Reliability of lower limb frontal plane alignment measurements using plain radiographs and digitized images

This study evaluated the reliability of lower limb frontal plane alignment measures obtained from plain radiographs measured manually and digitized images measured using a custom computer software package (TheHTO Pro; Fowler Kennedy Sport Medicine Clinic, London, Ontario, Canada). Radiographic measurements used in the planning of high tibial osteotomy, including the mechanical axis angle and mechanical axis deviation, were measured on 42 hip-to-ankle radiographs on two separate occasions by two different raters (A.V.S., J.J.D.). Intraclass correlation coefficients (0.96-0.99) indicated excellent agreement between the manual and computer measurements, suggesting both methods can be used interchangeably. Although test-retest and inter-rater reliability tended to be slightly better when using TheHTO Pro, intraclass correlation coefficients were excellent for both methods (0.97-0.99). The standard errors of measurement were <1 degree for mechanical axis angle and <2 mm for mechanical axis deviation, regardless of method or rater. Based on the observed standard errors of measurement, conservative estimates for the error associated with an individual's mechanical axis angle at one point is approximately 1.5 degrees, and the minimal detectable change on reassessment is approximately 2 degrees. The error associated with an individual's mechanical axis deviation at one point is approximately 4 mm, and the minimal detectable change on reassessment is approximately 6 mm. These results suggest that manual and computer measurements of lower limb frontal plane alignment can be calculated with minimal measurement error. However, the small errors associated with both methods should be considered when making clinical decisions.

A correction of windswept deformity by fixator assisted nailing

We report two cases with windswept deformities of the lower extremities. All deformities were corrected by fixator-assisted intramedullary nailing. At the latest follow-up, the patients had normal alignment, without symptoms and no loss of correction.

[CT analysis of leg alignment after conventional vs. navigated knee prosthesis implantation. Initial results of a controlled, prospective and randomized study]

INTRODUCTION

Correct alignment of the leg is one of the significant factors for the outcome after TKA. Previous studies have shown that the use of a navigation system can improve the alignment. However, for the positioning of the femoral component no validated data are available. This article presents the first results of a controlled, prospective and randomised trial comparing navigation versus free-hand implantation in TKA with special reference to the rotation of the femoral component.

METHODS

Since January 2003, all patients with primary arthrosis of the knee admitted to our hospital for TKA have been followed prospectively. For this first analysis, data were collected over a period of 5 months. Apart from the usual clinical evaluations, all patients had CT of the leg prior to the operation and 1 week postoperatively. Measurement of axis and rotation was performed by staff members of the X-ray department who had no knowledge of the operation technique (navigation vs. free-hand).

RESULTS

Twenty five sets of CT scans have been analysed, from 12 navigated operations and 13 freehand procedures. All 12 of the navigated knees were within the interval of +/-3 degrees varus/valgus deviation, but only 8 of the 13 non-navigated knees met this criteria. The analysis of the rotation position of the femoral component revealed no difference between the two groups.

CONCLUSION

By using an intraoperative navigation system, the accuracy of the alignment in TKA can be improved. Long-term studies will have to be carried out to verify whether this will lead to a lasting benefit for the patient. Concerning the rotation position of the femoral implant, no conclusion can be made regarding the recommended rotation position at this point of the study.

[CT-based and CT-free navigation in knee prosthesis implantation. Results of a prospective study]

INTRODUCTION

Accurate leg alignment is one important factor for long-term survival in total knee arthroplasty (TKA). The classical surgeon-controlled technique is associated with a deviation of the leg axis of more than 3 degrees in up to 30% of cases, regardless of the surgeon's experience. The aim of this study was to test the efficiency of a CT-based and CT-free navigation system in restoration of the leg axis.

METHOD

100 TKA (PFC-Sigma, DePuy) were implanted either using the CT-based or CT-free module of the Vector-Vision navigation System (BrainLAB). There were no significant differences between the groups in preoperative leg deformity. Accuracy of implantation was determined on postoperative long-leg coronal and lateral X-rays.

RESULTS

A postoperative leg axis between 3 degrees varus and 3 degrees valgus was obtained in 46 patients (92%) in the CT-based group (A) and in 48 patients (96%) in the CT-free group (B). No significant differences were found for varus / valgus orientation (+/-3 degrees ) of the femoral (A=96%; B=94%) and tibial (A and B each 98%) components.

