3.15 Proximal tibia
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1 Introduction
In the light of the increasing number of older adults with osteoporosis, treatment of proximal tibial fractures (PTFs) deserves new consideration. The increasing incidence, change in fracture types, new operative fixation techniques, perioperative risk, personal needs of the patient, and the general health conditions of the fragility fracture patient all demand a new way of thinking and approach for this type of injury.
Typically, geriatric PTFs present as lateral depression fractures caused by low-energy valgus stress in women. High-energy trauma in older patients presents as complex injury of the joint surface, the metaphysis, and the soft tissues. Preexisting muscle and skin atrophy often aggravate the situation. In this chapter, we discuss a new perspective on PTFs in the geriatric patient and present the available options. Poor bone quality should not be a limiting factor.
The proximal tibia is essential for weight bearing: 60% of body weight is transferred through the larger medial tibial condyle. The mechanical axis (Mikulicz line) of the leg crosses the knee joint approximately 2 mm medial to the intercondylar eminence. The anatomical axis of the knee joint has 5–6° valgus. In the older adult with preexisting varus or valgus axis deviations, altered forces are generated to the proximal tibial joint surface and may increase the risk of fracture [1]. Direct trauma to the knee joint is most commonly delivered to the lateral side, leading to a higher incidence of lateral proximal tibia fractures [2]. However, PTFs most commonly occur due to axial compression, in extension at the ventral rim of the plateau, and in flexion because of the roll-back of the femur at the dorsal rim [3]. Dorsal rim fractures are highly associated with knee dislocation and should be treated as unstable fractures.
2 Epidemiology and etiology
Kannus et al [4] investigated the incidence of osteoporotic knee fractures in a population of 100,000 people older than 59 years. They noted a dramatic increase of fractures from 1970 (218 per 100,000 women) until 1999 (685 per 100,000 women). Future predictions for 2020 and 2030 predict increases to 1,550 per 100,000 people (ie, women 1,250, men 300) and 2050 per 100,000 people (ie, women 1,700, men 350). Proximal tibial fractures have a bimodal fracture distribution, with increased incidence in older patients [5]. While they comprise 1% of all fractures in the overall population, they are responsible for up to 8% in adults older than 65 years [6]. From 2000 to 2007, the average age of patients with PTF increased from 48.9 to 56.0 years [7]. Both prevention and treatment of osteoporotic PTFs is an increasing priority.
3 Diagnostics
3.1 Clinical evaluation
Common reasons for a fall from standing height in older adults are frailty, sarcopenia, gait instability, and preexisting joint disorders. Sarcopenia has an incidence of 5–10% in people older than 65 and is a major cause for functional decline leading to falls and fractures [8]. Patients living in nursing homes with neurological comorbidities such as stroke or dementia often reach the hospital with some delay due to an inability to report the injury. Insufficiency fractures of the proximal tibia are often diagnosed with some delay resulting in secondary displacement [9–11], often requiring additional diagnostics ( Case 1: Fig 3.15-1 ).
Comorbidities such as heart failure and venous insufficiency leading to soft-tissue edema are commonly encountered. Parchment skin due to long-term corticosteroid use is another common issue.
CASE 1
Patient
An 86-year-old patient suffered a low-energy fall at home.
Comorbidities
Congestive heart failure
Chronic kidney failure
A recent deep vein thrombosis due to immobility
Treatment and outcome
In the conventional x-rays, the trauma surgeon suspected an avulsion of the anterior cruciate ligament ( Fig 3.15-1a ). Computed tomographic scans showed the true extent of the fracture, which reached into the medial metaphysis ( Fig 3.15-1b ). Avoiding fracture displacement allowed for a percutaneous screw fixation. In order to gain a better screw purchase, the surgeon decided to augment the hollow metaphysis of the tibia with polymethylmethacrylate cement ( Fig 3.15-1c–d ).
