled in this study. The relationship between patellofemoral OA and varus knee malalignment was elucidated. To determine the alignment of the patellofemoral joint in varus knees, patellar tilt, and the tibial tuberosity-trochlear groove (TT-TG) distance were measured, and patellofemoral OA was classified using computed tomography.

RESULTS

The femorotibial angles in patients with stage II-IV patellofemoral OA were significantly larger than those in patients with stage I patellofemoral OA, and the patellar tilt in patients with stage II-IV patellofemoral OA and the TT-TG distance in patients with stage IV patellofemoral OA were significantly larger than those in patients with stage I patellofemoral OA. The TT-TG distance was strongly correlated with patellar tilt (R(2) = 0.41, P < 0.001). Patellofemoral joint space narrowing was mainly noted at the lateral facet, and it was found on both sides as patellofemoral OA worsened.

CONCLUSION

Varus knee malalignment was induced by patellofemoral OA, especially at the lateral facet. Patellar tilt and the TT-TG distance are considered critical factors for the severity of patellofemoral OA. Understanding the critical factors for patellofemoral OA in varus knees such as the TT-TG distance and patellar will facilitate the prevention of patellofemoral OA using procedures such as high tibial osteotomy and total knee arthroplasty to correct knee malalignment.

LEVEL OF EVIDENCE

Retrospective cohort study, Level III.

Effect of high tibial osteotomy on joint loading in symptomatic patients with varus aligned knees: a study using SPECT/CT

PURPOSE

The purpose was to prospectively evaluate the outcome, in particular the SPECT/CT bone tracer uptake (BTU) after high tibial osteotomy (HTO) due to symptomatic varus malalignment. It was the hypothesis that the BTU after HTO decreases in the medial compartment, clinical outcome and the degree of correction correlates with BTU and asymptomatic patients after HTO reveals a significantly decreased BTU in the medial subchondral areas.

METHODS

Twenty-two consecutive patients with 23 knees undergoing medial opening-wedge HTO for medial compartment overloading were assessed pre- and postoperatively (12 and/or 24 months) using Tc-99m-HDP-SPECT/CT including our 4D-SPECT/CT protocol. BTU was quantified and localized to specific biomechanically relevant joint areas. Maximum absolute and relative values (mean ± standard deviation, median and range) for each area were recorded. Pre- and postoperative mechanical alignment was measured. At 24 months after HTO, the WOMAC score was used.

RESULTS

A significant decrease of BTU in the medial subchondral zones after HTO was found (preoperatively to 12 and 24 months postoperatively, p < 0.01). BTU normalized in all asymptomatic patients within 24 months. This decrease was partly seen in the lateral compartments, but significantly higher in the medial compartments (p < 0.0001). A significant increase of the BTU was noted in zones directly adjacent to the plate or within the osteotomy zone (p < 0.01). Decreased BTU was observed in osteotomy zones at 24 months postoperatively following higher uptake values at 12 months postoperatively. The average valgus correction of the tibiofemoral angle was 5.9° ± 2.8°. Less stiffness correlated significantly with a higher decrease in BTU (p < 0.05). Higher postoperative BTU significantly correlated with more pain (p < 0.05). No statistical significant associations between BTU and alignment correction were found.

CONCLUSION

In patients with medial compartment, overloading due to varus malalignment HTO led to a significant decrease in BTU in the medial joint compartments. SPECT/CT BTU patterns and intensity in these patients pre- to 12 and 24 months postoperatively were seen. These correlated significantly with pain and stiffness. Hence, SPECT/CT could be used for assessment of adequate correction and healing after HTO. SPECT/CT could be further used to identify the optimal individualized correction for each patient and clinical scenario.

CLINICAL EVIDENCE

Diagnostic prospective study, Level II.

Image-Based Techniques for Percutaneous Iliosacral Screw Start-Site Localization

Despite the routine use of iliosacral screws for the treatment of a variety of pelvic fractures, the technique is demanding, and complications are well described. This article describes a novel image-based technique for accurately identifying and reproducing the appropriate placement of iliosacral screws. Using the stab-incision technique presented here allows for more accurate landmark identification and safer placement of implants.