CONCLUSION

The use of the CT-based and CT-free Vector-Vision system allows a significant improvement in the accuracy of implantation in TKA. The CT-based module has the advantage of precise preoperative planning. On the other hand there are additional costs and time-consuming logistics. The advantages of the CT-free module are the intraoperative visualisation of the leg axis, the ligament balancing and joint kinematics. Cutting errors can be detected and corrected with both modules.

[Stability, bone healing and loss of correction after valgus realignment of the tibial head. A roentgen stereometry analysis]

In high tibial closing-wedge osteotomies (HTO), closure of an osteotomy gap after resection of a bony wedge can be associated with a fissure of the medial cortex of the tibial head (MCT). The effect of a broken MCT on the recurrence of varus deformity is disputed. In this study, serial roentgen stereometric analysis (RSA) was used to determine the fixation stability of a rigid internal "L" plate after HTO. Full weight lower limb radiographs were used to determine the sagittal alignment in patients with varying degrees of varus malalignment and correction over time. Forty-two patients with varus gonarthrosis stage I-III (Ahlback) were treated with HTO and internal fixation with an L-shaped rigid plate. Patients were followed by serial RSA, conventional radiographs, and clinical evaluation (Hospital of Special Surgery score) over a 12-month period. In 19 of 42 successive patients, an average wedge size of 6.9 degrees was resected leaving the MCT intact (group 1). In 23 of 42 of patients, the MCT was unintentionally fissured during surgery when an average 10.3 degrees -wedge was resected (group 2). In group 2, RSA revealed a fivefold increase in lateral displacement of the distal tibial segment within 3 weeks after HTO. Twelve weeks after HTO, translations between tibial segments were below the accuracy of the RSA setup in the majority of patients. Group 1 patients demonstrated a higher initial fixation stability, less occurrence of varus deformity, and a higher HSS score compared to patients with larger wedge sizes and frequent fracture of the MCT (group 2). Before bone healing is achieved, the integrity of the MCT plays a crucial role for the clinical and radiological outcome after HTO.

[Possibilities of computer-assisted navitation in knee para-articular osteotomies]

Osteotomies in the knee region for incipient osteoarthritis in active patients have become increasingly popular in recent years. A computer-guided navigation system should help increase the surgeon's accuracy and lower the risk of intraoperative complications for this technically demanding type of surgery. Furthermore, computer navigation might be a powerful research and educational tool. The technical principles and the clinical implications of this system for knee osteotomies are described in the following article.

[Imaging and preoperative planning of osteotomy of tibial head osteotomy]

Valgus-producing osteotomy of the proximal tibia is a well-established treatment for medial femorotibial osteoarthritis in the varus knee. The ideal patient is active, under 55 years of age, has a stable varus deformity of less than 10 degrees, a good bone stock, and an osteoarthritis stage that is restricted to the medial compartment of the knee. Coventry reported a failure rate in proximal tibial osteotomy to be significantly higher when the postoperative alignment was less than 8 degrees of anatomical valgus. Hernigou noted better clinical long-term results in cases with a precise correction of malalignment. There are different preoperative planning methods varying between simple estimates of correction angles and specific radiographic planning tools. The reproducibility of operative outcome with regard to a predictable anatomic alignment and functional recovery must have high priority. This chapter deals with different preoperative planning methods to improve the reliability of surgical results after tibial osteotomy.

[Corrective osteotomy in primary varus, double varus and triple varus knee instability with cruciate ligament replacement]

Osteochondral lesions and osteoarthritis in young patients are often caused by chronic knee instability in varus malaligned knees. We present the indication, operative technique, and results of 57 patients treated by simultaneous high tibial osteotomy and cruciate ligament reconstruction. The indication for simultaneous high tibial valgus osteotomy and ACL reconstruction is chronic anterior knee instability in varus knees of patients under 40 years of age. In these patients, medial meniscus deficiency secondary to prior injuries and/or chronic knee instability have frequently led to unicompartmental (medial) tibiofemoral degenerative changes. The average correction angle of the osteotomy was 7 degrees (4-10). Subjectively, all patients reported an improvement of preoperative swelling, pain, and instability. Additional cartilage surgery or meniscus implantation did not significantly alter the clinical score values. Complications occurred in four patients. Unstable varus malangulated knees can be sufficiently treated by osteotomy and cruciate ligament plasty and is suggested as cost-effective therapy with good short-term results. Performing both operations in one procedure facilitates early rehabilitation and return of the patients back to the activities of daily living and sports.