Physical examination should follow this sequence:
Inspection of the soft tissue, particularly in cognitively impaired geriatric patients or polytraumatized unconscious patients where verbal history is limited. Deformation of the knee, bruises, and pressure marks can help to understand the trauma mechanism.
Peripheral neurovascular examination.
Evaluation for compartment syndrome. This can occur in geriatric trauma patients taking antithrombotic or anticoagulant medications. Some case reports describe compartment syndromes triggered by spontaneous drug-induced bleeding [12–14].
Examination of ligament stability and meniscal injuries:
The risk of ligament and meniscal injury is higher in high-energy trauma of young patients compared to geriatric patients where the osteoporotic bone has a higher risk of fracture [1, 15]. Ligament injuries in the young (< 60 years), after high-energy trauma constitutes 49–54% [16, 17] versus 5% [6] in older adults.
Valgus stress leading to lateral depression fractures have a higher risk of medial collateral ligament rupture [17, 18].
The risk of lateral meniscal tear in lateral depression fractures increases eightfold with displacement > 10 mm [15].
Anterior or posterior cruciate ligament rupture or avulsion in older adults are signs of higher instability, which require further evaluation of the neurovascular structures in the popliteal cavity.
Swelling of the knee and evaluation of the soft-tissue envelope:
In case of a joint effusion, diagnostic and therapeutic knee puncture may be considered to relieve acute pain.
Soft-tissue edema and skin laceration may delay surgery.
3.2 Imaging
AP, lateral, oblique, and patella sunrise views of the knee joint are recommended. In case of unclear findings, further evaluation by means of computed tomographic (CT) scan or magnetic resonance imaging (MRI) should be added. Note that 6.3% of knee fractures are missed in emergency x-rays [19]:
For CT scans a slice thickness of 1 mm is recommended [20, 21].
Insufficiency fractures of the proximal tibia are often missed with plain x-rays and are best detected using MRI [9].
If surgery is indicated, CT scans are necessary for planning surgery. Most of the newer classification systems of the PTF are based on CT scan findings, which allow a better mapping of the fractured columns [20–22]:
Three-dimensional reconstructions of the fragments allow a better preoperative planning of the approach and choice of osteosynthesis.
Two-dimensional reconstructions of the fragments along the axis allow better estimation of fracture dislocation.
Concomitant soft-tissue injuries such as ligament avulsion or rupture can be best diagnosed using MRI [23, 24]. In case clinical examination of the knee stability is limited due to swelling, MRI imaging is strongly recommended preoperatively. The degree of ligament injury influences the timing of definitive surgery and the need for provisional stabilization [24].
3.3 Local bone quality
Cancellous and cortical bone decrease in the proximal tibia over time:
Chen et al [25] identified reduction in trabecular number and thickness by means of high-resolution peripheral quantitative CT, showing a decrease in bone mineral density (BMD) of 4% per decade from 57–96 years.
Cortical thickness of the tibia is typically smaller than at the proximal femur [25].
Cortical porosity decreases over time [25].
4 Classification
The most popular classification systems for PTFs are in descending order the Schatzker [26], AO/OTA [27], and Hohl and Moore [28] classifications. First attempts to classify PTFs were made by Schatzker as early as 1979, which categorized six fracture patterns based on AP x-rays. The AO/OTA classification was strongly related to Schatzker′s system but was part of a larger classification system for bone fractures, easier to remember and reproduce. The main difference between the two classifications is the addition of extraarticular fractures, type A. The Hohl and Moore classification is still often mentioned but has been outdated [29], perhaps due to its similarity to the Schatzker classification.
Characteristics of the Schatzker, AO/OTA, and Hohl and Moore classifications:
Fractures are categorized into depression, monocondylar, or bicondylar fractures.
All three systems are based on plain AP x-rays.
Schatzker has the best interobserver and intraobserver reliability [29].
The wide availability of CT and 3-D fracture images has added to classification schemes of PTFs. While the Schatzker and AO/OTA classifications focus on the two condyles in AP view, shearing fractures of the dorsal rim of the tibial plateau are missed. Luo et al [22] first introduced the three-column classification system ( Fig 3.15-2 ), which produces a more comprehensive evaluation with a high relevance for surgical decision making.
