[Abstract] Objective To investigate the clinical efficacy of the modified Ilizarov knee inversion external fixation orthosis combined with minimally invasive osteotomy technique for the correction of knee inversion deformity. Methods Retrospective analysis of 31 patients with internal derangement of the knee, 8 males and 23 females, aged 18-69 years, average (35.6±15.8) years, admitted from February 2002 to May 2010; 6 cases unilateral and 25 cases bilateral, total 56 knees. The preoperative internal knee rotation angle ranged from 1.7° to 38.2°, with a mean of 17.0°±8.8°; the American Knee Society Score (KSS) was 34-100 points, with a mean of (86.2±18.5). The position of the center of angular rotation and osteotomy orthosis was determined, and the tibia was osteotomized with a minimally invasive osteotome at the intersection of the tibial deformity, and the fibula was osteotomized under the head. The preoperatively assembled modified Ilizarov external fixator was fixed through pins, and the valgus deformity was progressively corrected by adjusting the length of the telescopic medial and lateral brace screws. The clinical orthopedic efficacy was evaluated using four items, including X-ray examination and KSS clinical score of the knee joint, combined with self-perception during walking and the presence of complications. Results All patients wore the Ilizarov external fixator in the lower extremity for 9 to 20 weeks, with a mean of 12 weeks. Patients were followed up on an outpatient basis for 14 to 50.4 months, with a mean of 30.5 months. At the last follow-up, the internal knee valgus angle ranged from -3° to 2.4°, with a mean of 1.7°±0.9°; the KSS score of the knee ranged from 75 to 100, with a mean of (96.1±7.7); the difference was statistically significant when compared with the preoperative one. The clinical efficacy of the knee KSS was evaluated: 49 cases were excellent, 6 cases were good, and 1 case was acceptable, with an excellent rate of 98.2% (55/56). 11 cases had mild needle tract infection in the early postoperative period, and the infection was controlled after routine dressing change; 3 cases had loose needle tracts after surgery, and the fixation strength was restored after needle tract replacement. Conclusion The modified Ilizarov knee internal derangement external fixation orthosis combined with minimally invasive osteotomy for the correction of internal knee derangement is minimally invasive, safe, dynamic orthopedic and meets the aesthetic requirements, and the clinical results are satisfactory.
[Keywords] Internal knee varus, modified Ilizarov orthosis, minimally invasive osteotomy
The Modified Ilizarov Device Combined with Minimally Invasive Osteotomy In the Treatment of Genu Varum Deformity
QIN Sihe,ZHENG Xuejian,XIA Hetao,HAN Yilian,REN Longxi.Department of Orthopaedic Surgery,Beijing Chuiyangliu Hospital,Beijing 100022,China
[Abstract】Objective To explore the clinical therapeutic effect of modified Ilizarov device combined with minimally invasive osteotomy for treatment Methods The information of 31 patients with genu varum deformity who were treated during the period between February 2002 and May There were 8 males and 23 females in this group with an age range of 18 to 69 years (median age 35.6±15.8 years). 56 knees were involved in the 31 patients,( 6 cases in unilateral side,25 cases in bilateral sides).Preoperative angle of genu varum was 17.0±8.8°. According to the KSS (American Knee Society Score,KSS),preoperative score was about 34~100 point with average of 86.2±18.5.After determining the After determining the center of rotation angulation, osteotomy was performed in the site of tibial deformity and below the fibular head with minimally invasive device. Prepared modified Ilizarov device was assembled and fixed with k wire.Then genu varum deformity was progressively corrected by adjusting the length of Finally standing full length X ray of both lower limbs were taken in all patients to ensure a regular return of the mechanical axis and Evaluation of therapeutic effect included X-ray film ,KSS score, subjective sensation, and occurrence of complication . Results:Modified Ilizarov device were used in 56 knees for 9-20 weeks( median 12 weeks),31 patients were followed up for 14 – 50.4 months (average 12 weeks). The angle of genu varum deformity was 1.7±0.9°,KSS score of knee was 96.1±7.7.There were significantly There was no obvious scar at last follow-up in all patients’ skin. According to KSS score,the results were excellent 49 knees, good 6 knees, fair one knee with excellent rate of 98.2%.The complication included pin site The complication included pin site infection in 11 patients and pin loosening in 3 ones.They were cured with replacing pin site and routine dressing change ro get well.Conclusion: Modified Iilizarov device combined with minimally invasive osteotomy for the treatment of genu varum deformity can achieve satisfactory therapeutic effect. It has many characteristics such as minimal invasion, safety, dynamic correction, and satisfying aesthetics standard.