Assessing Lower Limb Alignment: Comparison of Standard Knee Xray vs Long Leg View

BACKGROUND

High tibial osteotomy (HTO) is a well-established and commonly utilized technique in medial knee osteoarthritis secondary to varus malalignment. Accurate measurement of the preoperative limb alignment, and the amount of correction required are essential when planning limb realignment surgery. The hip-knee-ankle angle (HKA) measured on a full length weightbearing (FLWB) X-ray in the standing position is considered the gold standard, since it allows for reliable and accurate measurement of the mechanical axis of the whole lower extremity. In general practice, alignment is often evaluated on standard anteroposterior weightbearing (APWB) X-rays, as the angle between the femur and tibial anatomic axis (TFa). It is, therefore, of value to establish if measuring the anatomical axis from limited APWB is an effective measure of knee alignment especially in patients undergoing osteotomy about the knee.

METHODS

Three independent observers measured preoperative and postoperative FTa with standard method (FTa1) and with circles method (FTa2) on APWB X-ray and the HKA on FLWB X-ray at three different time-points separated by a two-week period. Intra-observer and inter-observer reliabilities and the comparison and relationship between anatomical and mechanical alignment were calculated.

RESULTS

Intra- and interclass coefficients for all the three methods indicated excellent reliability, having all the values above 0.80. Using the mean of paired t-student test, the comparison of HKA versus TFa1 and TFa2 showed a statistically significant difference (p<.0001) both for the pre-operative and post-operative sets of values. The correlation between the HKA and FTal was found poor for the preoperative set (R=0.26) and fair for the postoperative one (R=0.53), while the new circles method showed a higher correlation in both the preoperative (R=0.71) and postoperative sets (R=0.79).

CONCLUSIONS

Intra-observer reliability was high for HKA, FTal and FTa2 on APWB x-rays in the pre- and post-operative setting. Inter-rater reliability was higher for HKA and TFa2 compared to FTal. The femoro-tibial angle as measured on APWB with the traditional method (FTal) has a weak correlation with the HKA, and based on these findings, should not be used in everyday practice. The FTa2 showed better correlation with the HKA, although not excellent.

LEVEL OF EVIDENCE

Level III, Retrospective study.

Tibial component alignment and risk of loosening in unicompartmental knee arthroplasty: a radiographic and radiostereometric study

PURPOSE

Unicompartmental knee arthroplasty (UKA) has shown a higher rate of revision compared with total knee arthroplasty. The success of UKA depends on prosthesis component alignment, fixation and soft tissue integrity. The tibial cut is the crucial surgical step. The hypothesis of the present study is that tibial component malalignment is correlated with its risk of loosening in UKA.

METHODS

This study was performed in twenty-three patients undergoing primary cemented unicompartmental knee arthroplasties. Translations and rotations of the tibial component and the maximum total point motion (MTPM) were measured using radiostereometric analysis at 3, 6, 12 and 24 months. Standard radiological evaluations were also performed immediately before and after surgery. Varus/valgus and posterior slope of the tibial component and tibial-femoral axes were correlated with radiostereometric micro-motion. A survival analysis was also performed at an average of 5.9 years by contacting patients by phone.

RESULTS

Varus alignment of the tibial component was significantly correlated with MTPM, anterior tibial sinking, varus rotation and anterior and medial translations from radiostereometry. The posterior slope of the tibial component was correlated with external rotation. The survival rate at an average of 5.9 years was 89%. The two patients who underwent revision presented a tibial component varus angle of 10° for both.

CONCLUSIONS

There is correlation between varus orientation of the tibial component and MTPM from radiostereometry in unicompartmental knee arthroplasties. Particularly, a misalignment in varus larger than 5° could lead to risk of loosening the tibial component.

LEVEL OF EVIDENCE

Prognostic studies-retrospective study, Level II.