The three-column classification has the following advantages:
Three-dimensional mapping of the proximal tibia.
Better intraobserver reliability than Schatzker (0.810 versus 0.758) [20].
A more comprehensive evaluation of the dorsal column fracture, which has a high incidence of 28.8% [21].
Allows better surgical planning and operative positioning in the case of dorsal column involvement [22].
5 Decision making
5.1 Fracture dislocation or osteoporotic fracture?
It is essential to evaluate whether the knee is in stable or unstable condition.
In patients younger than 60 years, posteromedial rim fractures are highly associated with knee dislocation and ligamentous injuries. Tscherne and Lobenhoffer [30] found 96% of anterior cruciate ligament (ACL) injuries and 85% medial collateral ligament ruptures in this fracture type are unstable. In older adults the osteoporotic bone often fractures before ligament ruptures occur, but:
Large posteromedial rim fractures should always be treated as unstable.
Osteoporotic depression fractures at the posterolateral and central rim are not necessarily unstable.
Additional avulsion fracture of the ACL is a clear sign for knee dislocation and instability [31].
Unstable fractures are typically associated with substantial soft-tissue swelling and should be treated in two stages. An external fixator until the time point of open reduction and internal fixation (ORIF) is usually necessary.
5.2 Nonoperative versus operative treatment
In general, nondisplaced PTFs that are stable to varus and valgus stress can be treated nonoperatively. Ten degrees of varus axis deformity can be considered as unstable and requires operative treatment [32, 33]. Due to pain, clinical evaluation for ligamentous instability is difficult in acutely injured patients and can often result in further fracture displacement due to manipulation.
Minimally displaced depression fractures of the lateral proximal tibial plateau (zero-column, Schatzker III, AO/OTA 41B2.1), where the articular surface is maintained (depression ≤ 2 mm) and limb alignment is not disrupted, should be treated nonoperatively with a hinged brace or with a long leg cast in cognitively impaired or noncompliant patients [34–36]. However, one can question if the so-called critical size of 2 mm step-off for operative treatment is a relevant rule for older patients. Frail geriatric patients who are unable to tolerate surgery may require nonoperative treatment.
Segal et al [37] extended their indication of nonoperative treatment of lateral depression and split-depression fractures to 5 mm and had overall 95% of satisfactory results compared to operative treatment.
On the other hand, depression fractures tend to deteriorate in osteoporotic conditions because of bone voids. It might be reasonable to prevent varus or valgus deformation by prophylactic operative stabilization.
5.3 Operative approach
The operative approach can be based on the three-column classification.
5.3.1 Zero-column fracture (Schatzker type III)
Pure depression fractures in the lateral proximal tibial plateau without involvement of the cortex are classified as zero-column fractures ( Fig 3.15-3a–b ). The operative approach can be made from lateral or medial via a small cortical window to elevate the depression ( Fig 3.15-3c–d ) [38–40]. In case of additional fixation, plate or screw osteosynthesis is performed from a lateral approach ( Fig 3.15-3e–f ) [38]. In osteoporotic bone, indirect elevation of the articular surface may not be possible or may be destructive. Balloon tibioplasty with subsequent augmentation is an alternative ( Fig 3.15-3g–h ).
5.3.2 One- and two-column fracture (Schatzker types I and II)
Simple lateral split or split-depression fractures usually involve the lateral anterior and/or the lateral posterior column and can be classified as one- or two-column fractures. The fracture can be best reached via a lateral straight incision in supine position. Voids or defects after joint reconstruction can be addressed with cement, bone substitutes, or allogenic bone grafting.
5.3.3 Two-column fracture (Schatzker type IV)
Medial condylar fractures usually involve the anteromedial and posteromedial column and are classified as the typical two-column fractures. Based on the two-column principle, an operative approach is possible in most cases from posteromedial to buttress the dorsal fragment with a plate, placing the patient in supine or prone position. The anteromedial fragment can be reached by medial subperiosteal dissection of the medial tibial rim and can also be addressed with a buttress plate [22].