[Closing wedge osteotomy of the tibial head in treatment of single compartment arthrosis]

Closing wedge high tibial osteotomy is an efficient method for the treatment of medial osteoarthritis of the knee. Prerequisites of successful surgery are proper indication and planning as well as the understanding of biomechanics and pathophysiology. The technique of osteotomy to choose (opening or closing wedge) depends on the type of malalignment and on additional pathologies. The surgical technique demands high precision to realize the planned correction and to avoid complications. Implants with angular stability provide advantages compared to traditional implants. Correct indication and surgical technique results in a desirable follow-up, which often lasts for at least 10 years. The effect on the prognosis of the young patient with cartilage damage is still unclear.

Minimally invasive unicompartmental knee replacement with a nonimage-based navigation system

In a prospective study, two groups of 20 unicompartmental knee replacements (UKR) each were operated either using a CT-free navigation system or the conventional minimal invasive technique. Radiographic assessment of postoperative alignment was performed by long-leg coronal and lateral radiographs. The results revealed a significant difference between the two groups in favor of navigation. In the computer-assisted group, 95% of UKRs were in a range of 4-0 degrees varus (mechanical axis) compared with 70% in the conventional group. The only inconvenience was a prolonged operation time (+19 min). Due to the limited exposure, the navigation system is helpful in achieving a more precise component orientation. The danger of overcorrection is diminished by real-time information about the leg axis at each step during the operation.

Impact of changing foot progression angle on foot pressure measurement in children with neuromuscular diseases

To analyze the effect of lower-limb rotation on foot pressure distribution, 16 patients (23 feet) with neuromuscular diseases who received derotation osteotomy of lower limbs without concomitant foot-ankle procedures were included in this retrospective study. The cross-correlation analysis showed that the interval change of the foot progression angle was correlated with the interval change of the medial-lateral foot pressure impulse distribution. The externally rotated foot progression angle tends to introduce higher loading on the medial foot, and the internally rotated foot progression angle shifts the loading to lateral side of the foot. This study provides evidence that the rotational profile of the lower limb has a substantial impact on foot pressure distribution.

Loss of alignment after surgical treatment of posterior Monteggia fractures: salvage with dorsal contoured plating

PURPOSE

To review the results of internal fixation with a dorsal contoured plate in patients with malalignment after internal fixation of a posterior Monteggia fracture.

METHODS

Seventeen patients with malalignment after surgical treatment of a posterior Monteggia fracture were treated with realignment of the ulna and fixation with a contoured dorsal plate. Fifteen patients had loose fixation and 12 patients had subluxation or dislocation of the ulnohumeral joint. Sixteen patients had fracture of the radial head and 9 patients had fracture of the coronoid process. Nine patients had ancillary procedures on the radial head, 4 had ancillary procedures on the coronoid, 5 had hinged external fixation, and one had fascial arthroplasty. Seven patients had another surgery before the final evaluation related to a complication in 6 patients and a to subsequent injury in 1 patient.

RESULTS

At the final evaluation at an average of 59 months the fracture was healed and the ulnohumeral joint was reduced concentrically in all 17 patients. The average arc of elbow flexion was 108 degrees and the average arc of forearm rotation was 134 degrees. The average American Shoulder and Elbow Surgeons Elbow Evaluation Score was 88. According to the system of Broberg and Morrey, the final result was rated excellent for 5 patients, good for 9, fair for 2, and poor for 1. One patient had fascial arthroplasty as part of the index procedure and 9 patients had radiographic signs of ulnohumeral arthrosis.

CONCLUSIONS

Malalignment after surgical treatment of posterior Monteggia fractures often is associated with unstable fixation. Dorsal contoured plating of the ulna in combination with other procedures can help salvage a malaligned posterior Monteggia fracture with satisfactory function restored in the majority of patients.

Calculation and correction of secondary translation deformities and secondary length deformities

External fixation correction of angular deformities leads to secondary translation deformities when occurring around an axis located proximal or distal to the center of rotation of angulation (CORA); secondary length deformities result when correction occurs around an axis concave or convex to the CORA. With circular fixation, the hinge axis can be matched to the CORA. With monolateral fixation, the level of the hinge/angulator is not easily controlled. Axis of correction of angulation can be plotted graphically and secondary deformities calculated trigonometrically. Location of the hinge/angulator can be accurately planned and adjustments incorporated to compensate for expected secondary deformities.