Key words】 Genu Varum , Modified Ilizarov Device Minimally Invasive Osteotomy
Internal knee valgus is a common knee deformity that can develop in childhood and progresses with age, growth and weight-bearing walking [1]. As the line of gravity (mechanical axis) of the lower extremity is shifted medially to the center of the knee joint, the knee joint surface is unevenly stressed, resulting in abnormal appearance and gait of the lower extremity. For middle-aged and elderly patients with internal knee valgus can be treated with artificial joint replacement [3-4], while for young or compound lower limb deformity patients, they are mostly treated with osteotomy orthopedic and fixation surgery [5-7] Currently, Ilizarov external fixation brace for internal knee valgus is a commonly used orthopedic device, but we found in clinical application that Ilizarov device must be threaded with full pins and fine steel pins must be tensioned However, we found in our clinical application that the Ilizarov device must be threaded with full pins, thin steel pins must be tensioned, and pins can only be threaded at the distal tibia (above the ankle), and the external fixation brace basically spans the full length of the lower leg. This configuration and fixation method is suitable for heavy weight patients, while the national body size is smaller than the Russian nation, so this orthopedic brace is not fully applicable. In view of this, we changed the configuration and pin fixation method of the original external knee brace and designed a new external fixation brace for the correction of knee inversion deformity in the Chinese population. This study hypothesized that the new external fixation orthosis would be suitable for the correction of knee inversion deformity in the Chinese population and would achieve better clinical results.
Introduction of the device
The new external fixation orthosis for internal knee valgus (Figure 1). The proximal tibia consists of 1 C-shaped ring and 1 full ring, and the distal end consists of 1 full ring, and the 2 sets of rings are connected together by 4 extension rods with universal joints in the middle, forming a three-dimensional spatial orthosis that can change the fixation stiffness and flexibility. Depending on the type and degree of deformity of the knee joint, different attachments can be fitted to the basic external fixator to meet the orthopaedic needs. If the tibial inversion with shortening deformity, the heel part should be increased by a half ring, which consists of 3 dynamic joints plus springs connected with the ankle upper ring, forming a dynamic set of devices that can ensure the relative flexible movement of the ankle joint and avoid the formation of horseshoe foot.
Information and methods
I. General data
From February 2002 to May 2010, a new external fixation orthosis combined with minimally invasive osteotomy of the tubular bone (Figure 2, 3) was used to treat 31 patients (56 knees) with internal derangement of the knee, 8 men and 23 women; age 18-69 years, mean (35.6±15.8) years; 6 cases unilateral and 25 cases bilateral. Case characteristics: 9 cases were over 50 years of age and had osteoarthritis combined with internal derangement of the knee; 1 case was 18 years of age and had internal derangement of the knee caused by osteogenesis imperfecta; 21 cases were 20-45 years of age and had internal derangement of the knee caused by adolescent rickets, 5 of which also had internal rotation of the tibia. The preoperative valgus angle ranged from 1.7° to 38.2°, with a mean of 17.0°±8.8°; the American Knee Society Score (KSS) ranged from 34 to 100, with a mean of (86.2±18.5).
II. Preoperative examination and orthopedic surgery decision procedure
The lower limbs were routinely observed in different positions during standing, walking gait and joint function, and full-length standing orthopantomographs of both lower limbs including hip, knee and ankle, as well as lateral radiographs of the knee joint were taken. The full-length mechanical axis of the lower limbs and the anatomical axis of the tibia were analyzed, and the angle of inversion of the knee was recorded to determine the center of rotation of angulation (CORA) of the knee inversion deformity [9], and the osteotomy orthopedic position should be at the CORA (Figure 4,5). The center of the femoral head, the center of the knee joint, and the center of the ankle joint were marked on the X-ray film, and the axes of the femur and tibia were drawn by connecting the three centers, and the lateral angles of the two axes were measured as the femoral-tibial angle (FTA),FTA-180° as the inversion angle (α) of each knee joint (Figure 5). Preoperatively, the deformity was analyzed and discussed, lines were drawn on the radiographs to determine the deformity site and tabulated on the body surface, and orthopedic results were simulated on the computer if necessary. Finally, according to the size of the limb circumference, the corresponding diameter of the external fixation steel ring is selected (the ring is 3-5 cm from the skin).
Surgical method
Continuous epidural anesthesia, the patient is placed in the supine position, and a balloon tourniquet is installed on the upper thigh. The deformity and the osteotomy site were identified according to the preoperative X-ray drawing and tabulated on the body surface. The skin, subcutaneous tissue and fascia were incised in turn to expose and protect the common peroneal nerve, then the periosteum of the peroneal neck was incised and peeled off, the fibula was cut with a bone knife and the incision was sutured; if there was no compound deformity in the affected limb, the bone could be osteotomized in the middle and lower 1/3 of the fibula. In this group, 9 mild internal derangement of the knee were osteotomized at the middle and lower 1/3 of the fibula, and the rest were osteotomized under the head of the fibula.
