膝外翻矫正与双平面截骨术（2022）

膝外翻矫正与双平面截骨术（2022）Genu Valgum Correction and Biplanar Osteotomies

Taylor S, Getgood A. Genu Valgum Correction and Biplanar Osteotomies[J]. Clin Sports Med, 2022,41(1): 47-63.

转载文章的原链接1：

https://pubmed.ncbi.nlm.nih.gov/34782075/

转载文章的原链接2：

https://www.sciencedirect.com/science/article/abs/pii/S0278591921000776?via%3Dihub

Abstract

Valgus malalignment is an important risk factor in recurrent patella instability. This article explores the role of corrective osteotomy and discusses the various described methods both on the femoral and tibial sides of the joint. A detailed operative technique of medial closing wedge distal femoral osteotomy is included.

Keywords: Distal femoral osteotomy (DFO); High tibial osteotomy (HTO); Osteotomy; Patellofemoral instability; Valgus malalignment.

INTRODUCTION

Genu valgum is a potential contributor to patellofemoral instability.1–3 With increasing amounts of valgus angulation, the Q angle increases, resulting in a lateralizing force vector on the patella with respect to the trochlear groove.4 Correcting valgus angulation has multiple possible advantages. Importantly, neutralizing the valgus reduces this lateral force vector by effectively medializing the tibial tuberosity and thus decreases the risk of recurrent dislocation.5–7 It may also prevent the advancement or development of osteoarthritis in both the lateral tibiofemoral and patellofemoral compartment, although this has not been studied long-term in the patellar dislocation population.8–10 Last, it may also improve subjective sense of knee stability due to reduction of the abduction moment during stance phase.11 Despite the intuitive relationship between genu valgum and patella instability, evidence on the effectiveness of correction is limited to case series and reports,1,2,4,11 making definitive statements about its clinical utility challenging.

临床适用证CLINICAL INDICATIONS

Indications for correction of coronal plane valgus alignment include symptomatic patella instability. Definitions of patella instability vary in the literature; however, patients with recurrent dislocation, subluxations, and habitual dislocation have all been successfully treated with the procedure.4,9,12–14 Particular attention must be paid to the presence of untreated valgus in the setting of revision surgery; however, the threshold for intervention in the primary setting is unclear. A minimum threshold of mechanical tibiofemoral angle (mTFA) of 5°to 6° of valgus has been described with good results,15,16 although values as low as 2° also have been used.9 There are no studies that clearly define a degree of valgus, over which provides optimal outcome. As such, a careful examination of all bony and soft tissue factors contributing to the individual patient’s instability presents multiple opportunities for intervention. Identifying those at highest priority for intervention is challenging. Successful outcomes con be achieved through coronal plane correction alone14;however, most studies involve osteotomy in combination with at least one other procedure. Soft tissue procedures, such as medial reefing, lateral release,1,2,4,9,12,15,16 and medial patellofemoral ligament (MPFL) reconstruction,1 as well as bony procedures such as tibial tubercle osteotomy and derotational osteotomies4 have all been described. The presence of combined femoral anteversion and valgus may be treated together in a single supracondylar femoral osteotomy.17,18 Swarup and colleagues4 articulated “symptomatic” genu valgum, valgus in the presence of lateral knee pain, as the threshold for coronal plane correction. However, many patients with patella instability do not present with pain and thus other factors such as magnitude of valgus, ligamentous laxity, or absence of other correctable risk factors may be indications to proceed with osteotomy.12,13

Contraindications to coronal plane correction must also be considered. Certainly, medial compartment osteoarthritis is a contraindication for valgus correction but is fortunately rare in the patellofemoral instability population. Similarly, patellofemoral degenerative change has also been described as a contraindication15;however, both trochlear and patella-sided chondral injuries have been shown to improve following distal femoral osteotomy.9 As with most osteotomies, additional consideration must be given when offering surgery to patients with high body mass index and regular nicotine users.12

CLINICAL ASSESSMENT

Assessment involves that outlined in the article by Davis L Rogers and Andrew J. Cosgarea’s article, “Evaluating Patellofemoral Patients: Physical Examination, Radiographic Imaging, and Measurements,” elsewhere in this issue, with special attention to certain areas. The identification of valgus centers on visual inspection of standing coronal plane alignment and thus the clinician should have a low clinical threshold for obtaining radiographic assessment. The patient is assessed for both static and dynamic indicators of patella maltracking. The Q angle should be measured, with higher Q angles indicating an increased lateral subluxation vector on the patella.19