Osteotomy of the spine for multifocal deformities

INTRODUCTION

When a deformity involves more than one area of the spine, it becomes a multifocal deformity; such a deformity could either be extending on two adjacent segments, or be two separated deformities on two non-adjacent segments.

MATERIALS AND METHODS

The surgical management of multifocal spinal deformities is challenging and must be done through a thorough preoperative planning where spinal and pelvic parameters should accurately be determined. Different strategies should be applied depending on the type of the multifocal deformity, the area involved, the angulation and stiffness of the spine in that area, and the presence of either a pure sagittal malalignment or a combined coronal and sagittal malalignment. This paper discusses these strategies and gives guidelines regarding the use of the different osteotomy techniques depending on each different situation that the deformity spine surgeon may encounter. For instance, where is the ideal level to perform a pedicle subtraction osteotomy (PSO) in a multifocal deformity? How does one take advantage of the remaining high discs to increase the correction without the need for a second PSO? When and where does one perform an asymmetrical PSO? When and where does one perform two PSOs? How does navigation help the spine surgeon to push the surgical limits further in these complex cases?

CONCLUSION

All these questions about the management of multifocal deformities will be discussed and answered with technical details and concrete examples of the different situations that may be encountered.

Stimulation of bone union with dynamic beams of Konzal's "R" external fixator

BACKGROUND

Treatment of septic long bone non-union remains a complex therapeutic problem. External stabilisation with Konzal's "R" fixator has been used in the Orthopaedic Department of CPME for years and allows for rigid stabilisation of bone fragments and good mutual alignment. Tried and tested in the treatment of osteitis, the fixator, however, offers limited possibilities for dynamisation and interfragmental compression. The following article presents a modernised design of Konzal's "R" with dynamic beams.

MATERIAL AND METHODS

The efficacy of dynamisation of the fixator with the modernised design was compared with that of the earlier technique of eccentric shifting of static beams by assessing the time of bone union, the average number of pin restabilisations required, and the percentage of "partial unions" in two groups treated with the different methods.

RESULTS

In the dynamic beam group, mean time to bone union was shorter by 5.1 months on average. This group also recorded a significantly lower percentage of "partial unions" (<50% of diaphysial circumference) as well as a lower count of necessary pin restabilisations per patient. There was no correlation between time to bone union and the duration of active inflammation prior to the surgical treatment or the presence of an open fistula.

CONCLUSIONS

1. The modernised design allows for dynamic load bearing by the bone tissue between the fragments rather than by the fixator's static beams. 2. The biomechanical principle of the fixator provides for optimal bone healing and shortens the time to bone union.

The minimally invasive far medial subvastus approach for total knee arthroplasty in valgus knees

PURPOSE

The lateral approach in the valgus knee asks for a lot of soft tissue releases during the arthrotomy. The hypothesis of this study was that the far medial subvastus approach could be used in valgus knees and would guarantee both functional and radiological good to excellent results.

METHODS

This is a retrospective study on 78 patients (84 knees) undergoing primary total knee arthroplasty (TKA) for type I or II fixed valgus knees. The mean (SD) preoperative mechanical alignment was 187° (4°) HKA angle. Functional recovery, pain, tourniquet times, necessary soft tissue releases as well as radiological alignment were measured.

RESULTS

The Knee Score improved significantly from 45 (10) to 90 (10) (P < 0.05) and the function score improved as well from 35 (20) to 85 (10) (P < 0.05). Flexion improved from 110° (10°) to 137° (8°). Hospital stay was 4 (1.2) days. Alignment was corrected to 181° (1.5°) HKA angle with a postoperative joint line shift of +2.8 (3.2) mm. No clinical instability, as evaluated by the senior author, or osteolytic lines was observed at minimal one-year radiological follow-up.

CONCLUSION

The far medial subvastus approach is an excellent approach to perform Krackow type I and II TKA with primary PS implants.