The tibia was osteotomized with a minimally invasive osteotome at the deformity (CORA plane) without fracture after electric drilling bone perforation (Figure 3), and after the external fixation brace was installed, the residual bone cortex was osteotomized with a narrow bone cutter, and the separation of the osteotomized end was judged by rotating the fixed steel ring of the upper and lower segments of the osteotomy. The external fixation brace should be adjusted to a position consistent with the deformity of the limb, with the center of rotation of the joint at the same level as the deformity. Two sets of 2.5 mm full pins are crossed on the distal and proximal rings of the osteotomy site without tension fixation, and 1-2 5 mm threaded half pins are added medially to the proximal end of the osteotomy. Three to four 4-5 mm threaded half-pins are placed on the medial side of the distal tibia of the osteotomy, and the half-pins can be angled to increase the stiffness of fixation and avoid the need for full pins. The stiffness of the fixation depends on the patient’s weight and must be strong for early fixation. If the osteotomy end is close to the tibial plateau and the patient has laxity of the lateral knee ligament, two threaded nails can be worn in the distal femur to fix the affected limb across the knee joint when walking under weight after surgery, and to support the medial knee gap and reduce the extrusion of the medial knee cartilage when bearing weight after surgery. After the external fixation installation, the knee and ankle joints were passively flexed and extended to check whether the pins penetrated the tendons and whether the skin tension was appropriate, and if necessary, they were appropriately loosened.
IV. Postoperative treatment
If the alignment is good, the threaded rod of the external fixator can be rotated and adjusted to gradually correct the inversion deformity of the knee (Figure 6,7), and the patient is encouraged to start walking with a walker. The principle of adjustment is: the medial threaded rod is propped open and the lateral threaded rod is compressed, combined with the observation of the shape of the affected limb and the standing and walking function, regular radiographs are taken, and when the adjustment is expected to be completed, full-length radiographs in the weight-bearing position are taken to confirm the correction of the inversion deformity and the recovery of the mechanical axis of the lower limb. The threaded rod is added to lock the external fixation to avoid deformation of the affected limb during the exercise and walking process. The incision and the needle tract were changed 7 d after surgery, and gauze was wrapped between several needle tracts to prevent the needle tract from sliding between the needle tract and the skin interface, which can effectively reduce the leakage of the needle tract.
After the operation, according to the X-ray film, after the mineralization of bone scab is more satisfactory, the external fixation bracket pins can be partially removed to reduce the fixation stiffness, reduce the stress shading during the shaping of the amputated end, and the affected limb is properly walked with full weight for 4~6 weeks before the X-ray examination, if the strength of functional bone healing is met, the external fixator is removed. If the strength of functional bone healing is met, all external fixators will be removed.
V. Clinical efficacy evaluation criteria
The clinical orthopaedic efficacy was evaluated according to the preoperative and postoperative weight-bearing knee inversion angles (α) and the KSS clinical score of the knee [8], combined with the self-perception evaluation during walking and the presence of complications.
The KSS clinical score of the knee joint was evaluated in four aspects, including complaints of pain during level walking and stair climbing, joint stability, joint range of motion, and the degree of defects, with a score of 100 out of 100, with 85-100 being excellent, 70-84 being good, 60-69 being acceptable, and <60 being poor.
The self-perception evaluation of patients during walking included: very satisfied with the correction of deformity and complete relief of symptoms; satisfied with the correction of deformity and reduction of symptoms; average correction of deformity and no improvement of symptoms; unsatisfied with the correction of deformity and aggravation of symptoms.
VI. Statistical analysis
The SPSS 13.0 (SPSS Inc., USA) software was used to measure and record the knee inversion angle and KSS score, respectively, and the preoperative and postoperative measurement data were analyzed by paired data t-test. The test level a value was taken as one-sided 0.05, and the difference was considered statistically significant at P<0.05.
Results
All patients were followed up on an outpatient basis for 14 to 50.4 months, with a mean of 30.5 months, because they returned to our hospital for removal of the external fixator after surgery. The patients wore the Ilizarov external fixator for 9 to 20 weeks, with an average of 12 weeks. Compared with the preoperative period, all 56 lower limb internal knee deformities were corrected in 31 patients, knee morphology was restored, patients felt pain during walking, symptoms were reduced or completely relieved, and satisfactory results were achieved in self-perception evaluation of deformity correction.