Treatment of nonunited hindfoot fusions

The management of delayed union and nonunion is complex and is contingent on appropriate diagnosis and classification. Detection techniques and treatment options, including cast immobilization, electrical stimulation, surgical repair, or a combination of regimens, are discussed in this article.

Korrektureingriffe am kindlichen Ober- und Unterarm

The causes of post-traumatic deformities of the upper and lower arm shafts as well as the complete elbow are 90% iatrogenic, in the area of the proximal humerus and the distal lower arm they are about 90% the result of chance (premature closure of the growth plate). In general, corrections of deformities are possible at any age, dependent on the patient's symptoms, the expected development, the location of the deformity and its changes during development. The correction technique should allow for the removal of all of the components of the deformity, and to retain the results until healing is complete and the patient's motor stability is ensured. Due to the high percentage of iatrogenic deformities, the optimisation of the primary therapy should receive particular attention rather than increasing the indications for a correction.

Repair of malunions after ankle arthrodesis

Ankle arthrodesis is an operation that produces fusion of the talocrural joint. Ideally, the ankle is fused in a position of slight valgus, neutral dorsiflexion, midsagittal translation, slight posterior translation, symmetric external rotation, and plantigrade foot alignment. Malunion after ankle arthrodesis is characterized as a deviation from this ideal position. The derangement may produce inefficient or painful gait and pain or dysfunction at the hip, knee, or foot. Preoperative planning is essential to achieve a final plantigrade foot position. Correction is accomplished through the ankle arthrodesis itself, the foot, or the supramalleolar tibia. Complications of ankle malunion repair include nonunion; malunion; nerve, vessel or tendon injury; and infection.

Revision of malaligned triple arthrodesis: a case report

Malalignment of a triple arthrodesis can pose significant challenges to the foot and ankle surgeon. Lack of a plantigrade foot will not be well tolerated by the patient and will often require revision of the original surgery. This article presents a review of the treatment algorithm used to address this unique problem. A case study based on this approach is also presented.

Deformity correction planning for hindfoot, ankle, and lower limb

Many patients with foot and ankle deformities have concurrent deformities (osseous and soft tissue), with or without limb length discrepancies. Lower extremity deformities and limb length discrepancies typically result from trauma, congenital abnormality, avascular necrosis, previous surgery, nonunion, and malunion. Limb deformity correction requires extensive surgical experience because many considerations and factors apply to realignment. The considerations and factors regarding realignment are highlighted throughout this article.

Chondral resurfacing and high tibial osteotomy in the varus knee

BACKGROUND

Treatment of patients with degenerative knees and varus malalignment presents a difficult clinical problem.

HYPOTHESIS

Combining a medial opening wedge high tibial osteotomy with the microfracture chondral resurfacing procedure is a viable treatment option.

STUDY DESIGN

Retrospective review of prospectively collected data.

METHODS

A group of 38 consecutive patients (mean age, 51.3 years; range, 34 to 72 years; 29 men and 10 women) with varus malalignment and chondral lesions who were treated with chondral resurfacing (an abrasion and microfracture technique) combined with a medial opening wedge high tibial osteotomy. All patients had >5 degrees of varus malalignment. Patients were evaluated preoperatively with the Lysholm and Western Ontario & McMasters Universities Osteoarthritis Index scoring systems and at a minimum of 2 years follow-up.

RESULTS

Thirty-three of 38 patients (87%) were available for 2-year follow-up (average, 45 months; range, 24 to 80 months). Lysholm scores improved from a preoperative score of 43.5 to 78.0 at follow-up; Western Ontario & McMasters Universities Osteoarthritis Index scores improved from 45.8 to 16.2. The average Tegner score was 5.0.

CONCLUSIONS

Combining a medial opening wedge high tibial osteotomy with the microfracture chondral resurfacing procedure in the varus knee is an effective method of decreasing pain and increasing function at a minimum of 2 years follow-up.

The accuracy of image-guided knee replacement based on computed tomography

Our study evaluated the accuracy of an image-guided total knee replacement system based on CT with regard to preparation of the femoral and tibial bone using nine limbs from five cadavers. The accuracy was assessed by direct measurement using an extramedullary alignment rod without radiographs.

The mean angular errors of the femur and tibia, which represent angular gaps from the real mechanical axis in the coronal plane, were 0.3° and 1.1°, respectively. The CT-based system, provided almost perfect alignment of the femoral component with less than 1° of error and excellent alignment with less than 3° of error for the tibial component. Our results suggest that standardisation of knee replacement by the use of this system will lead to improved long-term survival of total knee arthroplasty.