Progressive valgus angulation of the ankle secondary to loss of fibular congruity treated with medial tibial hemiepiphysiodesis and fibular reconstruction

The fibula is an important stabilizer of the lateral ankle. Discontinuity of the fibular shaft can lead to progressive pain and shortening of the fibula, ultimately causing loss of lateral support to the ankle. Two children, who sustained segmental bone loss of the shaft of the fibula, developed progressive symptomatic valgus of the ankle with widening of the mortice and lateral subluxation of the talus. Both patients were treated with fibular plating and grafting with tricalcium sulfate with acute reconstitution of fibular length. Distal medial tibial hemiepiphysiodesis was simultaneously performed. One patient required revision plating and grafting 14 months after the index surgery because of plate failure. The valgus angulation and the widened medial mortice were corrected in the ankles of both patients, who returned to full activities. The patients were followed to maturity; the correction has been maintained, and they remain asymptomatic. The technique used in these cases can correct valgus angulation secondary to loss of fibular congruity rather than only halting progression of the deformity.

Complex osteotomies vertebral column resection and decancellation

Pedicle subtraction osteotomy (PSO) is nowadays widely used to treat sagittal imbalance. Some complex malalignment cases cannot be treated by a PSO, whereas the imbalance is coronal or mixed or the sagittal imbalance is major and cannot be treated by a single PSO. The aim of this article was to review these complex situations--coronal imbalance, mixed imbalance, two-level PSO, vertebral column resection, and vertebral column decancellation, and to focus on their specificities. It wills also to evoke the utility of navigation in these complex cases.

Do we need to do overcorrection in Blount's disease?

PURPOSE

In order to prevent recurrent deformity, overcorrection in Blount's disease has been a common practice by most paediatric orthopaedic surgeons. However, some patients have persistent valgus alignment resulting in awkward deformity. The femoro-tibial angle (FTA) was measured in this series of cases to determine the necessity of such practice.

METHOD

During 1998-2010, patients with Blount's disease stage 2 by Langenskiold, aged from 30 to 40 months who had failed from bracing and underwent valgus osteotomy were included. Seventeen legs had postoperative FTA 7-13° (group 1) and 48 legs had postoperative FTA more than 13° (group 2). ROC curve was used to determine the appropriate FTA that was suitable to prevent recurrence.

RESULTS

Four legs had recurrence (28.6%) in group 1 and six legs (12.5%) had recurrence in group 2. Chi-square test between two groups were not statistically significant in recurrence (p = 0.434). Age and BMI were not statistically significant between recurrent and non-recurrent groups. The ROC curve shows that overcorrection more than 15° did not show benefit to prevent the recurrence in Blount's stage 2.

CONCLUSION

Our study showed that the overcorrection group had non-statistically significant recurrence compared to the non-overcorrection group, and overcorrection more than valgus 15° has no benefit to prevent recurrence.

Percutaneous femoral derotational osteotomy for excessive femoral torsion

Femoral derotational osteotomy is an acceptable treatment for excessive femoral torsion. The described procedure is a minimally invasive single-incision technique based on an intramedullary saw that enables an inside-out osteotomy, preserving the periosteum and biological activity in the local bone and soft tissue. After the osteotomy is complete and correction is achieved, an expandable intramedullary nail is used to achieve immediate stability, without the need for locking screws. Indications, tips, and pitfalls related to this novel osteotomy technique are discussed.

Total knee arthroplasty after high tibial osteotomy

High tibial osteotomy may be indicated in the treatment of varus knee in young, active patients. The preservation of proprioception and native joint and biomechanics is crucial for functional recovery in these patients. However, deterioration of initial good results can occur with time. In such cases, revision with total knee arthroplasty is indicated. However, this is a more surgically demanding option compared with a primary prosthesis. Accurate preoperative planning is mandatory to decrease the risk of intraoperative complications. A precise surgical technique, which is crucial to improving functional outcomes, includes hardware removal, joint exposition, tibial deformities due to previous osteotomy, and managing soft tissue mismatches. Possible technical challenges and surgical solutions exist for each of these aspects. However, several studies report lower functional results compared with primary implants. Thus, patients should be informed before high tibial osteotomy about its failure rate, the difficult surgical aspects of an additional prosthesis, and less satisfactory clinical results.

