Multiplier method may be unreliable to predict the timing of temporary hemiepiphysiodesis for coronal angular deformity

Gradual Correction of Valgus Deformities of the Tibia Using a Monolateral External Fixator

Objective

To present a review of patients subjected to gradual correction of a valgus deformity of the tibia using a monolateral external fixator.

Method

This retrospective review included patients from January 2012 to May 2022 who met the following inclusion criteria: deviation of mechanical axis of the limb due to valgus deformity of the tibia; tibial deformity in the coronal plane on radiographic examination; a documented outpatient pre-operative evaluation by an orthopaedic surgeon and age between 10 and 70 years. The following exclusion criteria were applied: the presence of another tibia deformity preventing gradual correction using the proposed assembly; skin conditions incompatible with the surgical procedure; inadequate pre- or post-operative radiological evaluation; and insufficient information in the medical records.

Results

The mean age of patients with a valgus deformity of the tibia was 30.8 ± 15.9 years. These patients had a body mass index (BMI) of 26.1 ± 5.5 kg/m2. A congenital or developmental aetiology was attributed to 58.3% of the cases. Most commonly, the deformity was found in the middle third of the tibia with a mean deformity of 14.7 ± 6.6 degrees. The total external fixator time ranged from 73 to 229 days (average 149.7 ± 36.1 days). The mean medial proximal and lateral distal tibial angles differed significantly for pre- and post-operative measurements (p ≤ 0.05). There were complications in eight cases; five cases of pin site infections, two cases of medial cortical fracture and one case of peroneal nerve neuropraxia.

Conclusion

The proposed correction technique produces a satisfactory angular correction and with similar outcomes as described in the literature.

How to cite this article

Motta DP, Faria JLR, Couto A, et al. Gradual Correction of Valgus Deformities of the Tibia Using a Monolateral External Fixator. Strategies Trauma Limb Reconstr 2023;18(2):123-132.

Growth modulation for angular knee deformities: a practical guideline

PURPOSE OF REVIEW

This study aimed to review the established concepts and advances related to growth modulation for treating knee angular deformities. Although they are considered well tolerated procedures, careful indications and accurate techniques are necessary to ensure good results.

RECENT FINDINGS

In addition to general clinical and radiographic evaluations, new tools such as two-dimensional low-dose radiography and gait analysis have been used to clarify angular and torsional combinations and the impact of mild angulations on the knee joint. Temporary epiphysiodesis is commonly the choice, and it can be performed with different implants such as staples, tension band plates (TBP), percutaneous transphyseal screws (PETS), sutures, and screws.

SUMMARY

Considering its principles, TBP has been preferred for younger children. Cost can be a limitation, and research for alternative implants such as screws and nonabsorbable sutures indicate they might be an alternative in the future. In adolescents, PETS becomes an attractive alternative; however, its reversible character has been controversial, and further studies are needed to establish limits in younger patients.

Indications and timing in isolated medial femoral hemiepiphysiodesis for idiopathic genu valgum: A systematic review

INTRODUCTION

Temporary isolated medial femoral hemiepiphysiodesis (TIMFH) represents a safe and effective technique widely used to treat idiopathic genu valgum. Recent studies mainly concentrated on comparing outcomes of different implants, while less attention has been reserved to the proper indications and timing for surgery. The aim of this systematic review was to provide evidence-based guidelines about indications for device implant and removal and postoperative management.

METHODS

A comprehensive literature search was performed across three databases to select articles concerning TIMFH in the treatment of idiopathic genu valgum. Studies involving other etiologies or concomitant surgical procedures were excluded. Quality assessment of the included studies was conducted through the Newcastle-Ottawa Scale.

RESULTS

Ten studies involving 237 patients for a total of 446 knees were included in the analysis. Mean age at surgery was 11,4 years. Patients were considered for surgery using various clinical and radiological parameters. Intermalleolar distance (IMD) and mechanical lateral distal femoral angle (mLDFA) were the most common evaluated. Mean treatment time was 12 months. Rebound of the deformity occurred in 6,7% of cases.

CONCLUSION

Results of this review showed good consensus among authors. Patients undergoing TIMFH for IGV should be minimum 8 years old, with an IMD greater than 8 cm and a mLDFA lower than 87°. Postoperative management should comprise of quarterly clinic evaluations, and follow-up should last until skeletal maturity. The application of more uniform parameters in clinical practice may improve the establishment of the optimal timing for implant removal.