Care must be taken not to confuse a high Q angle with lateral patella tracking, as high Qangles are more commonly associated with medial rather than lateral patella placement.20 Regardless, patients with genu valgum will have increased Q angles and correction of the valgus medializes the tibial tubercle and will normalize the Q angle.18

The patient is carefully assessed for a J-sign in terminal extension/early flexion. Although the assessment is subjective, it clearly indicates excessive lateral patella translation in terminal extension.20 The severity of the J-sign can often be better appreciated when the leg moves from the extended to flexed position, as the patella may often “jump” back into the groove from its more lateralized position. The exact cause is not fully known, but may be a reflection of coronal or rotational deformities, patella alta, trochlear dysplasia, and muscle imbalance.21 Regardless of cause, the presence of a J-sign may indicate a more complex deformity and be associated with increased risk of isolated MPFL reconstruction failure.22

Identification of associated rotational deformities, increased femoral anteversion, and tibial torsion are made initially by assessing for squinting patella and in-toeing during gait and quantified further using hip range of motion and foot thigh angle in the prone position.

RADIOGRAPHIC ASSESSMENT

Long leg alignment films are taken. The mechanical axis of the limb is visualized by drawing a vertical line from the center of the femoral head to the center of the talus (Fig. 1).23 Valgus is noted if the line passes lateral to the tibial spines and can be quantified by measuring the mTFA (Normal=-1.0 ± 2.8°).24 The site of deformity is identified by measurement of the anatomic lateral distal femoral angle (aLDFA; Normal=81°± 2°)as well as the medial proximal tibial angle (mPTA; Normal=87°± 2°)noting that there may be deformity at more than 1 level (Fig. 2).20

Fig. 1. Standing long leg alignment film with mechanical tibiofemoral angle displayed

Fig. 2. Standing long leg alignment film. a:mTFA. β:aLDFA. θ:mPTA.

.

Careful attention should be paid to the positioning of the limb in the alignment radiograph. It is common to have these films taken with the patella pointing forward. In the patella instability population, the patella often sits more laterally. Thus, when the patellae are positioned forward, the femur may be internally rotated. This can result in the appearance of a valgus deformity, particularly if there are coexisting torsional abnormalities. A repeat alignment radiograph should be performed with the beam centered on getting an anteroposterior view of the knee. A clinical examination will help further determine whether torsional abnormalities coexist.

DECISION-MAKING ALGORITHM

See Fig. 3 for the decision-making algorithm:

Ø What is the site of pathology? Distal femur versus proximal tibia or both

Ø Does the size of correction warrant consideration of a double level osteotomy?

Ø How to correct? Opening versus closing osteotomy?

Fig. 3. Surgical decision-making algorithm

FEMUR VERSUS TIBIA

The site of deformity and size of correction are the 2 main factors traditionally considered in selecting the level of osteotomy. For congenital valgus, the deformity is most often encountered in the distal femur and is addressed at that site. For tibial-sided deformities, size of correction is important due to the joint line obliquity created during the osteotomy. Significant joint line obliquity may result in progressive lateral subluxation of the tibia.25 Therefore, patients with total valgus of 12° or post osteotomy proximal tibial joint line obliquity greater than 10° are likely better treated with femoral-sided osteotomy.6,26 In the osteoarthritis literature, secondary consideration is given to the fact that tibial-sided osteotomy maintains correction throughout the range of motion.27 Femoral osteotomy only corrects alignment in extension because at 90° of flexion the femoral weight-bearing surface moves to the posterior condyles: the position of which has not been changed by the coronal plane osteotomy.28 The clinical relevance of this in patellofemoral instability has not yet been established.22

Double-sided osteotomy can be considered when deformity at both the distal femur and proximal tibial is present7,29 or in patients with significant valgus (mTFA ＞10°).30 This allows for correction of both the joint line obliquity and coronal deformity.30–32

DISTAL FEMORAL MEDIAL CLOSING VERSUS LATERAL OPENING

In the following are considerations for the selection of opening versus closing wedge osteotomies of the femur (Table 1). In the osteoarthritis population, 2 systematic reviews described no difference in union or reoperation rates between the 2 techniques.33–35 However, small numbers and study heterogeneity prevented rigorous statistical comparison rendering the choice to be one of personal preference.26,27

Table 1 Considerations for the selection of opening versus closing wedge osteotomies of the femur