5.3.4 Three-column fracture (Schatzker types V and VI)
Bicondylar fractures are often combined with a posterolateral fragment and thus classified as a three-column fracture ( Fig 3.15-4a–c ). Understanding and recognition of the additional dorsal fragment changes the recommendation from a single anterior approach to a double anterolateral and posteromedial incision ( Fig 3.15-4d–g ) [41, 42].
Some authors still recommend the single anterior incision, which may be useful in case of later salvage arthroplasty [43, 44]. However, we recommend a double incision (anterolateral and posteromedial), which allows better reconstruction of the joint surface and is associated with a lower risk of wound infections in critical soft-tissue conditions, leading to good results ( Fig 3.15-4h–i ) [45–47].
6 Therapeutic options
6.1 Nonoperative treatment
The general recommendations for nonoperative treatment are:
Immobilization with an adjustable hinged knee brace [3].
Beginning with full extension during the first 2 weeks will help to decrease swelling, and starting early with range of motion (ROM) is essential to prevent contracture and muscle atrophy in frail geriatric patients [48, 49]. Continuous passive motion (CPM) may be used.
Concomitant ligament injuries will increase the risk of knee contracture [50]. Twenty degrees of flexion contracture significantly influences gait velocity and stride length [51] and may lead to further falls in older adults.
General recommendations are limited weight bearing for 6–8 weeks, although partial weight bearing may be impossible to achieve in older or cognitively impaired patients. Nonoperative treatment of lateral split and depression fractures in the young did not result in depressions greater than 2 mm [37]. No data are available for older cohorts.
6.2 External fixator and percutaneous reduction
The external fixator is the method of choice in cases of severe soft-tissue damage or vascular disease, which prevents primary ORIF surgery [52]. In older adults, soft-tissue edema and vascular disease can produce extensive swelling after low-energy trauma despite less severe fracture patterns (zero-, one-, or two-column, Schatzker types I–IV). In this situation using the external fixator may be considered. Fracture reduction can be performed percutaneously with minimal blood loss and without extensive soft-tissue exposure. Biomechanical studies support full weight bearing [53, 54]. No studies exist for osteoporotic bone.
6.3 Plate fixation with temporary external fixator
In comminuted bicondylar fractures of patients with poor bone stock, hybrid techniques of temporary external fixation to supplement the plate or screw fixation have been introduced as a promising new approach to allow immediate mobilization with weight bearing as tolerated ( Case 2: Fig 3.15-5 ) [52, 55].
Ali et al [56] prospectively investigated 11 patients with an AO/OTA 41C2 or 3 fracture treated percutaneously with intrafragmentary screw fixation, followed by neutralization with a stable external fixator and early mobilization:
Follow-up after 38 months
11 of 11 radiologically healed fractures
9 of 11 satisfactory results according to the Rasmussen score for postoperative knee function evaluation
2 of 11 revisions: one total knee arthroplasty (TKA), one corrective osteotomy
5 superficial pin-track infections, no deep infection
Krappinger et al [55] presented two cases of AO/OTA 41C3 fractures, which were initially stabilized with external fixation followed by additional internal fixation with anteromedial and anterolateral angular stable double plating after soft-tissue consolidation and external fixation for 8 weeks:
Follow-up after 12 months
2 of 2 pain-free results
ROM: 0–100°
No radiographic progression of the preexisting significant osteoarthritis and no loss of reduction
6.4 Lateral locking plate
6.4.1 Indication 1
Lateral locking plate fixation is also indicated for unicondylar, lateral or medial, PTFs (one- or two-column, Schatzker I, II, IV, AO/OTA 41B1, B3, C1) ( Case 3: Fig 3.15-6 ) [70–72].