Coronal plane deformity around the knee in the skeletally immature population: A review of principles of evaluation and treatment

Coronal plane deformity around the knee, also known as genu varum or genu valgum, is a common finding in clinical practice for pediatricians and orthopedists. These deformities can be physiological or pathological. If untreated, pathological deformities can lead to abnormal joint loading and a consequent risk of premature osteoarthritis. The aim of this review is to provide a framework for the diagnosis and management of genu varum and genu valgum in skeletally immature patients.

Hemiepiphysiodesis for coronal angular knee deformities: tension-band plate versus percutaneous transphyseal screw

INTRODUCTION

Pediatric coronal plane knee deformities can be treated surgically using hemiepiphysiodesis. The two leading techniques used for hemiepiphysiodesis are: tension-band plates (TBP) and percutaneous transphyseal screws (PETS). We hypothesized that PETS would lead to faster guided correction of angular knee deformities than TBP.

MATERIALS AND METHODS

A retrospective cohort of 35 patients treated with either TBP or PETS in one medical institution was established. The cohort included both genu varum and genu valgum of both primary and secondary etiologies. We first compared the treatment groups for differences in demographic and malalignment characteristics. Then, we compared the treatment groups for differences in operation-related outcomes, radiological mechanical correction and complication rates.

RESULTS

We found that the use of PETS, compared to TBP, was associated with a faster implantation surgery and a shorter interval between implantation and removal, i.e., faster correction. Furthermore, PETS were associated with faster correction rates of the mechanical axis deviation, lateral distal femoral angle and medial proximal tibial angle. No significant differences in complication rates were found between the two treatments.

CONCLUSION

PETS provided a faster correction of angular knee deformities compared to TBP at similar complication rates. Hence, PETS could be considered a superior technique for hemiepiphysiodesis.

Risk factors for failure of temporary hemiepiphysiodesis in Blount disease: a systematic review

There is limited information regarding the use of temporary hemiepiphysiodesis for Blount disease. We performed a systematic review of patients treated for Blount disease using either extraperiosteal staples or plates to identify characteristics affecting clinical outcome, including the need for unplanned procedures. A total of 53 patients (63 bone segments) underwent temporary hemiepiphysiodesis at a mean age of 8.8 years (1.8-14.7 years). Overall, 32/63 (51%) segments achieved neutral mechanical axis and 31/63 (49%) underwent unplanned subsequent procedures, with or without a subsequent osteotomy. On the basis of the available heterogeneous data, neither age at index surgery nor the type of implant correlated with the need for unplanned additional surgeries.

How Accurate is the Multiplier Method in Predicting the Timing of Angular Correction After Hemiepiphysiodesis?

PURPOSE

The purpose of the study was to validate the accuracy of the Multiplier Method (MM) in predicting the timing of angular correction after hemiepiphysiodesis and to determine the role of using skeletal age when calculating those predictions.

METHODS

This retrospective study included 131 physes in 77 patients treated with hemiepiphysiodesis to gradually correct a coronal plane deformity before skeletal maturity. To compare the MM's predictions to the actual treatment duration, the "desired angular correction" was considered the actual achieved angular correction determined from the "endpoint x-ray" (last x-ray before implant removal). We measured the bone length and width of the growth plate from the preoperative x-ray and calculated the MM's prediction of the duration of treatment based on the MM formula. We compared the predicted duration to the observed duration of treatment for each case. The difference was calculated by subtracting the observed duration from the predicted duration. The result was the "absolute difference," which is the number of months over or under predicted by the MM.

RESULTS

The mean absolute difference between the MM's predicted duration and the observed duration was 2.31 months, which was highly significant (P≤0.001). The MM's prediction agreed with the observed duration of treatment (ie, zero absolute difference) in 15% of the predictions, 69% were under predicted, and 16% were over predicted. Sixty-eight percent of the absolute differences were within 3 months regardless of the direction of error. The mean difference was relatively less in genu varum cases and was statistically significant (P=0.047). Comparing the mean difference using chronological age and skeletal age in the formula showed no statistically significant difference.

CONCLUSIONS

The MM has a tendency to under predict. Therefore, doing a guided growth right before skeletal maturity should be started 2 to 4 months earlier than suggested by the MM. Moreover, our data did not show that the bone age gave more accurate predictions than chronological age.

LEVEL OF EVIDENCE

Level IV.