Schematic of the planning according to Dugdale and colleagues.41

BIPLANAR OSTEOTOMIES IN CORONAL PLANE CORRECTION

There are many possible advantages for consideration of performing a biplanar osteotomy or biplanar “cuts.” Biplanar osteotomies increase both axial stability of the osteotomy and increase the cancellous surface area for bone healing.18,36–38 On the femoral side, the addition of an anterior cut in the coronal plane also allows for more distal positioning of the axial portion of the osteotomy, avoiding violation of the trochlea.7 Furthermore, removal of a wedge of bone from the coronal plane osteotomy also allows for correction of axial/rotational deformities to be built into the osteotomy.7,18,37,38 Biplanar correction can alternately be achieved by performing a single oblique osteotomy.39

CLINICAL OUTCOMES

Rigorous and long-term outcomes for valgus correction in the setting of patella instability is lacking in the literature. A recent systematic review by Tan and colleagues40 analyzing femoral-sided corrections, included only 5 articles totaling 73 patients,4,9,12–14 with significant heterogeneity preventing data pooling. Nevertheless, both radiologic and clinical outcomes reported at a mean of 4 years postoperatively are promising. All included studies demonstrated a radiologic improvement in joint alignment, measured either by mTFA or mLDFA. Postoperative instability was present in only 2 of the 73 patients. Interestingly, both patients came from an article studying the role of osteotomy alone, which highlights the possible benefits of concomitant soft tissue reconstruction in reducing this complication further. One patient had a subluxation event without effusion and declined further intervention, and the second underwent tibial tubercle osteotomy at 3 years post valgus correction.14 Patient-reported outcome measures data vary widely; however, all studies reported an improvement in Kujala score. A clinically significant improvement in visual analog scale was noted in 3 studies.4,9,13

PREOPERATIVE PLANNING

The osteotomy is planned according to the method described by Dugdale and colleagues41 (Fig. 4).

This method can be applied to both femoral and tibial osteotomies. Care should be taken not to overcorrect, particularly on the femoral side, as the correction angle is measured at the joint line but the correction is made more proximally at the metadiaphyseal junction.

Ø Planning of lateral opening wedge high tibial osteotomy

l Typically done according to Dugdale and colleagues41 (see Fig. 4).

l aLDFA should be normal.

l Resultant correction will not create a joint line obliquity greater than 10°.

Ø Planning of medial closing wedge distal femoral osteotomy (MCWDFO)

l Typically done according to Dugdale and colleagues41 (see Fig. 4).

l Desired weight-bearing line between center of knee to tip of medial tibial spine.

l No overcorrection to varus to avoid overload.

Fig. 4. Calculation of osteotomy size. The planned mechanical axis is placed in the center of the tibia joint line from medial to lateral. Two lines are then drawn through this point. The first (line A, white)from the center of the femoral head and the second (line B, red) from the head of the talus. Ensure to extend these lines past the planned mechanical axis point. The intersection of these lines forms the angle of correction. To convert the angle of correction into millimeters of correction, the proposed osteotomy is drawn (line C, green), and the length of the line measured. From the planned mechanical axis point measure along line a, the distance of the proposed osteotomy. The distance from this point to line b is the millimeters of correction (line D, blue).23,28 (Data from Puddu G, Cipolla M, Cerullo G, Franco V, Giannı?,EG. Osteotomies: The Surgical Treatment of the Valgus Knee.; 2007., Chambat P, Selmi TAS, Dejour D, Denoyers J. Varus tibial osteotomy. Operative Techniques in Sports Medicine. 2000;8(1):44-47. doi:https://doi.org/10.1016/S1060-1872(00)80024-6)

PREPARATION AND POSITIONING

Ø Supine position on radiolucent/carbon table

Ø Lateral post lateral to the proximal thigh as well as footrest to enable a position of 30° flexion

Ø Tourniquet around proximal thigh (300 mm Hg)

Ø C-arm/fluoroscopy with sterile draping for intraoperative controls，Position on the opposite side of the patient to the osteotomy site

Ø Single-shot antibiotics following individual protocol for bone surgery

Ø Tranexamic acid 1 g intravenous at induction

SURGICAL TECHNIQUE

The most commonly performed varus producing osteotomy in our practice is a medial closing wedge distal femoral osteotomy. This provides a very stable construct for early

weight bearing and range of motion, with less likelihood for the need for hardware

removal. The approach is on the medial side allowing for an easy approach to perform-

ing a concomitant MPFL reconstruction. Furthermore, in cases of recurrent lateral patella dislocation (LPD) in which the lateral retinacular structures are tight, a lateral

opening wedge distal femoral osteotomy will cause and increase in lateral soft tissue

tension, which can paradoxically make the LPD worse. It is common that an extensive

lateral retinacular lengthening is required in these cases, and an MCWDFO does not compromise this soft tissue release.