At the time of the final follow-up, the internal knee valgus angle ranged from -3° to 2.4°, with a mean of 1.7°±0.9°, and the knee KSS score ranged from 75 to 100 points, with a mean of (96.1±7.7) points, both of which were statistically significant when compared with the preoperative period (p<0.01, Table 1). According to the KSS clinical scoring criteria of the knee joint, the group had 49 excellent knees, 6 good knees, and 1 acceptable knee, with an excellent rate of 98.2% (55/56). The patients had punctate pigmentation at the site of small skin incision, and none of them had obvious scar formation. One patient in this group with a KSS score of OK had a traumatic fracture after removal of external fixation, and the deformity healed after surgical fixation treatment, with increased inversion deformity and knee stiffness. Early mild postoperative pin tract infection occurred in 11 cases, and the infection was controlled after routine dressing changes; pin tract loosening occurred in 3 cases, and the pin tract was replaced without affecting the fixation strength. None of the cases in this group had complications such as non-union of the fracture and severe infection of the pin tract.
Table 1 Observed index changes of clinical efficacy of 56 lower limbs with internal derangement of the knee before and after surgery (n=56, )
Preoperative versus postoperation change of clinical observation index in 56 knees genu varum correction
Item
Knee inversion angle(α)
KSS score
Before surgery
17.0±8.8°
86.2±18.5
Final follow-up
1.7±0.9°
96.1±7.7
t-value
20.4
6.4
P-value
0.000
0.000
DISCUSSION
I. Advantages of the modified Ilizarov knee varus external fixation orthosis combined with minimally invasive osteotomy
(A) Minimally invasive osteotomy: The invention of controlled depth electric drill perforated osteotome has revolutionized the minimally invasive osteotomy method for tubular bone, since then, osteotomy no longer requires large skin incision, no peeling of periosteum and soft tissues, and avoids vascular and nerve collateral damage. Since the periosteum and extraperiosteal soft tissues are preserved, there will be no major displacement of the osteotomy end and no disruption of blood circulation, which facilitates bone healing at the osteotomy end. The skin incision is only 2 cm, and the skin incision is closed with 1~2 stitches at the end of surgery, which basically eliminates the skin incision scar and meets the aesthetic requirements of young women after lower limb orthopaedic surgery (Figure 8-10 typical cases).
(b) Cross-piercing of the distal tibia with full stitches was avoided. Only two 2,5mm steel needles were cross-pierced on the tibial tuberosity, and threaded half needles were threaded on the upper and lower segments of the remaining osteotomy, avoiding the needles from penetrating the muscles or tendons of the lower leg, reducing needle tract infection and facilitating the patient’s life such as wearing pants.
II. Design of osteotomy site and surgical technique
Take the vertex of the deformity as the osteotomy plane, so that the CORA and the osteotomy plane are at the same level. When the osteotomy plane is at the level of CORA and the osteotomy site is the axis of angular correction, there will be no displacement of the osteotomy ends after the completion of the orthosis; if the osteotomy plane is far from CORA but still takes CORA as the axis of angular correction, the mechanical axis will return to normal after the completion of the orthosis, but the ends need to be displaced from each other; if the osteotomy plane is far from CORA and takes the osteotomy end as the axis of angular correction, the orthosis will produce If the osteotomy plane is far from the CORA and the osteotomy end is the angular correction axis, the deformity will be secondary to the mechanical axis shift. The causes of the inversion deformity in this group of cases were congenital developmental malformations, sequelae of rickets, osteogenesis imperfecta, and 9 cases were over 50 years of age and were idiopathic with osteoarthritis of the knee joint. In order to obtain stable fixation of the proximal end of the osteotomy, the plane of osteotomy can only be located in the adjacent tibial tuberosity, and the osteotomy must be displaced while correcting the angular deformity in order to reconstruct the mechanical axis. Therefore, the center of rotation of the universal joint should be located on the CORA line (Figure 5B), which can avoid secondary axis deformation. The postoperative management and walking function training process should follow the basic principles of stress-stimulated osteogenesis by Ilizarov technique.
III. Problems
The relationship between the number of piercing pins, fixation stiffness and patient’s weight during surgery has not been grasped by reasonable standards, and the postoperative adjustment orthopedic process of the external fixator, the walking method of the affected limb exercise, the determination of bone healing strength, and the time of removing the external fixator are still not quantifiable and are mainly grasped by the comprehensive analysis of doctors’ experience. For the time of external fixator removal, the authors have the principle that it is better to remove it 3 weeks late than 1 day early. Whether the surgical orthosis of each patient can achieve satisfactory results also depends on the proficiency of the surgeon in this technology.
Fourth, surgical operation precautions
In this group of cases, the peroneal osteotomy is chosen to osteotomy in the inferior plane of the head.
In conclusion, the new external fixation orthosis combined with tubular bone minimally invasive osteotomy for the treatment of internal derangement of the knee is minimally invasive, safe, dynamic orthopedic and meets the aesthetic requirements [10], and the clinical results are satisfactory.
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