Bilateral double osteotomy in severe torsional malalignment syndrome: 16 years follow-up

Background

Torsional malalignment syndrome (TMS) is a well defined condition consisting of a combination of femoral antetorsion and tibial lateral torsion. The axis of knee motion is medially rotated. This may lead to patellofemoral malalignment with an increased Q angle and chondromalacia, patellar subluxation and dislocation. Conservative management is recommended in all but the most rare and severest cases. In these cases deformity correction requires osteotomies at two levels per limb.

Materials and methods

From 1987 to 2002 in our institution three patients underwent double femoral and tibial osteotomy for TMS bilateral correction (12 osteotomies). All patients were reviewed at mean follow-up of 16 years.

Results

At final follow-up no patients reported persistence of knee or hip pain. At clinical examination both lower limbs showed a normal axis and a normal patella anterior position. Pre-operative femoral version measurement showed an average hip internal rotation of 81.5° (range 80°–85°) and average hip external rotation of 27.2° (10°–40°). Thigh–foot angle measurement showed an average value of 38.6° (32°–45°). At final follow-up femoral version measurement showed an average hip internal rotation of 49° (range 45°–55°) and average hip internal rotation of 44.3° (20°–48°) (Figs. 1, 2, 3, 4, 5, 6). Thigh–foot angles measurement showed an average value of 21.6° (18°–24°) outward.

Conclusion

We recommend a clinical, radiographical and CT scan evaluation of all torsional deformity. In cases of significant deformity, internally rotating the tibia alone is not sufficient. Ipsilateral outward femoral and inward tibial osteotomies are our current recommendation for TMS, both performed at the same surgical setting.

Boomerang proximal tibial osteotomy for the treatment of severe varus gonarthrosis

PURPOSE

The purpose of the study was to review the results of modified infratubercle displacement osteotomy in patients with severe varus gonarthrosis and to determine the factors influencing outcomes.

METHODS

A total of 177 knees in 133 patients with severe varus gonarthrosis were treated with infratubercle boomerang-shaped osteotomy, stabilised with dual plates. The mean age of the patients was 63.8 years (range 43-80 years), and the mean follow-up period was 61.4 months (range 24 -139 months). The factors associated with clinical and survival outcomes were analysed including age, gender, body mass index (BMI), preoperative and post-operative femorotibial angle and femorotibial angle at one year after surgery.

RESULTS

Using the Knee Society clinical rating system 149 knees or 84.2 % were rated as having good to excellent results and 21 knees or 15.8 % as having fair to poor results. Overall, the mean preoperative knee score of 33.6 points had improved significantly to 80.7 points at the final follow-up (p < 0.001). Using Kaplan-Meier survivorship analysis the five-year survival was 97.1 % with conversion to arthroplasty or second osteotomy as the end point and 89.2 % with a knee score of under 70 points as the end point. The anatomical femorotibial angle at one year after osteotomy had the most significant positive effect on the clinical (p < 0.001) and survival outcomes for all end points (p = 0.002 for conversion to arthroplasty or second osteotomy and p < 0.001 for knee score less than 70 points).

CONCLUSIONS

The boomerang osteotomy can create adequate valgus alignment in severe varus gonarthrosis. The one-year post-operative knee alignment of 11° valgus provided the most satisfactory results and that between six and 15° valgus the longest survival time.

The effect of tibial tuberosity realignment procedures on the patellofemoral pressure distribution

PURPOSE

The study was performed to characterize the influence of tibial tuberosity realignment on the pressure applied to cartilage on the patella in the intact condition and with lesions on the lateral and medial facets.