MCWDFO

Ø Medial skin incision

Ø The Epimysium over vastus medialis is incised and the muscle elevated off the medial intermuscular septum. The septum is then released off the periosteum. A cob elevator is used to elevate the posterior periosteum away from the posterior femoral cortex along the path of the planned osteotomy. A blunt Hohmann retractor is then placed on the anterior and posterior femoral cortices (Fig. 5).

Fig. 5. Hohmann retractors in place over the anterior and posterior femoral cortices.

Ø Guide pins are then inserted at the proximal and distal boundaries of the osteotomy distanced at the medial cortex by the planned correction distance (Fig. 6). Their trajectory is checked with fluoroscopy. The length of the proximal and distal osteotomies is checked. Equal length will prevent a medial cortical，step when the osteotomy is closed and impart stability to compression through cortical apposition.37

Fig. 6. Guide pin insertion using a ruler to ensure appropriate pin distance on medial cortex.

Ø Mark the planned corticotomies with diathermy (Fig. 7). Biplanar femoral osteotomy is performed with an oscillating saw starting with the distal osteotomy, then moving forward to the proximal osteotomy, completing both with an osteotome to avoid lateral cortical breach. An additional coronal plane osteotomy is completed anteriorly providing rotational stability (Fig. 8), increased surfaced area for union, and more straightforward removal of the wedge. The resultant wedge of bone is removed (Fig. 9). A punch can remove any residual posterior bone.

Fig. 7. Marking of the planned anterior, proximal, and distal corticotomies with diathermy. Inset: radiographic medial corticotomy plan.

Fig. 8. Completion of the anterior or coronal plane osteotomy.

Fig. 9. Removal of the bone wedge.

Ø The osteotomy is closed gently and gradually to avoid hinge fractures. A controlled osteoclasis of the lateral hinge may be performed to weaken the cortical bridge without fracturing, using a 2.4-mm pin. The submuscular DFO locking plate is then positioned anteromedially on the distal femur. This ensures the plate is positioned parallel with the femoral shaft proximally and has good coverage by the medial vastus to reduce mechanical irritation.

Ø The plate is secured, and the closing wedge compressed in the standard fashion.

Ø Final fluoroscopic assessment confirms the desired coronal plane correction as well as correct screw placement (Fig. 10).

Fig. 10. Placement and securing of the locking plate. Inset: final radiographic appearance.

Less commonly, a tibial-sided correction is performed, either to address a primary tibial deformity or along with a distal femoral osteotomy to prevent creating an abnormal joint line obliquity. In these rare circumstances, either a lateral opening or amedial closing wedge technique may be used (Fig. 11).

Fig. 11. Example of a patient with double level osteotomies.

POSTOPERATIVE REGIMEN

Ø Touch weight bearing for the initial 2 weeks postoperatively then protected weight bearing until 6 weeks

Ø Hinged knee brace for 6 weeks (unlocked)

Ø Thrombosis prophylaxis with aspirin

Ø Immediate initiation of quads activation and knee range-of-motion exercises in brace

Ø Return to activity 12 weeks postoperatively (low impact) and 24 weeks postop-eratively (high impact)

COMPLICATIONS

Besides the general complication profile of bone surgery on the lower extremities, several complications specific to high tibial osteotomy and DFO have been reported in the literature (Table 2).20,23,26,27,

Table 2 Complications specific to high tibial osteotomy and distal femoral osteotomy

SUMMARY

Patients with patella instability require thorough clinical assessment to identify and quantify all possible bony and soft tissue contributing factors. Valgus alignment, where pronounced or in the setting of revision surgery, is corrected effectively via osteotomy at the site of deformity. For femoral-sided corrections, MCWDFO is preferred to the stability conferred by the osteotomy design. A low threshold is given to the addition of a soft tissue procedure, most commonly MPFL reconstruction.

CLINICS CARE POINT

Ø Particular attention must be paid to the presence of untreated valgus in the setting of revision surgery.

Ø Consider the need for combining corrective osteotomy with a soft tissue procedure where indicated.

Ø The presence of a J sign may indicate complex deformity and can be associated with increased risk of isolated MPFL reconstruction failure.

Ø Beware apparent valgus in long leg standing films. Ensure it has been taken with the femur positioned correctly and that there are not rotational deformities present.

Ø Be careful not to overcorrect. Correction planning occurs at the joint level but the osteotomy is performed in the metaphysis.

Ø Amedial closing wedge DFO provides a stable osteotomy for early weight bearing with a lower rate of hardware removal.