Computer-assisted knee arthroplasty versus a conventional jig-based technique

We have compared a new technique of computer-assisted knee arthroplasty with the current conventional jig-based technique in 70 patients randomly allocated to receive either of the methods. Post-operative CT was performed according to the Perth CT Knee Arthroplasty protocol and pre- and post-operative Maquet views of the limb were taken. Intra-operative and peri-operative morbidity data were collected and blood loss measured.

Post-operative CT showed a significant improvement in the alignment of the components using computer-assisted surgery in regard to femoral varus/valgus (p = 0.032), femoral rotation (p = 0.001), tibial varus/valgus (p = 0.047) tibial posterior slope (p = 0.0001), tibial rotation (p = 0.011) and femorotibial mismatch (p = 0.037). Standing alignment was also improved (p = 0.004) and blood loss was less (p = 0.0001). Computer-assisted surgery took longer with a mean increase of 13 minutes (p = 0.0001).

Die kniegelenknahe Focal-dome-Osteotomie

Focal dome osteotomy (FDO) is a cylindrically shaped osteotomy, with corresponding bone cuts rotating around the central axis of the deformity. Thus, complete correction can be achieved without secondary translation. FDO provides high adjustability of the bone ends, optimal bone contact, and high primary stability. As with straight cut closing, neutral, and opening-wedge osteotomies, FDO allows closing, neutral, and opening corrections. Opening FDO allows preservation of bone contact, whereas closing FDO does not require removal of bone stock. The osteotomy can be modified to tighten the medial collateral ligament. A FDO below the tuberosity does not compromise patellofemoral function and reduces the risk of intra-articular fractures. Sufficient bone stock of the proximal tibial or distal femoral fragment allows intramedullary stabilization. FDO is of high value in the treatment of sagittal plane and frontal plane corrections of the knee even in severe deformities.

Inkomplette, suprakondyl�re Femurosteotomie

The aim of treatment of a valgus deformity and osteoarthrosis of the lateral compartment of the knee is to obtain axial correction of the misalignment of the extremity. Osteosynthesis of the osteotomized femur using internal fixation and a stiff implant has not been as successful as expected. We evaluated the accuracy of correction and the stability of fixation with a malleable plate after supracondylar osteotomy of the distal aspect of the femur that was performed to correct a valgus deformity of the knee. We performed an incomplete oblique closing-wedge osteotomy of the distal aspect of the femur in 32 consecutive patients (34 knees) and stabilized the osteotomy site with a malleable, semitubular plate, which was bent to form an angled plate, and lag screws. Postoperatively, the patients were immediately encouraged to walk, with partial weight bearing on the affected extremity. The mean age of the patients was 52 years, and the mean follow-up period was 4.4 years. In 32 knees, the osteosynthesis withstood the mechanical loading that occurred during the functional rehabilitation program. Due to pain or incorrect weight bearing, splinting was necessary to maintain the integrity of the osteosynthesis in three knees. The osteosynthesis failed in two knees. The mean deviation of the achieved tibiofemoral axis in the healed bone from the intended tibiofemoral axis was less than 2 degrees, and the maximal deviation less than 5 degrees. The Insall score was 21 points higher 4.4 years postoperatively than it had been preoperatively. Our method allows reliable correction of the tibiofemoral axis using intrinsic stability mechanisms to compress the congruently aligned cut ends of the cortical tubes. We believe that our technique provides an alternative to osteosynthesis using of a stiff implant such as a fixed-angle blade-plate device.

Tibiakopfumstellung mittels Fixateur externe

External fixation is a proved method for high tibial osteotomies. It is easy to access, allows postoperative corrections of the alignment, and can be removed without additional narcosis. Disadvantages are the frequent infection of the pin tracks and discomfort in bearing compared to internal fixation. In our own study no difference between unilateral and bilateral fixation could be found regarding loss of correction and complications. The advantage of unilateral fixation is the possibility of doing an open-wedge procedure by unilateral continuous callus distraction (hemicallotasis). This is indicated if medial collateral instability can be compensated by the open-wedge technique. The occurrence of neural injuries was significantly less frequent after hemicallotasis. Regular radiological and clinical control of the axis is necessary to prevent loss of correction, which was significantly more frequent in open-wedge osteotomies.