METHODS

Ten knees were loaded in vitro through the quadriceps (586 N) and hamstrings (200 N) at 40°, 60°, and 80° of flexion while measuring patellofemoral contact pressures with a pressure sensor. The tibial tuberosity was positioned 5 mm lateral of the normal position to represent lateral malalignment, 5 mm medial of the normal position to represent tuberosity medialization, and 10 mm anterior of the medial position to represent tuberosity anteromedialization. The knees were tested with intact cartilage, with a 12-mm-diameter lesion created within the lateral patellar cartilage, and with the lateral lesion repaired with silicone combined with a medial lesion. A repeated measures ANOVA and post hoc tests were used to identify significant (P < 0.05) differences in the maximum lateral and medial pressure between the tuberosity positions.

RESULTS

Tuberosity medialization and anteromedialization significantly decreased the maximum lateral pressure by approximately 15% at 60° and 80° for intact cartilage and cartilage with a lateral lesion. Tuberosity medialization significantly increased the maximum medial pressure for intact cartilage at 80°, but the maximum medial pressure did not exceed the maximum lateral pressure for any testing condition.

CONCLUSIONS

The results indicate that medializing the tibial tuberosity by 10 mm reduces the pressure applied to lateral patellar cartilage for intact cartilage and cartilage with lateral lesions, but does not overload medial cartilage.

Complications after plate fixation and elastic stable intramedullary nailing of dislocated midshaft clavicle fractures: a retrospective comparison

PURPOSE

The incidence of operative treatment of dislocated midshaft clavicle fractures (DMCF) is rising due to unsatisfactory results after non-operative treatment. Knowledge of complications is important for selection of the surgical technique and preoperative patient counselling. The aim of this study is to compare complications after plate fixation and elastic stable intramedullary nailing (ESIN) with a titanium elastic nail (TEN) for DMCF.

METHODS

A retrospective analysis of our surgical database was performed. From January 2005 to January 2010, 90 patients with DMCF were treated with plate fixation or ESIN. Complications were evaluated in both treatment groups and subsequently compared.

RESULTS

Seven implant failures occurred in six patients (14 %) of the plate group and one implant failure (2.1 %) was seen in the ESIN group (p = 0.051). Major revision surgery was performed in five cases in the plate group (11.6 %) and in one case (2.1 %) in the ESIN group (p = 0.100). Three refractures (7.0 %) were observed in the plate group after removal of the implant against none in the ESIN group (p = 0.105). Six minor revisions (13 %) were reported in the ESIN group and none were reported in the plate group (p = 0.027).

CONCLUSIONS

Compared to other studies we report higher rates of refracture (7.0 %), major revision surgery (11.6 %) and implant failure (14.0 %) after plate fixation. The frequency of implant failures differed almost significantly for patients treated with plate fixation compared to ESIN. Furthermore, a tendency towards refracture after implant removal and major revision surgery after plate fixation was observed.

Cadaveric results of an accelerometer based, extramedullary navigation system for the tibial resection in total knee arthroplasty

INTRODUCTION

In total knee arthroplasty, the accuracy and precision of the tibial resection must be improved. The purpose of this study was to determine the accuracy and time associated with the use of an accelerometer based, extramedullary surgical navigation system for performing the tibial resection.

MATERIALS AND METHODS

Four orthopedic surgeons performed a tibial resection utilizing the KneeAlign™ system, each on five separate, cadaveric tibiae. Each surgeon was assigned a preoperative "target" of varus/valgus alignment and posterior slope prior to each resection. The alignment of each resection was measured using both plain radiographs and computed tomography, along with the time required to use the device.

RESULTS

Regarding coronal alignment, the mean absolute difference between the preoperative "target" and tibial resection alignment was 0.77° ± 0.64° using plain radiograph, and 0.68° ± 0.46° using CT scan measurements. Regarding the posterior slope, the mean absolute difference between the preoperative "target" and the tibial resection was 1.06° ± 0.59° using plain radiograph, and 0.70° ± 0.47° using CT scan measurements. The time to use the KneeAlign™ for the fifth specimen was less than 300 s for all four orthopedic surgeons in this study.

DISCUSSION

This cadaveric study demonstrates that the KneeAlign™ system is able to accurately align the tibial resection in both the coronal and sagittal planes.