Gösling et al [73] performed biomechanical studies in cadaver bones with medial condylar fractures (Schatzker type IV, AO/OTA 41C1) instrumented with a lateral angular stable plate to double plating with a lateral buttress plate and a medial antiglide plate:
No significant difference between the two techniques in regard to axial weight bearing.
Maximum loading was 1,600 Newton (N), which showed plastic vertical subsidence of 1.1 mm in the single plate group versus 1.5 mm in the double plate group:
1,600 N are approximately 163 kg which far exceeds a healthy body weight.
Limitation of the study was the missing data with respect to bone quality or age of the specimens.
Gerich et al [52] reported a retrospective cohort with mean age of 69 years that showed the following poor results: ten split-depression fractures, two split fractures, and three bicondylar fractures were treated with ORIF and lateral angular stable locking plate. Loss of reduction had occurred in 13 of 15 cases.
In osteoporotic bone, additional implant augmentation with PMMA might improve these results [74].
CASE 2
Patient
An 81-year-old woman sustained a comminuted bicondylar fracture of the left proximal tibial plateau ( Fig 3.15-5a–b ).
Treatment and outcome
Temporary transarticular stabilization with a bridging external fixator was performed because of soft-tissue swelling; it was left in place until the swelling was reduced and soft tissue consolidated ( Fig 3.15-5c–d ). Open reduction and internal fixation was preformed after 2.5 weeks with reconstruction of the joint congruency via a single midline incision, open reduction, and defect filling with a fresh frozen bone allograft. A lateral undercontoured buttress plate combined with a medial antiglide plate was applied ( Fig 3.15-5e–f ). Due to the poor bone stock, the surgeon decided to continue using the external fixator in addition to plate osteosynthesis. The patient was mobilized with partial weight bearing (30 kg). The external fixator was finally removed after 3 months and full weight bearing was allowed.
At the 1-year follow-up, osseous consolidation, full knee extension, and 100° of flexion were achieved ( Fig 3.15-5g ). The patient was able to walk with one stick and live on her own. At the 2-year followup, the patient presented again with increasing pain. The x-rays showed osteonecrosis of the lateral proximal tibia with increasing valgus ( Fig 3.15-5h ).
Discussion
A 2-staged procedure as proposed in this case is the gold standard for comminuted proximal tibial plateau fractures, with large soft-tissue damage after high-energy trauma [57, 58].
A midline approach was chosen in order to keep the external fixator in place and for better filling of the central defect with an allograft.
However, it should be remembered that the risk of poor healing due to soft-tissue stripping and fragment devascularization is higher using a midline approach [52, 59]. Newer studies have shown that the timing of the definitive osteosynthesis has a higher influence on soft-tissue healing than the choice of approach [60, 61]. Nevertheless, a midline approach is no longer recommended.
Allograft bone was chosen to prevent donor site morbidity [62, 63]. Osteonecrosis occurred with subsidence of the laterocentral joint surface after 2 years ( Fig 3.15-5g–h ). Polymethylmethacrylate (PMMA) shows better results with regard to prevention of loss of reduction over time [64].
Angular stable plate fixation has shown good results to prevent loss of reduction. However, in osteoporotic bone, osteosynthesis failure is described frequently [6, 52, 65]. These results led to the decision to additionally maintain the external fixator, because the degree of comminution did not allow PMMA implant augmentation without the risk of cement leakage into the joint.
In this case the patient was allowed to partially bear weight and was mobilized with the help of two crutches. The importance of early mobilization for geriatric patients has been described in several studies to prevent complications related to immobilization [66, 67]. The 1-year follow-up showed satisfactory results with respect to bone healing, soft-tissue healing, and range of motion ( Fig 3.15-5g ). Unfortunately, osteonecrosis occurred after a 2-year follow-up. The mechanical axis of the leg was still maintained, which is the most important goal for complicated proximal tibial fractures ( Fig 3.15-5h ) [3, 68, 69]. Secondary total knee arthroplasty can now be considered after bone healing and maintained axial alignment.
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